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HomeMy WebLinkAboutLocal Erosion Management Plan Nov 95 i t I I I I I I I I I ! I ! I I I i I TO WN OF SO UTHOLD Southold, New York Prepared for: Town of Southold Town Halt Southold, New York 1197l Prepared by: Allee King Rosen & Fleming, Inc. 117 East 29th Street New York, New York 10016-8022 (212) 696-0670 In association with: Moffatt & Nichol Baltimore, Maryland 20814 The Saratoga Associates Saratoga Springs, New York 12866 November 1995 SOUTHOLD EROSION MANAGEMENT PLAN November 1995 Prepared for: Prepared by: Town of Southold Allee King Rosen & Fleming, Inc. Moffatt & Nichol, Engineers The Saratoga Associates SOu'J:uO~O ~ROSION }~.GRNRI~ PL~L~ TA~.~- Off CONT]f.,.N~S ACKNO~rr.e-~C~Q~TS CHAP£--~ I. COASTAL PKOCESS ~ SHORELINE EVOLUTION A. COASTAL GEOMORPHOLOGY COASTAL PROCESSES Winds Waves Water Levels Astronomical Tides Storm Surges Sea Level Rise Currents Sediment Characteristics and Supply Storms Human Activity and Land Use Dredging Hardened Structures Soft Engineering Solutions Land Use Flood-Prone Areas C. SUMMARY ~11~F£~ II. A. B. REACH 1: C. REACH 2: D. REACH 3: E. REACH 4: F. REACH 5: G. REACH 6 H. REACH 7 I. REACH 8 INvEnTORY OF SOu'£UOLD BY RRA~ LONG ISLAND SOUND SIDE OF THE TOWN OF SOUTHOLD TOWN LINE TO DUCK POND POINT DUCK POND POINT TO HORTON POINT HORTON POINT TO ROCKY POINT ROCKY POINT TO ORIENT POINT ORIENT POINT TO YOUNGS POINT (GREENPORT] FANNING POINT TO FOUNDERS LANDING FOUNDERS LANDING TO INDIAN NECK INDIAN NECK TO DOWNS CREEK REACH 9 DOWNS CREEK TO THE TOWN LINE REACH 10: FISHERS ISLAND Number S-1 I-1 1-2 I-5 I-7 I-8 I-lO I-lO 1-11 I-t3 1-14 1-15 1-16 1-19 1-19 1-21 1-28 II-9 II-10 II-1 II-1 II-1 II-2 II-3 II-3 II-3 II-5 II-6 II-7 1-31 1-30 1-31 C~IAW'£~a III. A. B. COMMON NANACEI~NT UNITS INTRODUCTION LONG ISLAND SOUND COAST Jetty Areas Areas of Low Bluffs and Dunes Areas of High Bluffs PECONIC BAY SIDE OF SOUTHOLD Creek Mouths Exposed Shores Protected Shores Flood Prone Areas III-1 III-1 III-1 III-1 III-3 III-3 III-4 III-4 III-5 III-5 III-6 IV. PIIOPOSED E~LOSION ~(ANAC~U~T POLICIES A. PREAMBLE POLICY STANDARDS Policies Reflecting State Laws and for Setting Priorities In Erosion Control Structures Natural Protective Features Policy to Protect Public and Public Trust Lands Policy on Water-Dependent Uses Policy on Expenditure of Public Funds for Erosion Control Policy on Limiting Damage in the Coastal Area IV- 1 IV- 1 IV-3 IV-3 IV- 5 IV- 5 IV- 6 IV-6 IV-7 POST STOP~ P~COv~atY POLICIES POST STORM RECOVERY Introduction Post Storm Recovery Goals by Co.on Management Unit Long Island Sound Side Jetty Areas Low Bluffs and Dunes Areas of High Bluffs Peconic Bay Side Emergency Permits V-1 V-1 V-1 V-1 V-1 V-1 V-2 V-3 V-4 c~a~fl~ VI. I~PT.~TATION OPTIONS IMPLEMENTATION OPTIONS Studies Capital Projects Long-Term Coordination Government Agencies Private Foundations VI-1 VI-1 VI-1 VI-2 VI-2 VI-2 VI-3 ~SSARY G-1 APPENDIX A LONG ISLAND SOUND E~LOSION MaNAG~ POLICIES A-1 I I I I I I I i I I I ! I I I I I I I SOuT~OLD ~OSION NANAG~T PLAN LIST OF TABLES I-1 Long Island Extreme Wind Velocity Records I-2 Southold Area Fetch Distances I-3 Southold Tidal Ranges I-4 Historical Storms Affecting the New York Coast I-5 Summary of the Volumes of the Sand Removed from the Area West of Jetties of the Mattituck Inlet I-6 Summary of Town of Southold Dredging Projects PaRe N~mber I-8 1-10 1-11 1-18 1-20 1-22 ! I I I I I I I I I I I I i I I I I ~-TST O~ ~TgU~ES Chapter I I-1 Typical Bluff-Backed Beach Profile I-2 Typical Spit and Tombolo Formations I-3 Storm-Induced Profile Erosion Schematic I-4 Wave Height Estimates I-5 Wave Period Estimates I-6 · High Tide Frequency -- New London, Connecticut Chapter II II-1 Southold Reaches II-2 Geographic Names II-3 Deduced Direction of Littoral Drift II-4 Natural Shoreline Features II-5 Environmental Sensitivity II-6 Structural Shoreline Protection II-7 Land Use II-8 Mattituck Inlet 6~apter III III-1 Common Management Units Following Pa~e Number I-3 I-6 I-8 I-lO 1-10 1-12 II-1 II-1 II-1 II-1 II-1 II-1 II-1 II-1 III-1 ! I I I I I I I I I I i I I I I I I I ACKNOWLEDGldENTS This report is the synthesis of input and support from a large number of people. Ruth Oliva, Town Deputy Supervisor, has spent long hours chairing meetings with elected officials, agency personnel, and local citizens. Ruth has been the main force behind producing this report and has been very support- ive throughout the process. Town employees Valarie Scopaz, Town Planner, and Jim McMahon, Community Development Director, have provided valuable resources in developing the information base. They have collected information from nu- merous sources, scouted out reports and other data, and guided us on field trips. Steve Ridler, Fred Anders, and John Novak of New York State Department of State have provided technical guidance throughout our work and have provided many insights on statewide policy concerns. The Local Waterfront Advisory Committee has given their insight into local concerns. A number of Southold residents have given of their time and shared their knowledge with us. Many have submitted reports, photographs, and written re- cords of their observations and comments on the effects of coastal processes in Southold. Their help supplied the local knowledge that is vital to this type of analysis. They include Donald Stanton, Reach 2; Whitney Booth, Reaches 2 and 3 (Horton Point); David S. Corwin, Reach 3; Louis Emmanuele, Reach 4; William W. Wetmore, Jr., Reach 6 (Conkling Point); Judith Phiney, Reach 7 (Town and 3ockey Creeks); Ronnie Wacker, Reach 8 (Nassau Point)~ Joe MacKay, Reach 8; Joe Gold, Reach 8; Harry P. Taylor, Reach 9 (Deep Hole and Downs Creeks); and Norman Wamback, Rick Curcio, and Eugene Bozzo, Reach 9 (James Creek). We thank each of them for their help. i ! I ! I I I I I I I I I I I I I I I I EXECUTIVE SUI~.iAKY CAUSES OF EROSION The Long Island Sound Shoreline The primary cause of erosion on Southold's Long Island Sound side is lit- toral drift caused by wave action. When waves break on Southold's shore at an angle, the water moves in the direction of the wave angle, taking sand with it in a natural ongoing process called littoral drift. In Southold, the predomi- nate direction of littoral drift is eastward, but major storms -- which can generate waves higher than 6 feet -- often move the sand from east to west. Generally, the cycle of beach building and erosion takes place over long periods of low winds and waves action when the sand moves slowly west to east and builds up a gently sloping beach. During the large winter storms, the sand moves quickly from east to west and off-shore. These storms remove the sand and 19ave behind a stone and cobble beach. As long as the bluffs remain in a natural condition, the beaches heal themselves over the summer and Southold's shoreline erodes slowly over time. Points form around the areas with large rocks and cemented sands in the bluffs. Areas with low bluffs and clayey soils become embayments. Although Southold's Long Island Sound shoreline is eroding slowly, overall it is stable. However, jetties to keep inlets open and groins and bulkheads to keep the bluffs from eroding have, in places, taken the system out of equilibrium. Because of the bluffs, coastal flooding is localized along this shoreline. Very high tides rise to the toe of the bluff, but the houses are not flooded. In certain low-lying areas, such as the east side of Mattituck Inlet, localized flooding does occur. The Feconic Bays Shoreline The causes of erosion on Southold's Peconic Bays are more complex. Litto- ral drift dominates in areas exposed to waves. Going from west to east, the bays become smaller, and therefore the bay waves are smaller. The shoreline on either side of James Creek is fully exposed to waves from Great Peconic Bay, where the waves can reach a height of almost 5 feet. Robins Island affords S-1 some protection to Cutchogue Harbor and the west side of Nassau Point, but the east side of Nassau Point is exposed to Little Peconic and Hog Neck Bays. Southold Bay and its waves are smaller. At the far east end of Southold, Hal- lock Bay is almost totally enclosed. However, the Peconic shore, unlike the Long Island Sound side, has no high bluffs. Therefore, when a storm causes erosion, the shoreline quickly moves long distances landward. In addition, flooding is common along the shore. To protect these low flat shores, over the years property owners have built many groins to hold the beaches and bulkheads to raise the ground level. Currents are the second cause of erosion on the Peconic shores. Baymen report eddies in many of the bays, indicating that the water flows constantly in one direction, no matter whether the tide is flooding or ebbing. These offshore currents cause elongated features, such as Nassau Point. Compared with the two inlets on the Long Island Sound side of Southold, at least 25 inlets -- or more, depending on how they are counted -- are found on the Peconic side. The tidal currents flowing through these inlets move and deposit sand, both inside and outside of the inlet's mouth. Under natural con- ditions, an inlet tries to maintain a shallow channel and form shoals around its mouth. However, these inlets are dredged for boat navigation. These deep- er channels have changed the currents, which leads to different erosion pat- terns. The interaction of waves, offshore current eddies, tidal flows through inlets, and human construction leads to a series of complex erosion and deposi- tion systems that change seasonally and yearly in response to the weather. CONDITION OF SOUTHOLD'S SHOItELINES The Long Island Sound Shoreline This shoreline has two inlets, both protected by jetties -- Mattituck In- let and Goldsmith Inlet. Mattituck Inlet is heavily used by recreational and commercial boaters. It is a maritime center of statewide significance whose uses are an important aspect of Southold's character. The shoreline west of the inlet (updrift side) has generally come into equilibrium with the jetties, but the shoreline east of the jetties has not. It has eroded close to the jetties, and the low bluffs and dunes cannot supply sufficient sand to prevent the shoreline from eroding. Goldsmith Inlet is not navigable and is not used by boats. Dredging by the Town keeps it open; otherwise it would probably be $-2 I I I I I I I I I I I I I I i I I I I closed. Like Mattituck Inlet, the west side (updrift) has come into equili- brium while the east side has not. During the past five years, portions of the shoreline open to the north- east have been very heavily eroded by a series of storms, some of which had characteristics of the 100-year storm. Over a period of about the past 50 years, the same areas have eroded but at a much slower rate. The rate of ero- sion during the past five years seems to be anomalously high. The level of shore protection construction is also evidence of the long-term lower rate of erosion. Only a few thousand feet of bulkhead and less than 100 groins have been built over the approximately 25 miles of Southold's Long Island Sound shoreline. The long-term shoreline erosion is slow and the bluffs have been able to resupply the sand lost to the system. The Peconic Bays Shoreline The Peconic shores have been subjected to many erosion control structures to prevent rapid landward migration. Over its more than 35 miles of shoreline, more than a thousand groins have been built; where houses have been con- structed, about 50 percent of the shoreline is bulkheaded. Most of the more than 25 inlets are protected by jetties. In 27 separate areas, the Town has undertaken almost 150 dredging projects since the 1960's. Suffolk County dredges at least five creeks yearly since the 1950's. This heavy investment has maintained the shoreline, and few, if any, houses have been lost to ero- sion. However, several areas still flood regularly, leading to property dam- age. The high level of investment will continue to be necessary in the future to prevent loss of property and minimize damage. F. ECOI~ENDATIONS FOR ACTIONS The Long Island Sound Shoreline The Board of Trustees should closely examine each permit application to determine if the shore protection structure is necessary. Only those proper- ties that are in imminent danger should qualify for a permit. In addition, the proposed shore protection structure's potential effects on its neighbors during the next few years and the long term must be analyzed. Will the structure cause immediate erosion on the downdrift side? Will it reduce the supply of S-3 sand to the system and other properties over time? These kinds of questions must be answered before granting a permit. The same requirements should apply in a post-storm situation when a property owner applies to rebuild a structure. Several zoning mechanisms can be used to reduce potential damages to new buildings. For new lots, a shoreline setback should be instituted. Further study is needed to set the absolute number, and the setback distance could vary from reach to reach. Rates of erosion for specific areas must be determined. However, a 150-foot setback and a 50-foot natural vegetation buffer, both from the high water line or the toe of bluff, could be a reasonable starting point. These setbacks would require an assessment of lot sizes in several areas. The Peconic Bays Shoreline The shape of the shoreline is highly dependent on human activity, includ- ing dredging and a multitude of shore protection structures. Changes from this approach would lead to loss of property, and some of these losses could occur quickly. Therefore, the permit application do not need to present the more de- tailed analyses for permits required on the Long Island Sound side. However, in areas where structures do not dominate, such as Hallock Bay, they should be discouraged. The use of dredged materials is very important, although current practices do not recognize this. Nor are decisions about where and how the dredged mate- rials are used subject to rigorous review. The dredged materials should be used to build beaches, dunes, and other types of natural protective features. Currently, these materials are often just piled, and, in one observed case, used for filling in wetlands. Instead, this material should be placed on eroded beaches in a gentle slope like a beach. The three concerned government agencies -- the Board of Trustees, Suffolk County, and New York State Department of Environmental Conservation -- should meet regularly to jointly decide where and how the dredged material is placed. I~s decisions must be reviewed annually in light of the weather and level of e~osion over the past winter season. The decision must not be left to the dredge operator. S-4 I I I I I I I I I I I I I I I I I I I Townw[de Actions Southold should include shore protection structures in its building code. The type and size of the structure and the building materials used to construct it can be restricted by the building code. Existing groins vary widely in height, length, and spacing. Som~ are ef- fective in trapping enough sand to keep a beach full, while bypassing the rest to the downdrift beaches. However, some groins are so high and long that they trap all the sand, and bypass none to the downdrift side, effectively causing the beaches to erode. Others are totally ineffective, either because of design flaws or lack of maintenance. A Townwide building code could prevent new prob- lems and rectify some existing ones in post-storm situations. The building code should set the top elevation and the downward slope of the groin in order to retain sufficient sand to protect the property while not completely blocking the flow to downdrift properties. In addition, the length of individual groins and the spacing between them would be regulated. These are two interrelated factors. Development and enforcement of a shore protection building code would bring order and reason to the current variety of shoreline structures, some of which are in conflict with each another. Coastal processes can be confusing to people who are not used to living by the sea. Many newcomers (and some long-time residents) do not understand ero- sion and its causes. The meetings that the Town of Southold has been holding are an meaningful beginning to the process of educating the public, but they must be continued. Informative booklets and pamphlets -- such as those pub- lished by the East End Economic and Environmental Institute, Inc. -- are addit- ional important tools. The public must be made aware of the dangers of siting a house on the water's edge. I I I I I I I I I I I I I I I I I I I CHAPTER I. COASTAL PROCESSES AND SHORELINE EVOLUTION This chapter summarizes and is an introduction to coastal processes and their interaction with Southold~s shoreline. The intent of this chapter is to present an overview of the coastal processes affecting Southold. Chapter II contains the detailed, reach-by-reach description of Southold. As an introduc- tion to the physical processes governing the evolution of the coastal environ- ment and their complexity, the following is from the U.S. Army Corps of Engine- ers' Shore Pro~ec~ion Manual (1984): .... The beach and nearshore zone of a coast is the region where the forces of the sea react against the land. The physical system within this region is composed primarily of the motion of the sea, which supplies energy to the system, and the shore, which absorbs this energy. Because the shoreline is the intersection of the air, land, and water, the physical interactions which occur in this region are unique, very complex, and difficult to fully understand. As a consequence, a large part of the understanding of the beach and nearshore physical system is simply descriptive in nature. A general discussion describing the physical coast with emphasis on the Southold region is presented below. Included are the evolution of Long Island, the forces that act on the shore, and its reaction to these forces. The chap- ter is divided into three sections: 1) Coastal Geomorphology -- development of Long Island and existing coastal landforms; 2) Coastal Processes -- forces affecting shoreline change; and 3) Southold Coastal Conditions -- response to normal and storm-induced conditions along the project shoreline (e.g., flooding and beach and ~luff erosion). A glossary of pertinent coastal engineering and coastal geology-related terms is included for further reference. Primary ref- erences used throughout this document include: Governor's Coastal Erosion Task Force, Final Report, Volume II, LonE- Term SCrategy (GTFII 1994); I-1 Shore Protection Manual, U.S. Army Corps of Engineers (USACE 1984); North Shore of LonE Island, Suffolk County, New York, Beach Erosion Con,roi and Interim Hurricane S¢udy (Survey) (USACE 1969); and 0 Erosion of ¢he North Shore of LonE Island by Davies, Axelrod, and O'Connor (Davies et al., 1973). A. COASTAL GEOMOKPHOLOGY The marine coastline of the Town of Southold includes the shorelines along the northern shore of Long Island from the western Town boundary (Mattituck Hills) to Orient Point; the southern coastal areas fronting Gardiners Bay, Orient Harbor, Shelter Island Sound, Hog Neck Bay, the Peconics (Little Peconic and Great Peconic Bays), and Flanders Bay; and Fishers Island in Block Island Sound. Southold's shorefront features include beaches, bluffs, dunes, wet- lands, and barrier landforms. Topographic character and sediment composition of the area determine the manner in which these landforms interact with the marine environment, thus affecting coastal erosion and flooding. This section s,,mmarizes the development of the Long Island coastal complex, including the evolution of the shoreline and its landforms to the current configuration. To fully understand the physical environment and its dynamic character, its development must be examined historically. The following paragraphs, from GTFII (1994), discuss the area's geologic history. .... Glacial advance during the Pleistocene epoch generally ended at the approximate centerline of what is now Long Island (Fuller 1914). Seaward of the glaciers, extensive outwash plains of sand and gravel were deposited on top of pre-existing sediments and the gently seaward sloping At- lantic Coastal Plain. Glacial termination along an east- west front resulted in the present east-west orientation of the south shore. Outwash glaciation resulted in sand depo- sition on the adjacent continental shelf. .... gently seaward sloping rocks of the Atlantic Coastal Plain are buried beneath more recent semi-consolidated and I-2 unconsolidated sediment. Pleistocene sediment deposited over the last 2 million years was greatly modified during the last glacial episode. Surficial sediment of Long Is- land is composed of a variety of loosely consolidated gla- cial material deposited primarily as moraine or outwash. Further modification by rising seas over the past 15,000 years has resulted in the present geomorphic landforms. About 20,000 years ago, the final period of glaciation, known as the Wis- consian, glaciers stopped extending southward and started to retreat. This was not a smooth, one-way process, but involved several advances and retreats. Along Southold's Long Island Sound shore, a ridge of glacial materials -- com- prising clay, sand, cobbles, and boulders -- was deposited. This landform is called a recessional moraine, and the Harbor Hill recessional moraine forms the bluffs of the current shoreline. This recessional moraine contains highly variable sediments that cause the changes in beach character along Southold's Long Island Sound shoreline. Coastal areas are typically described both in profile and plan. A sche- matic beach profile is depicted in Figure I-1 (refer to the glossary for defi- nitions of specific terms). This profile is valid for almost all of the Long Island Sound side of Southold. On the Peconic Bay side, it is valid without the bluff for shoreline away from the creek mouths. Specific landforms common along the Southold coastal region include beaches, dunes, bluffs, spits, tom- bolos, inlets, and tidal and non-tidal wetlands. These landforms are defined in the glossary included at the end of this report section, and are summarized below. Beaches. Along the seashore and acted on by waves, tides, and cur- rents, the zone of unconsolidated material that extends landward from the low water line to the place where there is a marked change in material or ~hysiographic form, or to the line of permanent vegeta- tion. Figu{e I-1 depicts the interaction of the sea with a typical beach profile backed by bluffs. Beaches are found along the whole length of Southold's Long Island Sound shore. e Dunes. Ridges or mounds of loose, unconsolidated sand, that back the beach, providing added protection against wave attack and flooding I-3 6,95 _ ¢gq!tol area . Coast ! ~ Beach or lhorl Near,horo !on9 (deflool oreo of noorlhoro currentl) Back,hare _ ~re,~ Inshore or IhOrlfOCI ~ ~Off~hore ~ - ~ - ~ (extend, through breaker zone) ~ Surf Zonn Cre~t of berm ~- -- -- H~k ~r I~ Bottom Source: U.S. Army Corps of Engineers, Shore Protection Manual, 1984 Figure I- 1 Beach Profile and Definitions I I I I I I I I I I I I I I I I I I I during storm events. Dunes are found adjacent to Mattituck and Gold- smith inlets and at Horton Lane Beach. Bluffs. A high steep bank or cliff. Deposited during glacial move- ment, these coastal landforms are highly susceptible to erosion and collapse because of their steep seaward slope. Bluffs line much of Southold's Long Island Sound shore and the east side of Little Hog Neck. Spits. Formed when the dominant waves and currents carry sediment into an elongated subaerial depositional feature, extending away from a headland. Generally oriented parallel to the shoreline, with sedi- ments transported along the trunk of the spit to its end in deeper water, thus permitting the spit to grow longer. Spits grow in a variety of shapes depending on local bathymetry, sediment supply, tidal conditions, and wave climate. Spit growth often forms shore- line features, such as cuspate bars .and baymouth barriers. These are commonly found on the Peconic Bay side of Southold. Typical examples are the mouths of Town and Mill Creeks, as well as the elongation of Nassau Point. Inlets. A short narrow waterway connecting a bay, lagoon% or similar body of water with a large parent body of water. Inlets are highly dynamic with natural tendencies toward movement and closure, and subsequent openings of more efficient inlets. They are often stabi- lized for navigation requirements. The Peconic Bay shore of Southold has many inlets, while only Mattituck and Goldsmith Inlets exist on Southold's Long Island Sound shore. Tidal and non-tidal wetlands. Tidal and non-tidal wetlands are low- lying areas subject to frequent inundation by tidal flows or storm tides, or merely having a ~elatively high water content. These areas are established in locations with little wave energy, allowing vege- tation to establish itself away from destructive wave energy. Along Long Beach Bay, for instance, the protected shorelines have allowed the establishment of extensive wetland areas. I-4 I I I I I I I I I I I I I I I I I I I Shorelines fronting Long Island Sound are characterized by nearly continu- ous bluffs composed of loosely consolidated glacial outwash (primarily sand) and moraine material, which is a mix of clay, silt, cobble, and boulder. The glacials expanded from the north, carrying this mixture of sediments with it. When the climate warmed, the advance of the glacier slowed, then stopped with back-and-forth shudders. During this process, the morainal materials were de- posited in a long ridge shape along the face of the glacier. As the glacier retreated with the warming climate, sand was deposited in outwash plains. This stopping and retreating formed what later became Southold's bluffs, dunes, and beaches. Material eroded from the bluffs enter the littoral system, contribut- ing to beaches of varying width, slope, and sediment character. Beaches front- ing Southold consist of sediments ranging from sand to cobble, with widths ranging from 25 to 100 feet. Portions of the coast are backed by dunes (e.g., east of Goldsmith's Inlet) and tidal wetlands, while some locations represent low-lying coastal barriers (e.g., Truman Beach). Shorelines fronting the Peconics are irregular and indented by numerous inlets and bays. Coastal areas east of Shelter Island fronted by Gardiners Bay are exposed to a moderate wave climate~ while those west of Shelter Island and along Long Beach Bay have minimal wave energy. The wave energy becomes greater in Little Peconic Bay and greater still in Great Peconic. However, the fetches (length of open water where wind waves can form) are longer in Gardiners Bay than the Peconics. Beaches are generally narrow and sandy and predominate along the eastern shoreline, with the exception of the wetland areas along Long Beach Bay. Bluffs are relatively low and infrequent along the Peconics. Shorelines backed by dunes are limited and specific to Orient Point State Park, which is a spit formation. Tidal wetlands predominate along the western low- energy shorelines, which are the result of the presence of Shelter Island. Numerous barrier spits and shoals exist along the entire bayfront region. B. COASTAL PROCESSES Shoreline configuration is constantly changing as a result of varying hy- drodynamic (water motion, water level, and other forces) and sediment process- es. The evolution of a shoreline can be discussed both in the across-the-beach profile and along the beach, which is often called longshore. This evolution occurs during both normal low wave conditions and storms. During the storms, I-5 the more spectacular changes occur~ but the normal weather conditions act over longer periods of time and are important in understanding beach evolution. The movement of a beach in response to waves is referred to as littoral transport, defined as the alongshore movement of sediments in the nearshore zone by waves and currents. Transport direction is mostly determined by wave steepness, sediment characteristics, and beach slope. Longshore transport of sediments results from the initiation of sediment motion by incoming waves and continued movement due to longshore currents. The magnitude and direction of longshore transport is dictated by the angle of wave approach to the shoreline, sediment characteristics and supply, and available wave energy. Direction and magnitude of longshore sediment transport is highly variable from day to day. Differences in longshore transport result in either accretion or erosion of the shoreline, and are responsible for many of the current erosion hazards along the project coast. Interruption of this longshore movement -- e.g. headlands, inlets, and shore protection structures -- can result in significant impacts on shoreline position. At Mattttuck Inlet, for example, jetty construction and channel dredging to reduce shoaling of the inlet channel resulted in erosion on the east as the sediment supply was interrupted. The across-the-beach profile (Figure I-l) continually adjusts to dissipate the incoming wave energy. Beach response during normal conditions is subtle, as wave energy is easily dissipated by the beach~s natural protective features. The beach will accrete sand from the littoral transport and become wider and higher. At the end of a summer, a beach will normally have stored a large volume of sand. During storm conditions, however, the coast responds to in- creased amounts of wave energy, often leading to the loss of significant quan- tities of beach, dune, and/or bluff material. Figure I-2 illustrates a beach response to wave attache during a storm. The foreshore is eroded and the back- shore is often lost. During large storms, the dune system or bluffs are also eroded. The beach slopes become flatter. Some of the eroded sand is deposited in an offshore bar, and much can be lost offshore. These losses are sometimes (but not always) temporary, except in the case of bluff erosion, which'is a permanent change to the coastal configuration.' 6e95 I I I I I I I I I I i {O~ae Cres! Profile A - Normal ave ac ' n ":'.'.:.~ storm .aves ~rofile ACCRETION Profile O- After storm w~ve .ttoc~, 'Profile Source: U.S. Army Corps of Engineers, Shore Protection Manual, 1984 Figure 1.2 Beach Response During a Storm ~ind~ Winds over coastal regions result in coastal changes through three primary mechanisms: 1) wind-generated waves, 2) wind-induced storm surges, and 3) aeolian (wind-induced) sediment transport. Generation of wind waves depends on the fetch (the distance over water that the wind blows without interruption) and wind conditions (duration and speed). During storm events when extreme wind speeds persist, water elevations at coastal sites may increase as water piles up against the coastline. This effect is a component of storm surge, which often causes flooding and extreme wave attack damages. Aeolian sediment transport is a primary mechanism respon- sible for either the growth or deflation of coastal dunes. Strong winds (gen- erally exceeding 15 miles per hour) must be present to cause significant sedi- ment movement by aeolian transport. The magnitude of aeolian transport is highly dependent on the presence of vegetation and/or moisture, both of which reduce the movement of sediment. A wide beach is also necessary for dune for- mation. Dunes are found in the vicinity of Mattituck and Goldsmith Inlets, but the Town does not have the large dune systems that are found on Long Island's Atlantic shore. Wind data for long periods of record are available from observations at the Brookhaven National Laboratory at Upton, the Suffolk County Department of Public Works and Highways at Westhampton Beach, and the U.S. Weather Bureau at La Guardia Airport for New York City. Short-term data are also available from the U.S. Weather Bureau at Calverton Airport. Average wind conditions for the northeast, southeast, northwest, and southwest quadrants were estimated from the records at the four wind stations. With minor exceptions for the station located at La Guardia, the wind direction distribution for Long Island can be summarized as northeast, 20 percent; south- east, 17 percent; northwest, 30 percent; and southwest, 33 percent. (Wind di- rections refer to the direction from which the wind is blowing.) Winds from the northern quadrant dominate during the winter, and w~nds from the southern quadrant dominate during the summer. The wind velocity'and storm duration during the winter tend to be higher than during the summer. In the summer, the percentage of calm conditions is over 10 percent, while calm conditions drop to under 3 percent during the winter. These values summarize wind conditions in the Long Island vicinity, but may not be directly applicable to Southold I-7 because of their distance (La Guardia Airport) and different topographic set- tings (Upton and Westhampton). Because wind data are not available for coastal areas along the north shore of Long Island, these data must be considered representative. In addition to long-term wind records, wind observations during storm events are important for evaluating coastal changes. Data obtained during storms were available for several locations, including Montauk Point, Block Island, and La Guardia Airport. Table I-1 contains the pertinent maximum re- corded wind velocities for some major storm events. The fastest mile and 5-minute average data are typically used to conduct wave estimates. The most applicable information for Southold are records from nearby open-coast weather stations. Block Island and Montauk Point data, therefore, are suggested for use at Southold; La Guardia wind data are used to augment the records. Table I-1 LONG ISLAND Location Block Island Block Island Eastern End of Long Island .:x.j.R~Vr~DVELOCITY~CO~DS Velocity Date (~h) 21 September 1938 82 21 September 1938 91 21 September 1938 96 Block Island Block Island La Guardia Airport Block Island Block Island Block Island Block Island Montauk Point Montauk Point Montauk Point 14 September 1944 88 14 September 1944 100+ 25 November 1950 94 6-7 November 1953 95 6-7 November 1953 98 31 August 1954 105 31 August 1954 135 12 September 1960 105 12 September 1960 120 6-8 March 1962 68 Type of Record 5-minute average Gust US Weather Bureau wind pattern Fastest mile Gust Gust Fastest mile Gust Fastest mile Gust 5-minute average Gust Gust Waves are created by wind blowing across the water with energy transferred to the water surface. This energy transfer creates perturbations in the water surface commonly referred to as wind waves (see Figure I-3 for a definition of wave characteristics). The waves then travel across water until reaching land, where they expend their remaining energy on the shore. Waves generated by local winds blowing on shore typically reach the shore as steep (i.e., wave I-S Direction of Wove Travel I~ L: Wavelength ,,, Wave Crest--,~! ,,,., :Wove.ei~h~ .!. I ~ LS . ength ~- i ~ Wo,;e Trough / ~' ~ I~egJon I I ! CStillwoter Level ~-----Trough Lenglh ~ i / Region d = Depth Ocean Bottom ~ / Source: U.S. Army Corps of Engineers, Shore Protection Manual, 1984 Figure I-3 Wave Characteristics length to wave height ratio is small) erosive waves called seas. Waves gener- ated at great distances (hundreds to thousands of miles) prior to reaching the shore will decay into long Iow waves referred to as swell. The height, length, and period of wind waves at a coastal site are deter- mined by the fetch, wind characteristics, decay distance, and water depth. In general, increases in fetch, wind speed, and duration result in larger wind waves. Water depth, if shallow enough compared with the wave height and peri- od, will affect wave characteristics, with wave breaking beginning when the wave height is roughly 80 percent of the water depth. Waves generated by wind are characterized by many combinations of height, period, and direction. This combination of waves is referred to as the wave spectrum, which is often char- acterized by representative wave parameters (wave height and period). Wave conditions at any given location over a period of time can be described through use of a wave spectrum, where characteristic wave conditions are referred to as the wave climate. Wave data for the north shore of Long Island have never been rigorously collected. Waves that affect the shore are generated by local winds, as Long Island and Block Island stop ocean swells from entering Long Island Sound (Davies et al., 1973). Given the orientation of the Southold Long Island Sound shoreline, winds from the northern quadrant and the west are primarily respon- sible for wind waves along the coast. In the Peconios, the fetch is limited compared with the Long Island Sound side, but waves large enough to cause ero- sion can occur except within the creeks. Fishers Island is somewhat exposed to ocean wave conditions from the southeast; however, waves traveling from the ocean are affected by Montauk Point and Block Island. In general, the wave climate at shorelines along Long Island Sound (Fishers Island) are moderate, whereas shorelines along the Peconics and the majority of Gardiners Bay are less energetic. USACE (1969) summarized fetch distances for the Long Island Sound coast, that were augmented with approximations for the Peconics and Fish- ers Island. Estimates for these locations are for the maximum single fetch distance rather than the average distances used in wave calculations. ~he fetch distance for Fishers Island corresponds to the breadth of Block I~land Sound, and excludes the narrow opening to the open ocean. These fetch dis- tanoes are summarized in Table I-2~ Wave heights and periods for shallow water waves (waves interacting with local bathymetry) were hindcast using techniques given in the Shore Pro~ection Manual (1984). Information used for these compu- tations indluded water depths of 50 (no symbol) and 100 feet (with symbols), I-9 Table I-2 Location Wildwood Mattituck Inlet Hashamomuck Beach Orient Point Fishers Island* East Shelter Island Little Peconic Great Peconic SOu'£HOLD aura FETCH DISTANCES Fetch Distance (miles) w-~im~m Fetch Northwest Northeast Southwest Southeast (miles) 27 30 30 50 20 50 49 14 49 17 11 17 20 20 45 45 6 6 10 10 * To the Race that restricts short period wind waves but not swells fetch distances from 10 to 70 miles, and wind speeds from 10 to 120 mph. The results are shown in Figures I-4 and I-5. While these results are not applica- ble to any particular location along the project shoreline, they are represen- tative of the relationships between various wave generation parameters. Vater Levels Elevation of the water surface can be considered as a long-term average dependent on the volume of water contained in glacial form or as a short-term change in water elevations as a result of astronomical tides, storm impacts, and precipitation and ice melt (for rivers and small bays). The fluctuations resulting from the combined effects of astronomical tides and storm surges, and the effect of sea level rise on global ocean levels are of primary importance for this report. Astronomical Tides Tides are created by the gravitational forces exerted by the moon and, to a lesser extent, the sun. These forces of attraction -- coupled with the fac~ that the sun~ moon, and earth are always in motion relative to one another -- cause oceans to be set in motion. These tidal motions are very long period waves, and result in the periodic rise and fall of water levels along the coast. The phasing of high and low tides is variable and important to the level of wave attack along the shoreline. High tides in conjunction with 1-10 35 3O 25 15 I0 0 10 20 ~0 40 50 60 70 80 go 100 110 120 WIND VELOCITY (mph) ...... 70 mdes Figure I-4 Estimated Wave Heights I1 I0 g 4 3 2 I0 80 90 100 110 120 WIND VELOCITY (mph) -- I0 redes ---- ~ 40 miles · 10 miles Figure I-5 Estimated Wave Period I I I I I t I I I i I i I I i I i i I strong onshore winds~ for example, cause increased shoreline erosion as large waves break closer to shore in deeper water, thus exerting greater forces on the shoreline. Tides in Long Island Sound are semi-diurnal (occurring twice a day), and the height increases from east to west due to the narrowing of the Sound, as the area of the Sound lessens and the volume of water remains unchanged. Tidal ranges for points within Southold are shown in Table I-3. Tides are given as spring and mean tide for each location. The mean tide is the average tidal range, and the spring tide is the tide that occurs at or near the time of the new or full moon, which rises the highest and falls the lowest from mean sea level. Storm Surges Table I-3 SOuTuOLD TIDAL HANGES Tidal P~nge (feet) Location Mean SDrin= Mattituck Inlet 5.0 5.8 Herren Point 4.0 4.6 Truman Beach 3.4 3.9 Orient Point 2.5 3.0 Southold 2.3 2.7 New Suffolk 2.6 3.1 Hurricanes and tropical storms are large wind fields, driven by central low pressures and temperature gradients. These storms cause the water eleva- tion at the shoreline to rise and flood the land. Several factors are in- volved: wind stress, wave setup, barometric pressure reduction, and the Corio- lis force. In response to the earth's rotation, the Coriolis force causes water currents to deflect to the right in the northern hemisphere. These fac- tors have caused increases in water elevations in excess of 13 feet above nor- mal in Long Island Sound. Wind stress and barometric tide are of primary importance to the magnitude of storm surge. Hsigh= of the wind stress depends on wind speed and direction~ fetch, bathymetry, and nearshore slope. Basically, the wind drives the water into the shore faster than it can return to open water. Either the water piles 1-11 up until the wind reduces in force, or the water reaches such height that grav- ity forces it to return to open water. The barometric tide is the increase in water surface elevation within the storm's low-pressure system. The higher barometric pressure outside of the storm forces water in toward the lower baro- metric pressure at the center of the storm. A Coriolis water level rise occurs when the storm forces currents to flow along the shoreline. This component of storm surge occurs in Long Island Sound, but is not particularly large. Howev- er, it can also reduce the storm surge when the current direction causes the Coriolis force to be directed toward Connecticut. The final component is the wave set-up, which occurs in the surf zone when wave momentum transfers from the waves to the water column. This component is important for large storm waves where wave set-up may be as much as 20 percent of the breaking wave height. Factors that eventually determine the magnitude of the storm surge are the stage of the astronomical tide (storm surge is superimposed on top of the tide level), storm intensity, forward storm speed, and angle of storm track to the shoreline. Shoreline configuration is also important in determining surge elevations, much as shoreline configuration affects astronomical tides. This effect is simply the funneling of water that occurs when there is a constric- tion between two land masses. This occurs in Long Island Sound, causing water levels in the western portion of the Sound to exceed those in the eastern sec- tion. Increased fetch distances for wind setup also contribute to this effect. Storm surge frequency relationships, available for many locations, are either compiled and estimated from historical data or obtained through predic- tive techniques. These frequency relationships describe the annual probability of occurrence for any particular water level event. The highest tidal height ever observed was 13.3 feet above Mean Sea Level (MSL) at Willets Point during the hurricane on September 21, 1938. At Port Jefferson Harbor during the hur- ricane of August 31, 1954, a water surface elevation of 9.45 feet above MSL was recorded. No extreme water level predictions have been prepared for the Town of Southold, but extreme water level predictions for London, Connecticut are considered to be representative for the Long Island Sound shore of Southold. This is shown in Figure I-6. The highest predicted water level is 14 feet above MSL, close to the physical maximum that can occur. The more commonly used 100-year flood level is 10.7 feet above MSL. Although this is called the 100-year flood, it is a statistical measure, and that water level has never been measured in Southold. Additionally, if it does occur, water could rise to 1-12 I I I I i I I i I I I I I I I I I i i 6.95 FREQUENCY IN YEARS DESIGN HURRICANE TIDE EL. 14.0 j~ 1938 ADJUSTED FROM A 225 YEAR PERIOD [] .....--~ 1'19;A[USIEDiROIA22/YEARPERIOD54 DJ T F M 5 ~'-- '~-- '-'u ~. TO A 146 YEAR PERIOD HIGH SPRING TIDE MEAN SPRING HIGH WATER MEAN H GH WA~R MEAN S~ ~VEE 6 5 )4 3 2 PERCENT CHANCE OF OCCURRENCE PER YEAR 7 > 7 7 > a Elevation Based on Recording Tide Gage Reading or High Water Marks Referred to a 225 Year Pedod, July 1938-December 1960, Inclusive o Elevation Based on High Water Marks Referred to a 146 Year Period, 1815-1960, Inclusive Curve prepared by New England Division, Corps of Engineers Figure I-6 Extreme Water Level Predictions I I I I I I I I I I I 1 I I I i I I i this level more than once in a given year. Having this storm surge once does not mean that it will not occur for another 100 years. Sea Level Rise Sea level rise can be separated into two categories: 1) eustatic rise (change in ocean elevation) and 2) relative rise (change in ocean level rela- tive to adjacent land). Relative rise includes changes in both ocean and land levels, thus including eustatic sea level changes. Causes of sea level rise include changes in sea floor spreading, ocean and land area changes, tectonic plate movement changes, thermal effects, ocean sedimentation, glacial charac- teristics, hydro-isostasy, sediment isostasy and compaction/subsidence, ocean surface topography and temperature/salinity effects, changes in the geoid, geological faulting, and climatic effects (GTFII 1994). Scientific evidence suggests that water levels during the peak of the ice age were at least 450 feet lower than they are now, because of water contained in glaciers. As the glaciers melted, sea levels rose about 0.3 inches per year. Along the New York coastal region, the relative sea level rise over the last 100 years (accounting for land rebound and sediment accumulation) is esti- mated to have been from 0.04 to 0.14 inches per year. Historical sea level rise rates are anticipated to continue, but there is much uncertainty about the possibility of an increase. The effect of excess fossil fuel emissions, which leads to global warming, would be to accelerate glacial melting. Past esti- mates have been for sea level increases from 2 to 7 feet in the next century; more recently, these estimates have been revised to less than 2 feet. Further research im required to refine these estimates; thus, use of non-historical sea level rise rates is highly subjective. Despite the difficulties associated with predicting sea level rise, espe- cially accelerated rates, it is an important factor in determining future ere- mien patterns. As sea levels increase, low-lying areas become more subject to flooding; magnitude of wave attack on previously protected shoreline locations increases; and wetland areas could become inundated, exposing current inland locations. These conditions are important in the Southold region for several reasons. First, the bases of bluffs are particularly susceptible to sea level increases, as current protective beaches would be rendered ineffective in pro- tecting against wave attack. Once bluffs are exposed to more direct wave attack, bluff recession would proceed at a relatively rapid rate. Therefore, 1-13 I I i I I I I 1 I I I I ! I I I I I I the rate of bluff erosion and shoreward migration along Southold's Long Island Sound shore is likely to increase in the future. In addition, development in low-lying areas along the Town shoreline~ such as Fishermans Beach, would be subject to increased flooding and landward movement or destruction of coastal beach and dune systems. Finally, current protective measures -- e.g. bulk- heads, revetments, and groins -- would be destroyed or at least rendered less effective, and current Federal Emergenc~ Management Agency Flood Insurance Rate Map boundaries would be affected. Nearshore currents play an important role in the evolution of coastal en- vironments. Currents are driven by four mechanisms: 1) spatial differences in water surface elevations, 2) wind, 3) angled wave approach to the shoreline, and 4) river discharge. Significant currents can be generated by tides at inlets to bays or lagoons or at entrances to harbors. Currents at these con- stricted entrances flow inland when the tide is rising (flood tide), and flow outward as the tide falls (ebb tide). USACE (1969) reports that maximum cur- rents along the north shore of Long Island typically range from 0.5 to 3.5 knots during floodtide and 0.6 to 4.3 knots on the ebbtide. Average currents along Southold were reported as 1) Terry Point -- 2.7 knots (flood) and 3.2 knots (ebb); 2) Mulford Point -- 1.9 knots (flood) and 2.3 knots (ebb); and 3) Plum Gut -- 3.5 knots (flood) and 4.3 knots (ebb). High river discharges or strong winds can alter these velocities, which can be seen in Long Island Sound when strong winds from the west slow the ebb tide and allow the flood tide to bring additional water and subsequent extreme water surface elevations into the Sound. Currents are created as wind blows over the water's surface, and stress on the surface initiates movement in the direction of the wind. When the surface current reaches a barrier, such as a coast, water piles up against the land. This piling up of water, which is called wind setup and is a component of storm surge, can create significant increases in water elevation when it occurs dur- ing storms. Another important mechanism in the nearshore region is the generation of alongshore currents caused by waves approaching the shoreline at an angle. This results in a gradient in nearshore surface elevations and induced currents, which tend to dominate during calm periods. Tidal current velocities 1-14 I I I I I I I I I I I I I I I I I I I rapidly decrease as the shoreline is approached, and therefore, any littoral movement is usually the result of wave action. This holds true for Long Island Sound shorelines east of Port Jefferson, whereas the western areas are subject to increased tidal ranges, which cause higher tidal current velocities. Sed~.ment Characterlstics and Supl~ly Shoreline condition, in general, is affected by the amount of sediment entering and leaving an area. Sediment supply is a major factor in determining whether a coastal region is eroding, accreting, or stable. Along the Southold coastal front, the primary sediment source is the glacial bluffs. Sediments on most beaches range from fine sands to cobbles, with occasional large boulders. Wave erosion of these bluffs -- along with the impacts of surface drainage, rainfall, ground water seepage, and vegetative cover, and subsequent bluff failure -- introduces large amounts of sediment to the littoral environment. This material is then transported alongshore to other shoreline reaches at a rate referred to as the longshore sediment transport. The direction of longshore transport can often be deduced from the study of existing landform. As sediment is transported in the nearshore and beach, human structures can interrupt this flow. Sediment is deposited on the updrift side, and the downdrift side suffers a loss of sediment. Sand can also be lost offshore into deeper water because of these human structures. On the Long Island Sound shore of Southold, the predominant direction of longshore trans- port is toward the east. The jetties at Mattituck and Goldsmith Inlets inter- rupt this flow, leading to accretion on the west side of the inlets and erosion on the east side. Along the rest of the Long Island Sound shoreline, the head- lands and points interrupt the flow during low wave periods, forming cells between the points. During storms, longshore transport occurs around the points, primarily from west to east. This storm movement is thought to be the dominant force in determining the direction of longshore transport on South- old's Long Island Sound shoreline. On the Peconic Bay shoreline, the direction of longshore transport varies greatly. The orientation of the shoreline dif- fers by up to 180°. Therefore, one storm causes longshore transport in two or more different directions on the Peconic Bay shore. Additionally, the many inlets, with and without jetties, interrupt the longshore transport. The Peconic Bay shore has many small cells for longshore transport, and cannot be 1-15 ! ! described in general as the Long Island Sound shore can. The volume of sediment transported is an important parameter, and its analysis requires a large amount of data. The problem needs to be studied in all three dimensions to de~ermine how many cubic yards of sediment are con- tained in a foot of beach. Several seasons are needed over which to obtain these data beach profiles. The profiles can be supplemented with aerial photo- graphs to determine changes in form, but the photographs do not show elevation changes. Without collecting and analyzing these data, only the most general estimates of sediment volume and change in the longshore transport can be made. Storms Shoreline changes result from both day-to-day coastal processes and storm- induced coastal processes. It is not certain which of these change mechanisms is most important over the long term; however, it is clear that both play an important role in coastal conditions. While shoreline changes under normal conditions are nearly imperceptible, those that take place during a storm event are often distinct. As discussed earlier, storm winds typically generate high, steep waves in conjunction with the storm surge. Increasing water levels expose higher por- tions of the beach to wave attack, and allow large waves to pass over the near- shore without breaking. At the point where the breaking occurs, which is often close to shore, the remaining surf zone is insufficient to dissipate the in- creased wave energy. This excess energy then causes erosion of the beach, berm, dune, or bluff. The eroded material is carried offshore in large quanti- ties and is deposited in a bar formation that grows to the point where the large storm waves break farther offshore, spending their energy in the surf zone. Ultimately, these storm-induced processes establish an offshore bar that provides protection from storm wave energy. Eroded beach material will often return to the beach berm during normal conditions when waves assume an accretional character. This stage is referred to as post-storm recovery. This recovery is fairly slow in Long Island Sound because there are few long period swells to move sand from deeper water onto the beach. Erosion of dunes is more severe, requiring re-establishment through aeolian processes. Bluff erosion is most problematic because it is permanent -- no post-storm recovery is possible. Although post-storm recovery does take place, each storm removes some amount of beach material, decreasing its protec- 1-16 rive capabilities. Finally, storm waves and water levels can also damage coas- tal structures and flood low-lying areas. Although damage resulting from these mechanisms is more immediately evident and financially harmful, erosion of the coastal region is the avenue through which other storm-induced damages are initiated. Along the coastline of New York State, two types of storm events are of significance: 1) tropical storms (originating in the tropics) typically affect the New York area from July to October, and 2) extratropical storms (originat- ing outside of the tropics), which are primarily less intense winter storms. Hurricanes are the most powerful tropical storms to reach the New York area, with wind speeds in excess of 74 mph. Historically, New York has been hit by a number of hurricanes: 24 storms have been recorded in the New York coastal region. Table 1-4 lists several hurricanes. Because of the cold water in the New York region, hurricanes move faster in the forward direction, which increases the apparent wind speed. Many meteorologists also believe that it is improbable that the New York area could be subject to a hurricane more powerful than Class 4 (winds from 131 to 155 mph). Damage from this class of hurricane, coupled with high forward speed~, would be tremendous. Alternatively, the high forward speeds and relatively limited size of hurricanes reduce damages as a smaller area is impacted and storm duration is limited. Furthermore, storm damage magnitudes can be traced to the concurrence of high astronomical tides and the storm surge, which act together to allow large waves to penetrate far- ther inland, resulting in extreme erosion and flooding. The relatively short duration of hurricanes often results in reduced damages, as water levels are reduced by storm impact at a low tidal level. Recent hurricanes along the New York coastal region have not resulted in significant erosion and flooding be- cause maximum storm surges have coincided with low tide, as opposed to recent extratropical storms that have occurred with high tides. Extratropical storms originate outside of the tropics, usually in the mid- to upper-latitudes during winter months. More commonly referred to as north- easters, these storms are less intense than hurricanes but have localized winds that often reach hurricane strength. Extratropical storms cover large areas and are slow moving; typical storm durations last for a period of days. USACE (1969) states that 65 moderate to severe northeasters have impacted the New York coastal region over the 100-year period before 1965. More recently, a series of severe northeasters has impacted the New York coastal region in October 1991, December 1992, March 1993, and December 1994. Table I-4 lists 1-17 the severe extratropical storms that have had significant impacts on the New York coastlines. Table I-4 HISTOP, ICAL STORMS AFFECTING THE ~w YORK COAST DaCe Storm T~pe Name September 14, 1904 September 8, 1934 September 21, 1938 September 14, 1944 August 31, 1954 September 12, 1960 August 6, 1976 September 27, 1985 August 19, 1991 March 3, 1931 November 17, 1935 November 25, 1950 November 6, 1953 March 6, 1962 February 6, 1978 March 28, 1984 October 30, 1991 December 11, 1992 Hurricane Hurricane Hurricane Hurricane Hurricane Hurricane Hurricane Hurricane Hurricane Extratropical Extratropical Extratropical Extratropical Extratropical Extratropical Extratropical Extratropical Extratropical Carol Donna Belle Gloria Bob Northeasters are similar to hurricanes in that damage to coastal areas oc- curs from erosion and flooding stemming from high winds, large waves, and in- creased water levels. Although wave heights and storm surges from extratropic- al storms are less severe than from hurricanes, erosion and flooding can equal or exceed hurricane-induced levels. Increased storm duration is the primary factor that causes large coastal damages during northeasters. Because they last days rather than hours, northeasters persist over numerous tidal cycles, continually attacking coastal areas with several peak water elevations. In addition, continued strong winds can trap much of the ebb tidal flow within Long Island Sound, allowing flooding tides to augment existing high water and cause extreme water elevations. Damage from hurricanes and northeasters is highly dependent on storm in- tensity and duration. However, the location of a storm relative to Long Is- land's north shore is another major factor. Storm location is linked to storm characteristics that determine where, relative to the storm movement, the most 1-18 severe conditions exist. Tropical cyclones are characterized as small fast- moving storms consisting of a counter-clockwise spiral about the center (the "eye") of the storm. This forward speed increases the apparent wind speed. Winds to the right of the eye are most severe and are parallel to and rein- forced by the forward storm speed. Therefore, since tropical storms travel in a general northerly direction, south-facing coastlines are usually subject to the greatest hurricane forces. North-facing coastlines, however, are somewhat protected from the strongest storm impacts~ Similarly, extratropical storms are characterized by a counter-clockwise spiral directed toward a central Iow pressure center. Wind direction and ve- locity at a given coastal location depend on the relative location of the storm track. The course of a northeaster to the east of the Sound is the most impor- tant factor for the north shore of Long Island, where winds blow initially from the northeast. Wind direction changes with storm movement to north-northwest winds as the storm passes, and produces large wave heights and wind setup along the north shore~ Northeasters, with winds from the east occurring through numerous tidal cycles, have historically had the greatest effect on the Long Island Sound coastal region because of their long duration. Introduction Construction of shoreline structures and dredging operations are a major factor affecting coastal erosion and flooding. Engineered structures -- e.g. groins, jetties, bulkheads, breakwaters, and seawalls -- can halt, slow, or exacerbate coastal erosion. Structures introduced to the coastal environment to alleviate one problem often cause more severe problems, because the struc- tures may have multiple influences on coastal processes. Other efforts, in- cluding beach nourishment and dredged material placement, can be undertaken to augment the coastal system by introducing additional littoral materials to the coastal system without adversely affecting other locations. As beach erosion and accretion, inlet opening and closing, bluff erosion, bay and wetland envi- ronmental changes, and other changes to the coastal regime are natural and ongoing processes~ any alteration to the natural system will affect its dynamic stability. To show the amount of effort and money expended to maintain an 1-19 engineered approach, Table I-5 presents the dredging that has been performed at Mattituck Inlet. Much of the dredged sand was removed and used by the town. Human intervention in the coastal environment -- for the prevention of flooding and erosion, reduction of inlet shoaling, or land development -- is a short- term attempt to engineer a solution to a problematic coastal condition. These interventions are often poorly engineered and fail to accommodate the dynamic nature of the coastal environment. Table I-5 SO]4WARy OF THE VOLU~ES OF '£H~. SAND KE~OVED I~OM T~E A~R&~TEST OF JETTIES OF THE NATTIT~CK INLET: 1960-1975 Yards Year Removed 1975 1974 1973 1972 1971 1970 1969 1968 1967 1966 1965 1964 1963 1962 1961 1960 TOTAL 3,965 364 3 356 9 502 8 532 7 208 6 482 15 914 24,914 25,808 26,534 20,032 36,098 14,734 17,694 23.214 244,351 Source: New York Sea Grant Service. Construction of either hardened coastal structures (e.g. bulkheads, groins, jetties, or seawalls) or soft methods (beach nourishment, vegetation, or dune building) are attempts to stabilize beaches, bluffs, inlets, or barrier landforms. Placement of hardened structures requires periodic maintenance and mitigation, and often results in significant negative impacts. These can in- clude downdrift erosion and loss of sediment offshore. Navigational needs also 1-20 lead to large disturbance of natural systems. Table I-6 lists the number of projects and dredging volume performed out by the Town of Southold in Goldsmith Inlet and on the Peconic Bay side. Soft structures -- which have less impact on the natural system -- may require frequent maintenance and could provide less protection against the problem in question. These soft solutions to erosion may not be feasible for individuals, as large construction may be required for proper performance. Although feasible and practical engineering of the coastal environment is pos- sible, construction must consider the range of impacts resulting from such solutions. As discussed below, placement of dredged materials on adjacent beaches is an important soft engineering approach in Southold. Hardened Structures Bulkheads, revetments, and seawalls are common along the coast of New York, especially the northern shorelines of Long Island. The function of these shore-parallel structures is to retard erosion of the upland while sacrificing the beach and nearshore areas. The potential for negative impacts from these structures is apparent at many locations. However, placement at sites with adequate sediment supplies can mitigate these impacts. The jetties at Matti- tuck Inlet have caused severe erosion on the east side, which has lessened as sediment has either bypassed the inlet or was transported from further east and deposited behind the east jetty. To illustrate possible negative impacts, a shore parallel structure placed at a location that experiences chronic long-term erosion is analyzed here. The structure essentially removes the upland sediments from the coastal regime, thereby pinning the shoreline to a given location. Under natural conditions, the upland would provide the sediment necessary to maintain a protective beach, but would result in permanent loss of the upland. The structure pins the shoreline position but does not alleviate the erosional condition. Nature often finds an alternative sediment source, which results in accelerated ero- sion of the beach directly in front of and adjacent to the structure. Follow- ing or prior to the loss of protective beach, beach nourishment is necessary as a mitigation effort. Should the situation not be mitigated, the beach might totally disappear, resulting in direct wave attacks on the structure. This 1-21 Table ~-6 SUmmARY OF TOWN OF SOuTHOLD DREDGING PROJECTS Reach Proiect Name 1 Mattituck Creekd 1 Long Creek (part of Matti- tack Creek) 2 Goldsmith Inletb Subtotal 2 North Sea 5 Gull Pond Subtotal 5 Sterling Basind Subtotal 6 Mill Creek Subtotal Town Creek/Harborc Subtotal Jockey Creekc Subtotal 7 Goose Creekb Subtotal Cubic Dates Yards Dredged Dredged 1955 1,595,400 1967 13,000 1977 4,000 1980 3,700 1982 6,000 1985 2,640 1987 4,800 16,340 1992 12,980 1959 177,200 1960 28,500 1970 29,000 1979 23,300 1983 1.000 259,000 1959 163,900 1963 129,200 1976 12,000 1992 4,490 305,590 1963 66,300 1968 2,700 1975 6,000 1979 4,000 1981 4,500 83,500 1959 23,200 1959 93,400 1976 9,000 125,600 1959 23,200 1959 93,400 1976 9,000 125,600 1959 46,700 1967 75,200 1968 11,100 1976 6,000 139,000 Nethod of Soil Displacement Upland site of Matti- tuck Creek and Long Creek Beach nourishment Beach nourishment be- tween Gull Pond and Sterling Basin Formerly used wetlands by cemetery, now use back side of inlet for beach nourishment Upland on island to the west Beach nourishment to the west Beach nourishment to the west Formerly upland by Bay- view Avenue, now beach nourishment Res of Water Depemdent Facil~ties 3 marinas and park district boat slips and ramp Matt-A-Mar Marina is at intersection None Town beach, docking and boat ramps 4 marinas and a sailing club 3 marinas Marina near mouth of creek and town ramp on bay Marina Ramp 1-22 I I I I I I I I I I I I I I I I I I I Table I-6 (Continued) SUN~A~Y OF TO~N OF SOoTHOLD DREDGING PROJECTS Reach Project Name 7 Cedar Beach Subtotal 7 Corey Creekb Dates Dredged 1979 1980 1981 1982 1983 1984 1985 1986 1987 1963-64 1967 1972 1981 1983 1984 1986 1987 Subtotal 7 Richmond Creek Subtotal 8 Broadwater Covea Subtotal 1959 1964 1967 1972 1983 1995 1966 1976 1982 Cubic Yards Dredged 12,400 1,900 9,700 1,700 1,700 1,900 1,440 2,880 1,920 35,540 345,600 23,900 7,600 10,200 800 3,500 18,600 5.040 315,240 123,000 82,800 25,100 5,500 15,300 20.000 271,700 434,400 11,000 10,200 455,600 Method of Soil Displacement Beach nourishment to the west Types of Water Dependant Facilities Marine Tech- nology Dept. of Suffolk County Commu- nity College Formerly upland and now Ramp beach nourishment Beach nourishment on both sides of inlet None Upland disposal adja- cent to creek Formerly upland on 2 sites, now beach nour- ishment to the west of inlet Marina 1-23 Table I-6 (Continued) Reach Protect Name 8 Little Creekb 8 Mud Creeka Subtotal Subtotal 8 East Creeka SUGARY OF TO~N Subtotal 8 Wickham Creek Subtotal 8 Schoolhouse Creek Dates Dredged 1967 1968 1975 1976 1978 1979 1980 1981 1981 1982 1983 1983 1984 1984 1985 1986 1987 1991 1992 1993 1966 1976 1982 1987 1992 1966 1976 1982 1966 1972 1979 1981 1982 1983 1984 1985 1986 1987 1992 1976 OF SOu'ruOLD DREDGING I~OJECTS Cubic Yards Dredged 51,000 3,700 5,000 40,000 4,000 5,000 2,400 2~400 5,500 7,000 2,400 2,300 2,400 6,000 3,120 5,760 8,400 4,000 4,740 5,000 170,120 434,400 11,000 10,200 6,600 2.910 465,110 434,400 11,000 10,200 455,600 48,300 10,000 3,600 1,700 2,200 1,900 1,400 1,440 2,640 2,640 1,500 77,320 12,000 Hethod of Soil Displacement Beach nourishment on both sides of inlet Types of Water Dependent Facilities Ramp/Moorings Formerly upland on 2 sites, no beach nour- ishment to the west of inlet None Formerly upland on 2 sites, now beach nour- ishment to the west of inlet None Beach nourishment to the west Marina Beach nourishment Marina 1-24 Table I-6 (Continued) S'OM~ARy OF TO~N OF SOuT~OLD DRKnGING PROJECTS Reach 8 9 9 l~oject Name New Suffolk Subtotal West Creekb Subtotal Halls Creek¢ Subtotal Deep Hole Creek Dredged 1977 1979 1980 1981 1982 1983 1984 1985 1986 1987 1993 1966 1976 1982 1979 1980 1964-65 1972 1975 1976 1980 1980 1982 1983 1987 1991 1993 Subtotal Subtotal 9 James Creek 1964-65 1979 1980 1983 1985 1986 Cubic Yards Dredged 4,000 1,500 1,000 2,000 3,300 1,000 1,800 2,500 1,250 1,500 2,000 21,850 92,500 9,000 2,800 101,800 17,400 4,200 21,600 243,500 21,100 4,000 14,000 5,000 10,000 8,800 6,300 7,680 4,600 10,600 335,580 272,500 3,000 6,700 9,400 5,250 1,570 298,420 Method of Soil Displacement Types of Hater Dependent Facilities Beach nourishment on Boat ramp town beach to the south Beach nourishment on both sides of inlet Ramp Beach nourishment to None the east Beach nourishment on both sides of inlet None Formerly upland to the east, now beach nour- ishment on both sides of inlet 2 marinas 1-25 I I I I I I I I I I I I I i I I I I I Table I-6 (Continued) SI~4aRy OF TO~N OF SOuTHOLD DHEDGING PROJECTS Cubic Dates Yards Method of Soil Reach Pro¶ect Name Dredged Dredged Displacement 9 Brushs Creek 1966 86,400 Beach nourishment on Marina 1975 7,500 both sides of inlet 1979 5,000 1980 1,900 1981 5,800 1983 1,500 1984 4,800 1985 6,750 1986 3,000 1991 3,000 1992 1,530 Subtotal 127,180 10 West Harbor 1971 43,100 Dumped at sea (Fishers Island, channel connect- lng to federal project) -- Wunneweta Lagoon 1991 2,700 1993 1,000 46,800 Subtotal Types of ~ater Dependent Facilities TOTAL 5,875,470 Broadwater Cove, Mud Creek, and East Creek were dredged as one project in 1966, 1976, and 1982. The Suffolk County Department of Health Services has determined that dredging Goldsmith Inlet was necessary in 1985 to protect the public health. Jockey Creek and Town Creek/Harbor were dredged as one project in 1959 and 1976. Mattituck Creek and Sterling Basin are federally authorized projects. So~Tces: Analysis of DredginE and Spoil Disposal Activity Conducted by Suffolk County, County of Suffolk, New York, Historical Perspective and a Look ~o ~he Furure, Suffolk County Planning Department, October 1985; Annual Environmental Report, Office of the Suffolk County Executive, 1987, 1988, 1992, 1993, 1994. 1-26 I I I I I I I I I I I ! I I I I I I I condition often leads to structural failure and severe erosion of the upland that can even exceed that which would have occurred had no protective measures been constructed. Breakwaters are hard structures that are offshore and parallel to the shoreline and that act to reduce the wave energy behind the breakwater before it reaches the coast. By reducing the wave energy, breakwaters allow littoral materials to deposit, which leads to the formation of a protective beach. Ac- cumulation of beach material behind the breakwater reduces the littoral mate- rial available for other shoreline reaches unless beach nourishment or other mitigation measures are undertaken. The very large rocks that can be found on Southold's beaches o~ just offshore serve as breakwaters on a very small scale. Accretion occurs just behind them. Shore-connected and perpendicular structures, called groins, are used along many shorelines~ These structures intercept littoral material, which results in the accumulation of a beach updrift of the groin. Downdrift of the groin, however, the littoral material is reduced, which often leads to erosion. As with other coastal structures, beach nourishment can mitigate this impact. One mitigation method is a series of groins, with beach nourishment filling in the groin compartments. Since the groin compartments are at capacity, long- shore sediments can bypass to downdrift beaches, thus minimizing negative im- pacts on the littoral supply. However, the groins must not be constructed in such a way that the sand is transported offshore and lost from the littoral system. This distance offshore is related to the width of the surf zone under normal conditions, which -- in an area like both sides of Southold -- can strictly limit the allowable groin length. The groins on the Peconic Bay shore of Southold provide illustrations of every type of groin field imaginable. Stone, concrete, steel, and wood have all been used as construction materials. The length~ height, and spacing of the groins have varied from very short, low, and closely spaced, to a single high groin sticking out into the middle of the bay. These groin fields are described in the next chapter, where their effec- tiveness is.[partially] assessed. However, each set of groins would have to be individuall~ studied to accurately estimate their usefulness and their effect on neighbors. Jetties are another shore-perpendicular structure used to stabilize inlet positions and reduce channel shoaling. Littoral material is intercepted by jetties in a manner similar to groins. However, the negative effects of jet- ties on the downdrift shorelines relative to natural inlets and frequent 1-27 I I I I I I I I I I I I I I I i I I I channel dredging are of greater magnitude. Jetty-stabilized inlets intercept a great deal of sand, and a series of jetties increases this effect, decreasing the volume of sand traveling in the downdrift direction. Inlet stabilization also appears to deposit larger volumes of sediments in ebb and flood tidal shoals compared with natural inlets. In natural inlets, sand is distributed along the ocean and bay shorelines as the inlet migrates alongshore, which reduces the volume of material trapped by the inlet. Natural inlets allow more material to bypass to downdrift sections; therefore, whether jetties are pres- ent or maintenance dredging alone is used, inlet maintenance leads to downdrift sand deficits. Many jetties have been built at the mouths of the inlets on the Peconic Bay shore. These' jetties are described in the next chapter, where some assessment of their effectiveness is given. However, each inlet needs to be individually studied to accurately estimate its effects. Soft ~n~ineerinm Solutions Soft structures are often preferable to hardened structures, and represent an attempt to work with the natural system by augmenting its natural defenses. Soft engineering solutions include beach nourishment (placement of beach sedi- ments to create a larger protective beach and dune system), beach shaping, sand fencing (to help the dune-building process), and vegetation (to stabilize ex- isting dunes or trap additional wind-blown sand). These soft engineering solu- tions are often combined very successfully with hard engineering solutions. Beach nourishment is accomplished by delivering sand to the beach or dune from either an offshore or upland site. This is a temporary solution to erosion and flooding problems, since the placed material is sacrificial and only offsets existing erosion problems. Although this method requires frequent maintenance, it has few detrimental environmental consequences. Large-scale beach nourish- ment is often augmented with coastal structures, when there is severe long-term erosion (greater than 3 feet per year, typically). Beach nourishment is usual- ly less expensive, than hardened structures; however, should insufficient mate- rial sources be unavailable or projects be undertaken by local interests, costs may increase. Beach nourishment is an effective mitigation technique, whether or not combined with coastal structures or inlet dredging and stabilization. At inlets, bypassing of materials from either updrift beaches or channel dredg- ing operations to downdrift beaches is an effective and feasible solution to reducing downdrift erosion. Beach nourishment -- combined with breakwaters, 1-28 bulkheads, or groins -- often improves the effectiveness of these structures by introducing additional material to the littoral system. Placement of sand or dredged materials on a beach requires a permit from the New York Stat~ Department of Environmental Conservation (DEC), who have been hesitant to issue these permits. DEC is concerned about the loss of pro- ductive wetlands if the materials are not placed carefully. In the past, they have required upland placement of the materials. As discussed in Chapter VI, "Implementation Options," the Town needs to have ongoing coordination with DEC and Suffolk County to determine the best location to place dredged materials. A long-term relationship with DEC could allay their concerns about loss of wetlands and allow the dredged materials to be returned to the coastal system. Beach scraping augments dune profiles and beach berm widths to provide additional recreational beaches and protection against flooding. The technique consists of removing sand from the nearshore and scraping it up on either the berm or dune. It has been questioned whether beach scraping is an effective means of preventing erosion. Although increasing the volume of the dune pro- file is a practical way to create additional flood protection, the steepening of the beach face may actually increase erosion and loss of beach material dur- ing storms. Beach scraping has also been described as an effective tool for dune building that, when properly conducted, leads to no significant negative impacts. However, it introduces no additional beach material to the system, and its effectiveness in providing protection in eroding areas is therefore limited. Sand fencing and establishment of vegetation are other techniques used to provide additional flood protection by increasing dune volumes. These attempts at dune restoration use wind-driven sediment transport to capture necessary sediments. This approach seems to have been successful at New Suffolk. Since this is an environmentally sound and low-cost effort, many communities under- take dune restoration projects. Increased dune volume protects upland areas from flooding during storm events and reduces beach erosion by acting as reser- voirs of additional beach material. Because of frequent erosion of the dune during storm events, t~e success of dune building projects depends on continued effort and vigilance. A soft engineering solution that is often in conjunction with jetties is sand bypassing. As sand accumulates on the updrift side of the jetty, it is periodically dredged or mined and then placed on the downdrift side of the jetty. Sand bypassing prevents erosion on the downdrift side and large 1-29 accumulation of sand on the updrift side. The littoral system, if the bypass- ing is done correctly, stays in equilibrium. Land Use Human activity brings additional forces into the coastal area that often cause erosion. At its simplest, dunes that store sand are stabilized by shal- low-rooted vegetation. People walking across the dunes break the root systems, weakening the plants and leading to their destruction. Without the vegetation, the dune is easily eroded and the sand is lost to the beach system. A public beach draws a large number of pe'ople who require parking and amenities, such as changing rooms and food supply. These requirements mandate that the shoreline must be managed and not allowed to vary greatly in its width or position. This management can range from restricting times of year when the beach is open to constructing large-scale, hard structures, including groins and breakwaters. Beach nourishment using sand from other areas is an intermediate approach that is often used. Unless large buffer distance is available, residential use creates the same situation. If the shoreline erodes, improvements on a lot, such as hous- es, become endangered. Some type of shoreline stabilization is demanded to protect homes. Because home owners usually have limited financial resources, stabilization projects taken on by individuals tend to be small. Public use includes roadways, which have public investment and are needed for public safe- ty and emergency services. Therefore, large, hea%V structures are built to protect the road. These often disrupt the beach system and lead to further erosion which leads to further construction. Commercial activities, such as motels and restaurants, make similar demands and their approach tends to be an intermediate one, between private residential uses and public facilities. Boating, with its need for vertical bulkheads and deep water next to the shore, also affects erosion. In Southold, the marinas' private moorings are in inlets where erosion is not a.major concern. However, inlets naturally shoal, close, and change position, none of which are acceptable to boaters and marina owners. Boating leads to the demand for dredging, which has been discussed 1-30 Flood-P=one Areas The danger from large storms is not limited to erosion from wave action; flooding from elevated water levels damages properties, some far inland. As discussed earlier, the maximum water level expected in the Long Island Sound shore of Southold is about 14 feet above MSL, and the 100-year flood level is about 10.7 feet. These levels are lower on the Peconic Bay side. Because of the bluffs, most of the inhabited areas of the Long Island Sound shore are above these elevations. The four exceptions are the mouth of Mattituck Inlet, Goldsmith Inlet to Kenneys Road Beach, Hashamomuck Beach, and Truman Beach. On the Peconic Bay side, much of the shoreline and inlets is subject to flooding. There are fewer areas above flood elevations than areas that are subject to flooding. With the exception of Little Hog Neck, almost all of the shoreline is Just about or slightly more than 10 feet above MSL. While most houses do not flood regularly, such areas as Fishermans Beach and Marratooka Point flood several times a year. C · SIR~'IAKY This report describes the evolution of existing coastal landforms and the specific processes that govern the continuous landform changes. Where explana- tions were necessary, the processes were presented in cause-and-effect rela- tionships -- e.g. the relationship between wind and waves and erosion of beaches. The section provides a concise frame of beach and water interactions and the physical problems that apply to Southold, as well as the reasons for problem areas. In st~mary, the primary concerns within the Southold area in- clude long-term and storm-induced beach/dune and bluff erosion, and the flood- ing and erosion of low-lying areas associated with storm events. Beaches are composed of loosely compacted sediments, usually sand or gravel. The beach profile shape depends on the incident wave energy and sedi- ment size. Beaches are dynamic; most change annually due to varying wave cli- mates. During the s,,mmer months,-relatively long-period waves of low height persist, causing the subaerial (above-water) beach to be at its maximu~ width. As winter approaches, waves become steeper and tend to move material to an offshore bar that reduces wave energy on the beach face. This offshore move- ment reduces the subaerial beach width, yet represents an equilibrium with the winter storm climate. The cycle is repetitive, as summer approaches with the 1-31 onshore movement of beach material from the offshore bar. A noteworthy feature of this cycle is the change in beach composition from season to season as the finer beach material is more readily transported, which causes a sandy summer- time beach to be primarily cobble during winter months. During storm events, especially on open coasts, this cycle is amplified as larger waves erode the beach face and carry more sediment to an offshore bar. With the attendant increased water levels, waves attack and erode dunes and bluffs, and deposit material offshore. The growing bar in turn reduces the magnitude of wave attack on the beach face, dunes, and bluffs, thus providing a natural defense system. After the storm, the normal wave climate moves materi- al onshore to the beach and re-establishes the normal seasonal profile. Prob- lems occur when eroded bluff and dune materials are not returned to their pre- storm locations, but only reach elevations of maximum wave uprush on the sub- aerial beach. During severe storms, beach material is moved beyond the point of sediment motion under normal conditions, which effectively removes the mate- rial from the nearshore coastal environment. Dune and bluff erosion occur through these processes, requiring human intervention to mitigate the losses. Glacial bluffs are a prominent feature along the Long Island Sound shore- line; understanding the processes that cause bluff recession is critical. These bluffs, which can approach 100 feet, are composed of unconsolidated sedi- ment -- principally cobbles, sand, clay, and~ on the top of the bluff, loam. In certain areas~ primarily Pettys Cove, the bluff is composed of clay alone.. Roughly 75 percent of these bluffs are vegetated (stable), while the remainder are uncovered and actively eroding (Tanski, 1980). Some bluff areas are esti- mated to erode at rates as high as 6 feet per year. Erosional sections are mostly storm related and are caused by undercutting of the bluff by waves or tidal currents. Groundwater seepage, overland runoff, vegetation density, and bluff geometry and composition are other factors that affect bluff erosion. Once bluff erosion is initiated, the bluff steepens beyond a stable value, which is subsequently followed by slope failure and marked recession. Although bluff erosion is complex and difficult to. predict, it is easily monitored and readily stabilized through engineered mea~s. These stabilization efforts, how- ever, often fail to recognize the importance of maintaining the bluffs as a component in the littoral environment. In addition, they are expensive to construct and maintain. Bluff erosion is particularly noteworthy along the Southold shorelines, where a high percentage of the total coast is fronted by glacial bluffs. 1-32 Erosion processes are different from beach and dune erosion because bluffs serve as the major reservoir of sediment along the shoreline. As beaches are inundated and move landward, bluff material is introduced to the littoral envi- ronment. This material is then transported alongshore or offshore, resulting in further erosion of the bluff. The continuous process is a natural equilib- rium in which the bluff sacrifices a volume of material to the beach to prevent further beach erosion. Unfortunately, bluff erosion (unlike dunes) is perma~ nent, which leads to efforts to stabilize bluff faces against further erosion. The flooding of low-lying areas that results from overtopping of beaches, dunes, and coastal structures occurs along the Peconic Bay shoreline. Although the water elevations can be higher on the Long Island Sound side of' Southold than on the Peconic side, more damage usually results on the Peconic side. This is caused by the low elevation of the land on the Peconic Bays. More of the Long Island Sound side is above flood elevations, except for the area imme- diately around the two inlets and Hashamomuck Beach. Flooding alone causes a significant amount of damage to coastal communities, but also results in the loss of beach material as flood waters carry large volumes of sediments to backshore areas. This problem is particularly severe on barrier beaches and islands, and represents the natural tendency for these systems to move onshore. The continued alongshore movement of sand that is dependent on wave direc- tion and height is superimposed on cross-shore movement of sand on tha beach. Gradients in this alongshore movement erode or accrete beaches. Long-term erosion up to 2 feet per year and annual accretion rates of nearly 2 feet have been estimated along the Long Island Sound shoreline in Southold (Davies et al., 1973). In general, the shoreline is erosive with sparse accretional shoreline sections. Significant problems occur when littoral material is in- tercepted by coastal structures or inlets -- e.g., at Goldsmith's and Mattituck Inlets. At Mattituck Inlet, for example, annual updrift shoreline changes reflect roughly 3 feet per year of accretion, and downdrift erosion rates ex- ceed 1 foot per year. Erosion rates of 6 to 10 feet horizontally have been reported at Goldsmiths Inlet. Downdrift erosion is a particular problem of stabilized inlets and groins and results in steep narrow beaches that are un- able to provide necessary storm protection. 1-33 CHAPTER II. INVENTORY OF SOUTHOLD BY REACH This chapter provides a reach-by-reach description of the coastal process- es and landforms. This inventory is general in nature and is intended to give some insight to the conditions. Each reach needs a detailed study to provide specific recommendations for a parcel or groups of data in an area. The inventory is summarized in seven sketches that provide an overview of existing conditions in Southold. Figure II-1 shows the reaches and major shoreline configurations. Geographic names in the narrative are presented in Figure II-2. Figures II-3 through II-5 indicate major natural considerations, including deduced littoral drift, natural features, and environmental sensitiv- ity. Results of human activities are featured in Figures II-6 and II-7. A. LONG ISLAND SOUND SIDE OF THE TOWN OF SOUTHOLD This side of the Town of Southold is exposed to the waves of Long Island Sound from 9 to more than 20 miles fetch, generating waves from up to 6 to more than 9 feet in 75 mile-per-hour, hurricane-force winds. Wind-generated waves are the primary cause of coastal erosion; certain individual areas are greatly affected by their orientation toward the waves. During the 1990's, points fac- lng northeast have been heavily eroded by four major storms: Hurricane Bob, the Halloween storm, and the storms of December 12, 1993, and December 24, 1994. Shorelines with a more northerly exposure have not been as affected in the 1990's. Bluff composition and height are also very important factors in calculating erosion levels. The silty-clayey sediments in Pettys Bight have been heavily eroded while the rocky points, such as Horton Point, have resisted erosion forces more successfully. High bluffs, such as those east of Mattituck Inlet, have supplied large volumes of sand to the shoreline. Low bluffs or dunes do not provide the necessary volume of sand, and the downdrift shorelines are usually eroding. E. REACH 1: TOWN LINE TO DUCK POND POINT The coastal erosion processes in Reach 1 are dominated by the jetties at Mattituck Inlet (see Figure II-8), which block the normal littoral drift. Be- cause of this blockage, the shoreline has changed over a period of time. The II-1 ISLAND NEW SUFFOLK [] Reach Number ROBINS ISLAND LITTLE PECONIC BAY ' · NOR111 SEA LONG ISLAND SOUND ORIENT [] I~l .~R~OR PLUM ISLAND i~,~...~ SHELTER / ~ ~AND NORTH HAVEN o 2 MILES SCALE Figure I1-1 Southold Reaches SCALE FISHERS ISLAND DUCK POND L°NG ISLAND SOUND ~RY m HORTON ~ HARBOR SHELTER ISLAND PLUM ISLAND [] Reach Number NECK  ~Oe~U~T~ ~oerr LITTLE PECONIC CREW( BAY DOWN~ CREEK -J ROBINS /' GREAT CREEK NOYACK SAG HARBOR 0 2 MILES SCALE Figure 11-2 Geographic Names 7.95 KALE :iS ISLAND £ONG ISLAND SOUND PLUM ISLAND ORIENT ~HARBOR ISLAND F-LANDERS BAY UA.,,UCK LITTLE ~ BAY H~EN ROBINS // NOYACK GR~T ~'X · NOR~ S~ o 2 MILES SCALE PECONIC [] Reach Number ~ Deduced direction Figure 11-3 Deduced Direction of Littoral Drift 7.95 MATTITUCK NEW SUFFOLK Lr/TL h~G NECK  ROBINS ISLAND G REA T PECONIC BAY LITTLE PECONIC BAY NORTH SEA [] Reach Number ............. High bluffs ...................... Low bluffs ~ Flood prone LONG ISLAND SOUND ORIENT PLUM ISLAND SHELTER ISLAND NOYACK SAG HARBOR SPRINGS 0 2 MILES SCALE Figure 11-4 Natural Shoreline Features LONG ISLAND SOUND ORIENT BAY SHELTER ISLAND HOG NECK PLUM ISLAND MATTITUCK GREAT FLANDERS BAY PECONIC  BAY [] Reach Number $ NEW SUFFOLK L~m HOG NECK ROBINS ISLAND Ma~h · ' Bird Nesting LITTLE PECONIC BAY PO~4T NOYACK · NORTH SEA SAG HARBOR SPRINGS 0 2 MILES SCALE Figure 11-5 Environmental Sensitivity SCALE MAI-rlTUCK -'LANDERS [] Reach Number ]=own of Sou,thot,d LONG ISLAND SOUND ORIENT ] HARBOR BAy LITTLE HOG NE~ PLUM ISLAND PECONIC ~ ~e;~om NEW SUFFOLK Lrrn~ BAY I~ IS~ND NOYACK G REA T PECONIC SHELTER ISLAND ~AY · NORTH SEA SAG HARBOR SPRINGS Heavily structural Medium structural Light or non-structural 0 2 MILES SCALE Figure 11-6 Structural Shoreline Protection 7-95 LONG ~LAND SOUND ORIENT SHELTER ISLAND PLUM ISLAND FLANDERS BAY [] Reach Number · ,-- 5mall lots ~ NECK LITTLE t PECONIC .m,o~r NEW SUFFOLK ~o~c~n3t~ BAY I ~ ROBINS ~1 iS~ND / NOYACK ......... P~blic uses ~ Commercial u~es SAG HARBOR SPRINGS 0 2 MILES SCALE N Figure 11-7 Land Use N ..." '..: ;~ ss~ ~ ...." ~" "~,,,~ ...."9 8 9 lO 8, 9 ? *3 ..... .'" ,.'" .2'~.~,~,~,~.:. ,o .."~ , ..." / ..-". ~ · ,.. ~,?~,.~ ~ ~.~'.. ..... .. ..... / ...' ~ .... ....... ; ,~,:~ / ~~ ~ ~ .....~~ .....~~~..-~ -~ . . SOUNDINGS - feet below Mean Low Water Source: National Oceanic and Atmospheric Administralion CONTOUR - feet above Mean High Water Figure 11-8 Mattituck Inlet I I I I I I I I I I I I I I I I I I I predominate drift direction is from west to east, but waves from large storms often come from the northeast and move the sand from the east toward the west. Reach 1 west of Mattituck Inlet appears to have stabilized due to the jetties. The area next to the west jetty has filled with sand, which is migrating around the end of the jetty into the channel. The shoreline from the town line to the west jetty is smooth. The east side of Mattituck Inlet does not appear to have stabilized. Just east of the inlet, the beach is eroding and the low dunes have not been able to supply sufficient sand to replenish the volume blocked by the jetties. The bl6ff, which rises to between 80 to 100 feet at Oregon Hills, has been attacked at the toe and has slumped in a number of locations. These slumps have been supplying sand along this reach. Because of erosion, the foundations of a hotel constructed on the beach at the end of Duck Pond Road have been under- mined. C. REACH 2: DUCK POND POINT TO HORTON POINT The bluff is 40 to 60 feet high east of Duck Pond Point for about 7,500 feet. About 2,000 feet of various bulkheads have been built along the stretch. The bluff then drops to about 20 to 40 feet high, and ends at Goldsmith Inlet. Jetties were built at Goldsmith Inlet in the 1960's as part of a New York State plan for a marina in the park, but the marina was never built and the inlet is not navigable. It would probably close except that the Town dredges it yearly for the sand. The shoreline west of the jetties has come back into equilibrium with the coastal dynamics. The shoreline to the east, however, does not re- ceive sufficient sand and is eroding, despite the construction of several groins and bulkheads. The problem is most severe at the easternmost beaches, where oversized groins disrupt the littoral drift and may cause the sand to be lost offshore. The low dunes do not store sufficient sand to compensate for the erosion. The easternmost stretch has not experienced much erosion; accord- ing to long-time residents, it has actually accreted sand. Horton Point pro- trudes far enough into Long Island Sound to provide protection from most storms. The angle of Horton Point makes the waves diffract around it, weaken- ing their energy before they break'on the shoreline. II-2 I I I I I I I I I I I I I I I I I I I D. REACH 3: HORTON POINT TO ROCKY POINT The conditions along Reach 3 are variable. While portions of the shore- line are stable, others remain unstable, causing damage to several houses. At Horton Point, the bluff is high, and the shoreline has smoothed out over the past 60 years. Although some erosion has occurred, there has been no property damage. After about 4,500 feet, there are protective shoreline structures even though the high bluff continues for about another 3,000 feet. Various types of structure and building materials have been used in this 3,000-foot length of shoreline west of Towa Beach, but they have either been ineffectual or in- creased erosion. The Town Beach has been eroding; to the east, the shoreline has experienced severe erosion. The December 1994 storm led to the condemna- tion of two houses, and County Road 48 is threatened in several areas. The erosion may have been aggravated by the groin on the west. About 7,000 feet east of Town Beach, the bluffs reemerge and the shoreline is generally stable through Inlet Point. Because Inlet Pond sits between the bluffs and Long Island Sound, exceptionally high tides can result in water overwashing the beach at Inlet Point. From Horton Point to Inlet Point, the predominate drift direction is from west to east. The bluffs are very steep from Inlet Point to Rocky Point, and the beaches are generally stable ~nd very rocky. E. REACH 4: ROClUf POINT TO ORIENT POINT The first 4,000 feet of Reach 4 extends almost due east-west and has a steep bluff. This very rocky area has been fairly stable. The bluffs then give way to a smooth embayment that includes Truman Beach; East Marion Orient Park -- an area that has eroded over the years -- is to the east. From Terry Point to Mulford Point, the shoreline is rocky an~ backed by a steep bluff. The area from Mulford Point to Orient Point, known as Pettys Bight, has recently experienced severe erosion. Although no erosion problems were reported for 30 to 40 years, the five major storms in the 1990's have caused large-scale ero- sion. The area around Orient Point also narrowed during these storms. F. KEACH 5: ORIENT POINT TO YOUNGS POINT (GREENPORT) Like all of the Bay side shoreline, Reach 5 has a wide range of erosion potential and causes. Orient Point is fully open to Gardiners Bay and experi- ences waves similar to those on the Long Island Sound shoreline. The beach is II-3 all stone and cobbles, with three rock groins between the Orient Point ferry slips and Orient Point. Orient and Long Beaches, west of the ferries, are also fully exposed to Gardiners Bay. They form a long spit extending to the west- southwest. The roadway was breached during the December 14, 1994 storm, and now lies in pieces under water. The roadway has since been rebuilt north of its old location. The beach is a mixture of rock and sand, except at the pub- lic bathing areas, where it is all sand. There are about 10 groins in various state of repair along the beach, where the predominate direction of littoral drift is from east to west. Long Beach Point is reported to change its orien- tation from season to season. The spit protects Long Beach Bay, which is lined with intertidal marshes. Long Beach Bay is not exposed to wave-generated ero- sion, but some tidal currents have affected the shoreline. A channel was dredged and then lined with bricks to give access around Peters Neck and Browns Point. Although it has changed the circulation pattern, it does not seem to have caused erosion. Orient Harbor is an open bay, protected by Long Beach on the southeast and Shelter Island on the southwest from the waves of Gardiners Bay. Between the end of King Street and Peters Neck Point, there are almost 20 groins along the beach, where the predominate direction of littoral drift is to the south. The predominate drift direction changes to the north near King Street. A number of groins, bulkheads, and the Orient Yacht Club pier line the shoreline up to the tidal marshes at the head of Orient Bay; the shoreline is then armored with stone to protect the road. The land is less than 1,000 feet wide in this area. At Dam Pond, there are only two thin strands of land, Truman Beach and Main Road. The shoreline from Dam Pond to Spring Pond is lined with more than 20 groins and many bulkheads; the predominate direction of littoral drift is from the northeast to the southwest· The mouth of Spring Pond is kept open by a pair of jetties. The shoreline from Gull Pond to Cleaves Point contains many erosion-control structures. The Gull Pond Inlet was first dredged in 1959, when 177,200 cubic yards of sand were removed. It is dredged about every 10 years; about 20,000 to 25,000 cubic yards of sand are removed. It is currently kept open by jetties. Overall, Orient Harbor is heavily protected by struc- tures. Although Orient Harbor is only a little wider than 2 miles, wave action is sufficient to be the main cause of erosion and beach movement. Tidal cur- rents are important in shaping the shoreline around Peters Neck and Long Beach Points. II -4 The stretch of coast from Cleaves Point past Gull Pond to Youngs Point is well protscted by Shelter Island and does not experience high wave action. However, the shoreline is heavily protected with structures of various types. The direction of sand movement seems to be from east to west, but can be highly variable. At the mouth of Gull Inlet, tidal currents predominate in the forma- tion of shoals, both inside and just outside the inlet. These shoals act as sink for the sand, removing it from the beach system. REACH 6: FANNING POINT TO FOUNDERS LANDING Pipes Cove spans Fanning Point to Conkling Point. Tucked behind Shelter Island, the cove is about 5,000 feet wide. The two sides of the cove are pro- tected by structures, and the head is the mouth of two creeks, Moores Drain and drainage for Arshamonaque. There are tidal wetlands at the mouth of the creek and freshwater wetlands farther inland. The beaches have been fairly stable, overwashing during storms but building back fairly rapidly. The high developed land along the east side of Conkling Point is protected by bulkheads for its whole length, and almost 20 groins have been built along this area. Because of the bulkheads and limited fetch to build waves, movement of sand is predomi- nantly controlled by currents, although storms move sand depending on the wind direction. The general direction of drift is north on the north half of the shoreline and south on the south half. Conkling Point itself has been accret- lng sand and has expanded to the southwest. The west side of Conkling Point, facing Brick Cove, is also heavily bulk- headed with more than 15 groins. At the northwest end, the shoreline turns toward an east-west orientation. There are dredged basins near the turn, which were initially dredged in 1959 (163,900 cubic yards) and redredged in 1963 (129,200 cubic yards). They are protected by stone and metal jetties. Just west of these basins, Mill Creek -- the entrance to Hashamomuck Pond and cur- rently the entrance to the Port of Egypt marina -- has been dredged regularly since 1963. The old entrance on the west side of marina at Budds Pond has been closed off, and the offshore bar in front of Port of Egypt is maintained by dredging. This area is open to waves from the south across Southold Bay, and the fetch is about 10,000 feet, allowing for waves as high as about 3 to 4 feet. Storm waves and tidal currents at the mouth of the inlets have led to erosion, but structures and dredging have been the major forces in shaping the current shoreline. 11-5 At Budds Pond, there shoreline has a north-south orientation. The predom- inate direction of littoral drift is to the south, and the shore is open to waves from the east. These waves can reach 3 to 4 feet in height. The shore- line is heavily bulkheaded with almost 20 groins, and the mouth to Biexedon is protected by two large jetties. H. PEACH 7: FOI]B'DERS LANDING TO INDIAN NECK The confluence of Town and Jockey Creeks at Harpers Point has complex tidal currents and is exposed to waves from the east. The mouth of the creeks has been dredged for many years, further complicating the situation. A shoal has protected the mouth for many years with the channel on the east side of the shoal. The shoal is connected to the shore line, just north of the mouth of Goose Creek, which is part of the tidal mouth complex. The east end of the shoal was bulkheaded to prevent sand from depositing in the creek and to hold the shoal in place. The bulkhead was destroyed in the December 1992 storm and has not been replaced. The shoal has eroded, exposing Harpers Point to wave action. The lee side of the shoal is next to the dredged channel into Jockey Creek, and when waves overtop the shoal, sand is deposited in the channel. The shape of the shoreline is controlled to a large degree by dredging and tidal currents, but east winds, which cause westward traveling waves, contribute to erosion of the area. The north shore of Great Hog Neck is open to waves from a north and north- east storm. The shoreline is heavily bulkheaded. Small boat basins have dredged into Great Hog Neck. The predominant direction of littoral drift ap- pears to be to the east. According to baymen, the tidal currents run east during both the flood and ebb. This could be caused by a tidal gyre setting up in Southold Bay. The tidal currents appear to be causing the elongation of Paradise Point. Between Paradise and Cedar Beach Points, Cedar Beach is open to waves across Shelter Island Sound. The shoreline is bulkheaded and has about 20 groins protecting it. The shoreline appears to be eroding due to wave action. However, some accretion is occurring around Cedar Beach Point, and the tidal currents at Cedar Beach Creek form shoals around its mouth. The south shore of Great Hog Neck is open to waves from the south across Little Peconic Bay, a distance of 30,000 feet. Although winds from the south typically blow in the sualmer and are usually low speed, the back side of a storm can cause high winds II-6 I I I I I I I I I I I I I I I I I I I from the south. The shoreline is bulkheaded and has more than 40 groins, espe- cially towards the east end of this stretch. Corey Creek ends the south side of Great Hog Neck, and Richmond Creek is at the head of Hog Neck Bay. These form the apex of the bay, which is open to waves traveling towards the northwest. Similar to the waves that affect Cedar Beach, these are normally small, but the backside of storms can generate ero- sion-causing waves. Corey Creek was first dredged in 1963-1964 (345,600 cubic yards) and has been maintenance dredged regularly since. Richmond Creek was first dredged in 1959 (123,000 cubic yards) and is regularly dredged. The dredged materials have been used for various purposes and placed in different locations. In January 1995, about 20,000 cubic yards was dredged and mounded in the beach at Emerson Park. The dredged material was bulldozed into sur- rounding vegetated areas to smooth it out. The bars at the mouths of the creeks overwash during storms, but normally rebuild quickly. The tidal cur- rents form shoals inside and outside of the mouths of the creeks. The dredging and tidal currents are the major forcss shaping the shoreline. I. R,~,CH 8: INDIAN NECK TO DOWNS CREEK The shoreline curves around Indian Neck to a north/south orientation along Little Hog Neck. This curve is interrupted by one inlet at Little Creek that is dredged yearly. The shoreline from the public beach south to Nassau Point is bulkheaded along its whole length with many groins. This shoreline is backed by a very steep bluff that quickly rises to more than 50 feet. This bluff has eroded in places from groundwater seeps that are not associated with coastal erosion. The fetch across Hog Neck Bay to Jeesup Neck is about 20,000 feet, and the waves come directly from the east. The direction of littoral drift is very sensitive to wave direction and can reverse many times during a year. According to baymen, the tidal current along this shoreline always sets towards the south. Nassau Point seems to be elongating in response to littoral .drift and the tidal current. The west side of Little Hog Neck is punctuated by two natural inlets for Hog Creek and one dredged basin. The shore is open to waves from the south- west, but Robins Island provides shelter. The coast is protected by a number of bulkheads and groins. The shoreline is not as steep and high as the east side. South of the Hog Creek inlets, the land rises to about 20 feet. From the inlets north, the land is low lying. Meadow Beach, which is a Nature II-7 Conservancy preserve, is a small blunt spit formed by placement of dredged materials. The small boat channel between Meadow Beach and Little Hog Neck was dredged, but has generally maintained its depth without additional dredging. According to local residents, Meadow Beach has not eroded for at least the past thirty years. North of Meadow Beach spit, an inlet serves as the mouth of three creeks, East Creek, Mud Creek, and Baywater/Broadwater Coves. This inlet was first dredged in 1966 (434,000 cubic yards) and now is maintenance dredged every one to two years. The beach on the west side lengthens to the east and into the channel, requiring dredging. The channel used to run in front of Fishermans Beach, but now runs straight out from the inlet. A large shoal, not attached to the shoreline, has formed on the west side of the channel, and a smaller shoal, attached to Fishermans Beach, is forming. The beaches on either side of the inlet regularly overwash and flood the houses. The beaches have eroded back about 20 feet in the past 20 years. The shoreline of Fleets Neck is ex- posed to waves traveling west/northwest from little Peconic Bay. It is bulk- headed, and the beach is primarily fashioned from placement of dredged mater- ials. The bluffs behind the beach rise to about 50 feet. Wickham Creek was first dredged in 1966 (48,300 cubic yards) and is now dredged regularly. Between wickham Creek and Schoolhouse Creek, the shoreline is partially bulkheaded with heavier bulkheading towards Wickham Greek. This shoreline is open to waves coming from the east across Cutchoque Harbor. Schoolhouse Creek is dredged occasionally. Sand accretes in the vicinity of New Suffolk Marina and the Robbins Island ferry slip, which is dredged yearly. The groin for the New Suffolk point was recently rebuilt, and the New York State Department of Environmental Conservation has installed a sand trapping system. The Town Beach is open to waves from the south coming across Great Peconic Bay, a distance of about 37,000 feet. According to local residents, however, the beach has not eroded, but has been stable. The shoreline is backed by a low ~luff. Based on the spit at Kimogener Point, littoral drift is general from %asr to west. West Greek was dredged in 1966 (92,500 cubic yards) and is dredged regularly. At least since the 1950's, the shoreline from West Creek to Do~zns Creek has been eroding except when dredged materials have been placed on it. Several deteriorating groins are located along this beach. 11-8 I I I I I I I I I I I I I I I I I I I J. PaT..ACH 9: DO~,,~,IS CKEEK TO TI'Ill TOI.~I LINg The reach is fully open to the Great Peconic Bay, and the shoreline is shaped by two large embayments or bights (gentle concave curve between two points). The first bight is between Kimogener and Marratooka Points, distance of about 6,000 feet, and the second between Marratooka and Brushs Points, a distance of about 16,000 feet. Based on an open water fetch of 32,500 feet across Great Peconic Bay, a hurricane force wind (75 miles per hour) can generate waves up to about 4 to 5 feet high. This wave height is somewhat limited because the bay is only 20 to 25 feet deep. The shallow water retards wave growth. Downs Creek is not regularly dredged and shoals form at its mouth. Place- ment of dredged materials from Halls and Deep Hole Creeks provide sand, that is then shifted by the wave and current action. Since,the 1950's, six groins have been built between Downs and Halls Creeks. Bulkheading started in the 1920's, and the shoreline is now heavily bulkheaded. Halls Creek was first privately dredged in the 1920's. In 1965, deep channels were dredged from Halls and Deep Hole Creeks (243,000 cubic yards) to a joint channel about M-mile offshore. The channels are maintenance dredged regularly with the sand placed on the beaches. The spit in front of Deep Hole Creek is accreting towards the east, indicating a west to east general littoral drift. Between the two creeks, two deteriorated groins do not prevent erosion of the shoreline. The shoreline between Deep Hole and James Creeks is heavily bulkheaded with many groins. The predominate direction of the littoral drift is west to east. The mouth of James Creek is protected by jetties, with the west jetty built in the 1940's. When the channel was first dredged in the 1940's, a layer of cohesive peat and clay acted as a jetty on the east side of the chan- nel to a certain extent. This layer has been eroded, and a shoal formed in the channel, about 300 feet into the creek. During the 1950's when no eastern jetty existed, the eastern shore eroded back about 1,000 feet. In 1964 two Jetties were built on the east side to stabilize the channel and the shoreline. As a result, the western shoreline extends about 1,000 feet bayward, more than the eastern shoreline at the mouth of 3ames Creek. The channel is dredged about every three years, and the dredged material is normally placed on the eastern shoreline. The jetty on the west is usually filled with sand. Between James and Brushs Creeks,. the shoreline is heavily bulkheaded with about 70 groins. Brushs Creek was first dredged in 1966 (86,400 cubic yards) and is II-9 maintenance dredged regularly. The dredged material is placed on either side of the inlet depending on the degree of erosion. The shoreline between Brushs Creek and the town line is heavily bulkheaded and has about l0 groins. K. PEACH 10: FISHERS ISLAND Because of its location, land use patterns, and geology, erosion at Fish- ers Island is very different from the rest of Southold. The island is mostly elevated and rocky. Very few erosion protective structures have been built along the shoreline. The south side of the island is exposed to Block Island Sound, although the narrow opening at the Race acts as a constriction on the wave energy striking the island. The cliffs have been eroded and only the largest stones remain in place. The beaches are made up of cobbles approxi- mately 3 inches in size. This situation has minimized ongoing erosion. The houses have been built on the cliffs and set back from the edges. Therefore, erosion does not seem to cause problems on the south side of the island. The north side of Fishers Island faces Connecticut, approximately 2M miles across Fishers Island Sound. The north side of Fishers Island experiences much lower wave energy. Most of the north side is also elevated and the houses are not endangered by erosion. However, several houses in West Harbor have been built in a low-lying area, End the home owners have built groins to protect the houses. These structures have had some success. II-10 CHAPTER III. COI~40N MANAGEI~NT UNITS A. INTRODUCTION Although the Town of Southold's shoreline is highly variable and various coastal processings are shaping different glacial landforms, certain commonal- ities emerge. The natural common elements relate to wave exposure, proximity to tidal inlets, bluff height and stability, and flooding. The human elements include land use, lot size and shape, marine-related activity supported in the area, and already constructed erosion measures. When these factors are com- bined, they form common management units where certain coastal processes are dominant, and certain erosion protection policies are most applicable. Figure III-1 presents the common management units. On the Peconic Bay shoreline, these units overlap, and more policies need to be considered. On both shore- lines, particularly on the Peconic Bay side of Southold, the boundaries are not definitive, and further study is required to precisely characterize the unit and define its boundaries. B. LONG ISLAND SOUND COAST Three common management units make up the Long Island Sound coast of Southold; these are: areas directly affected by the two jetties, areas of Iow bluffs and dunes, and areas of high bluffs. These features are shown in Figure II-3 and II-4. JeC~yAreas The jetties at Mattituck and Goldsmiths Inlets dominate the coastal pro- cesses and responses in the area. Although it does not affect coastal pro- cesses, the fact that Mattituck Inlet is navigable is an important policy con- sideration. Mattituck Inlet supports a strong, thriving maritime community that is dependent on navigating the inlet. Goldsmiths Inlet is not navigable and does not support any type of human activity. From field observations and map studies, the direct effects of Mattituck Inlet are felt about 1 mile to the west and about M of a mile to the east. On the west, sand has been trapped by the jetty, and the shoreline has built out. The west jetty is close to com- III-1 SCALE ~'~.~ ~'/~! ~ ~.~ ISLAND LONG ISLAND SOUND ORIENT HARBOR SHELTER ISLAND PLUM ISLAND HOG NECk( MATTITUCK GREAT FLANDERS my PECONIC  BAY LITTLE % PECONIC ~ NEW SUFFOLK T~ BAY ]) I t ROBINS / ~'J NOYACKe Long Island So. nd Peconic Bay ~.~ Jetty Areas "'"'""""' High Bluff "'"'"""""""" LOW Bluff Creek Mouth ........... Exposed Area ~ Protected Area ............ Flood Prone SAG HARBOR SPRINGS o 2 MILES SCALE Fi~,ure III- 1 Common Management Units I I I I I I I I I I I I I I I I I I I pletely full, and sand is being lost, either offshore or into the channel. As long as the jetty is functioning, the west side of Mattituck Inlet will be protected from erosion. However, sand that would help erosion on the east side of the jetty is being lost into the channel and offshore. The east side of the jetty has experienced severe erosion and loss of dunes. As discussed in Chapter I, these dunes have in the past acted as sand "banks;" during severe storms, sand is withdrawn and used to help the beach recover. However, the dunes are now much reduced in size and far landward of the beach. They may no longer act as "banks." The two jetties and the channel intercept the flow of littoral drift and hold the sand on the west side of the inlet. From map comparisons, it appears that the eastern shoreline has recov- ered to some degree, but not completely. The major factor limiting the down- drift erosion is the presence of Oregon Hills, which acts as a large sand source feeding the beaches further downdrift. Maps do not indicate a large degree of erosion of Oregon Hills. The beach between the east jetty and Oregon Hills has eroded because of the lack of sand. Some sand has been added to the beach, both by natural by- passing and some human activity. Maps show that the beach has responded by flattening its slope. This means that the added sand has not moved the normal high water line further seaward, but that the sand is being deposited just offshore, creating a shallow beach. The sand is slowly filling the area behind the jetty. This process will not rebuild the dunes until the triangle of sand in the shadow of the jetty is exposed to the air where the wind can blow the sand landward. At the current rate, dunes will not start re-forming for many years or decades. The jetty at Goldsmiths Inlet does not have an updrift effect as large as at Mattituck, primarily because it is shorter. The updrift influence is about W mile. The downdrift effects have been more apparent because of the low ele- vation of the land. Unlike the high bluffs of Oregon Hills, Horton Lane Beach is low lying with a bluff located well inland of the water line. The effects of Goldsmiths Inlet jetties arp felt for more than 1M miles downdrift. Horton Lane Beach regularly erodes an~ requires replenishment. Erosion protection policies are discussed in the next chapter, but the major factor in applying them in the vicinity of the jetties is the effect on the downdrift side, which is threatened by erosion. Methods should be applied wherever possible to have sand by-pass the jetties. This by-passing has the double advantage of preventing sand from being lost offshore and supplMing it immediately to an area prone to erosion. III-2 immediately to an area prone to erosion. Areas of Low Bluffs and Dunes Areas of low bluffs and dunes include Horton Lane Beach (discussed above), Hashamomuck Beach, and Pettys Bight. These areas are characterized by the lack of high bluffs next to the shore. High bluffs on the Long Island shore of Southold tend to be more than 40 feet high, while low bluffs are typically less than 20 feet high. The bluffs in these areas can also be inland or non-exis- tent. Some dunes may be found behind the beach. In Pettys Bight, the bluff is generally less than 20 feet high. To a certain degree, these areas also coin- cide with small building lots. These lots tend to be narrow and deep, allowing houses to be set back from erosion danger. The dunes around the inlets and near Hashamomuck Beach are the only place on Southold's Long Island Sound coast where flooding occurs landward of the shoreline. Excluding the jetties at the two inlets, few shore protection structures are found on Southold's Long Island Sound coast, but they are found along these areas. Each of the structures has been built to protect a single lot or a small area, and no overall plan has been developed. Along the areas of low bluffs and dunes, structures should only be allowed when a house on such public properties as beaches and roads is in danger, and no other alternative will save the house. One alternative to be considered entails moving the house. The policy recommendations in the next chapter for set backs and native seaside vegetative plantings are especially applicable in these areas. Areas o~ High Bluffs High bluffs constitute much of the Southold's Long Island Sound coast. The bluffs are from 40 feet to nearly 100 feet high and consist of unconsol- idated sediment. The sediment ranges from sand and gravel to huge boulders. These bluffs are the source of much of the sand and gravel that form southold's beaches. Therefore, they ~re very important in slowing the erosion of the shoreline. Few erosion protection structures are currently found in the areas of high bluffs. The lack of structures has allowed the shoreline to erode very slowly, and natural headlands, such as Horton Point, to emerge. If hard structures are built in these areas, this dynamic would change. The hard structures would try III-3 I I I I I I I ! I i I I I I I I I i i an overall increase in the rate of erosion as the shoreline tries to come into equilibrium. A problem on bluffs is the presence of clay lenses. The only area with large clay lenses is Pettys Bight (a low bluff area), but some are also found in the high bluffs. Clay layers can cause erosion of the bluffs. The clay tends to be impervious to water, and the water migrates along its upper sur- face. If a large source of water, such as a septic system for a restaurant, is located above the clay, the water will flow out to the bluffs. This creates a wet area where internal pressure from the water can be greater than the fric- tion holding the sediment together. When this happens, the sediment slips and the bluff slumps. C. PECONIC BAY SIDE OF SOUTHOLD The coastal dynamics of the Peconic Bay side of Southold are more varied than the Long Island Sound side. As described more fully in Chapter II, many inlets, marshes, varying wave exposures, and opposing tidal currents character- ize the shoreline. Generally four common management units emerge: creek mouths; wave exposed shorelines; wave protected shorelines; and flood prone areas. Certain locations may have two of these characteristics, and therefore policy decisions will involve weighing the management objectives. An example is Fishermans Beach, which floods regularly and is at the outlet of three creeks. Creek Houths Creek mouths act as a funnel for tidal currents, speeding the water flow and carrying sediment in and out of the creeks. When the current reaches the wider areas inside and outside of the mouth, the current slows dow~ and some of the sediment is deposited. These deposits form the shoals around the creek. Almost all of the creeks are used for navigation, and the shoals need to be dredged to provide sufficient navigation depth. The dredging and use of the dredged materials is the key management objective in these areas. This dredged sand is a valuable resources that needs to be used wisely to prevent erosion and to build beaches. The most beneficial use of the sand varies from inlet to inlet, and will vary at the same inlet in different years. The storm direction and its attendant waves change; one storm moving sand to the east, and the next 111-4 moving the sand to the west. Each decision concerning where to place the sand will depend on the storm pattern that most recently affected the inlet. Within this management unit, the length of jetties to stabilize the inlets is important. At James Creek, the west jetty is 200 feet long while the east jetty is 50 feet long. This length has stabilized an offset inlet with the west side seaward of the east side. The east side erodes and requires periodic beach fill while the west side has trapped all the sand that it can hold. When jetties are proposed, careful thought about the relative length and placement is required. F, xposed Shores The Peconic Bay Side of Southold has several shores exposed to waves com- ing across Great Peconic Bay, Hog Neck Bay, and Gardiners Bay. For the most part, these shorelines have been heavily protected with bulkheads and groins (see Figure II-6). The low lying nature of some of the shoreline and easily eroded sediment in the bluffs led to the early use of erosion protection struc- tures. Because so much of these shores have been protected by erosion-control structures, the few remaining unprotected lots are eroding. Therefore, it would be very difficult to refuse permission to one homeowner to protect the property when all the surrounding houses have bulkheads. However, standard designs can be developed that will minimize effects on updrift and downdrift properties. Groins are particularly common and should be thought of as groin fields, not as individual groins. As an example, an eight-groin field had been installed and worked well. When a ninth groin -- longer and 2 feet higher than the existing groins -- was installed, erosion ensued and the groin field no longer functioned properly. W'hen a groin field is designed as a whole, specif- ic lengths, heights, angles, and spacing can be developed so that all of the groins act as a unit and provide the most benefit to all of the homeowners. Protected Shores Protected shores include Hallock Bay, Pipes Cove, Conkling Point, and parts of Sou~hold Bay and Cutchoque Harbor. These areas are also heavily pro- tected with bulkheads and some groins. Flooding has led to most of the bulk- head construction so that a house can be raised above the flood plain. In these areas, the granting of permits should not be automatic, especially for III-5 I I I ! I I I I I i ! I I I I I I I I tected with bulkheads and some groins. Flooding has led to most of the bulk- head construction so that a house can be raised above the flood plain. In these areas, the granting of permits should not be automatic, especially for groins. Wave action is not the major cause of erosion, but groins can exacer- bate the effects of waves. The problem that the structure would solve should be clearly defined and the use of non-structural measures analyzed. In many cases, beach filling can solve or at least ameliorate the problem. To accom- plish this, cooperation among neighbors and with DEC will be required. The people most affected would have to jointly allow the beach filling across all of their properties. If one neighbor objected and did not allow new sand to be placed on their property, the beach filling may not function as well as it could. In addition, DEC will need to allow the beach filling project. Long- term coordination among the Town, DEC, and Suffolk County is required so that dredged material is reintroduced into the littoral system and used to ameli- orate erosion problems. Flood-Frone Areas Many areas on the Peconic Bay side of Southold are flood-prone. The prob- lem with flooding is not the flooding itself, which is an inconvenience, but the damage to houses and property. The traditional method of preventing dam- age has been to protect the property and houses with bulkheads. This approach raises the ground out of the floodplain. Another method used in other areas consists of building the house on piles with the floor above the floodplain. When a flood occurs, the water goes under the house but does not damage it. Placing houses on piles raises other issues -- such as building height and appearances -- that need to be addressed. Installing breakaway foundation walls and limiting the number of stories in a house could satisfy many of the other concerns. While this method would not work for existing houses already protected by bulkheads, it would work for new houses. III-6 i I i I I i I I I i I I I I ! I I ! I CHAPTER IV. PROPOSED EROSION HANAGEHENT POLICIES A. PREAHBLE Southold's shoreline is more than 26 linear miles long, and when the em- bayments, inlets, and spits are included, the coast stretches to more than 163 miles. This diverse shoreline attracts a wide variety of human and natural activities. Almost 1,000 acres of protected tidal wetlands and more than 1,400 acres of shellfish beds are encompassed in this coastal area. Miles of beaches and shore parkland attract visitors and residents. Homes and summer houses line the shore. Marine businesses, including fishing, shell fishing, transpor- tation, recreational boating, and construction, are vital to the economic well being of Southold and its residents. To stabilize and protect these shores for human uses, myriad structures have been built over a period spanning many years. These include groins, jet- ties, bulkheads, and revetments. To improve navigation for both business and pleasure, channels have been dredged through the inlets, and the dredged mate- rials used to make new land or added to beaches. Each construction project took place with a view to achieving its own goals, whether protection of one landowner's beach or the creation of a navigable channel for a particular mari- na. These projects were often undertaken without regard to the overall effects on the coastal processes. The dredging and building of jetties at Mattituck Inlet have'served the marina businesses and boaters well, but have led to loss of beach east of the inlet. In other instances, shore protection structures have protected one property owner, but have damaged neighbors' properties. One of the main purposes of the coastal erosion policies is to ensure that the con- sequences of building an erosion control facility are understood before the structure is constructed. Erosion control structures often contribute to erosion both on- and off- site due to poor design and siting. Increased erosion, aesthetic impairments, loss of public recreational resources, loss of habitats, and water quality degradation can result from poorly placed or designed erosion control struc- tures. The cumulative impact of a number of individual structures can be even more damaging. Therefore, the purpose and function of erosion control struc- tures must be defined, and the consequences and potential impacts, both on- and IV- 1 off-site, need to be analyzed, before permission is granted for building a structure. As discussed earlier, the number and type of erosion control structures differ greatly between the Long Island Sound and the Peconic Bay shores~ On the Long Island Sound shore, few structures have been built and bluffs back almost all of its length, preventing flooding. The Peconic Bay coast has been hardened by many structures, and long lengths of it are low in elevation and prone to flooding. Therefore, proposals for erosion control structures on these two shores of Southold need to be evaluated separately. The Long Island Sound shoreline generally has few structures and the houses are well above flooding elevation. Hard engineering solutions should be minimized whenever feasible, and where erosion has recently become a problem, such as Pettys Bight, a soft solution should be encouraged. The soft solutions include setbacks from the top of bluff, relocation of existing structures, setbacks from the high water line, natural vegetative buffer, and beach resto- ration. However, in certain situations, combined hard and soft solutions may be required where houses or public properties are in imminent danger. In areas of high public use, such as Horton Lane Beach, beach filling should be used to maintain the recreation values. If erosion threatens property downdrift of the two sets of jetties, sand bypassing or off-shore mining of sand should be con- sidered. With the existing heavy construction along the Peconic Bay shore, rebuild- ing of existing structures and building of new structures will be required into the foreseeable future. Unprotected properties could erode and be subjected to damaging floods. However, permits should not be granted automatically. Before granting a permit, sound engineering analysis of the effects of the individual structure within the surrounding structures, such as whole groin fields, is necessary. Soft solutions, such as the use of dredged materials for beach fill, should be the preferred approach and always included as an alternative. The soft solutions' inability to achieve the structure goals must be demon- strated before granting permission for the structure. Very often, a combined solution will work best. Installation of a carefully d~signed groin field using dredged materials to fill between the groins will probably provide a very satisfactory solution that functions well for a number of years. For both shores of Southold, whole reach or length of similar processes' analyses should be required. Consideration must go beyond a single structure or a single piece of property, and the effect on updrift and downdrift on prop- IV-2 I i I I I I I I I I I I I I I I I I I erties should be evaluated. The Town will be undertaking reach studies as a fellow-up to this study, with the area around Goldemiths Inlet as the first study. Because these studies cover multiple pieces of property~ the burden of. the study cannot fall onto an individual property owner; it is the responsibil- ity of the Town and the Board of Trustees. As discussed in Chapter V, removing and rebuilding whole groin fields should be considered. This approach would go beyond ameliorating a single person~s problem~ Further, by considering whole groin fields at a time, an entire community's problem would be addressed. Appendix A contains the text of Policy 5 Minimize loss of life, s~ruc- Cures, and natural resources from flooding and erosion from the Long Island Sound Coastal Management Plan. The proposed Policy 5 of Southold's Local Wa- terfront Revitalization Plan follows the same format. The following section discusses each of the policy standards specifically for Southold and how to apply each of the standards. These standards address Southold's specific con- ditions including erosion hazards, flood prone areas, and existing site condi- tions. The application cites existing regulations and recommends changes in the regulations to meet the standards in the Long Island Sound Coastal Manage- ment Plan, where applicable, for the Town of Southold. B. POLICY STANDARDS Policies Reflecting State Laws and for Setting Priorities In Erosion Control Stz-~ct~res 5.1 Comply with the Coastal Erosion Hazard A~ea statutes and regulations iu identified erosion hazard areas. 5.2 Comply with Floodplain w--Agement statutes and regulations in identified flood hazard areas. 5.3 ~[~tm{ze losses of h,mn- life and str~ctures from flooding and erosion hazards by usIn~ the foll~ing ~m,sgement measures ~hich are presented in order of priority: Ao Locate development and structures away from flooding and erosion IV-3 I I I I I I I I I I I I I I I I I I I B. Use vegetative non-struc~tral measures to manage flooding and erosion. C. Use natural protective features to manage flooding and erosion. D. Use structural measures to manage floodinE and erosion. The purpose of these three standards is to incorporate New York State laws and regulations into local codes and to establish a hierarchy of approaches to erosion protection. The Town of Southold has already incorporated requirements of the Coastal Erosion Hazard Area (Chapter 37 of the Town Code) and the Flood- plain Management Acts (Chapter 46 of the Town Cede) into its local codes and meets the first two standards. These amendments allow no permanent structures in the coastal hazard area where housing would be destroyed and lives endan- gered by wave action and high water levels. These areas are located primarily in the iow bluff and dune areas on Southold's Long Island Sound coast. The flood plain management requires that habitable space be located above the 100 year floodplain. On the Peconic side it is recommended that the code specific- ally include building on piles rather than using bulkheads. For the property owner, raising the building rather than the ground would be less expensive. A bulkhead that could affect nearby neighbors would not be required. The hierarchy to erosion control measures given above has not been adopted, and it is recommended that it be included in the application require- ments for a waterfront construction permit. Each applicant would have to demonstrate why the structure cannot be located outside of a flooding or ero- sion area; why vegetative or other non-structural measures would not protect the applicant's property; and why natural protective features are not suffi- cient before a permit could be granted. These measures should be included in both the Board of Trustees by-laws and in the Town of Southold Building Code. As discussed in Chapter III, using this hierarchy is particularly important on Southold's Long Island Sound high bluff areas and needs to be seriously consid- ered in all low bluff areas. Specifically, Section 100-239.4 of the Town Code should be amended so that the set back be 150 feet from the top of bluff or mean high water, whichever is more landward, on the Long Island Sound side. The same distance should be used on the Peconic Bay side where the shore has not been bulkheaded. Addi- tionally, vegetation that retains soils cannot be removed beyond 75 feet from the top of bluff or mean high water, whichever is more landward. The only exceptions include accessory structures for changing clothing, and less than IV-4 i I I i I I I I I I I I I I I I I I I a. locate structures away from hazard areas to limit generation of water-borne debris b. limit the amount of break-away structures including decks, walk- waYs and walls below the 100 year flood level 2. Limit the public cost of repair and cleanup resulting from damages to moveable structures within structural hazard areas: a. ensure that property owners recover debris resulting from damage to movable structures in structural hazard areas b. remove debris from public lands and waters within 60 days of damaging events 3. Include sea level rise calculations in siting and design of all major projects having more than a thirty year design life A-11 ! ! 100 square feet that could be located between the 75-foot vegetative buffer and the 150-foot setback. Natural Protective Features 5.4 Policy to protect and restore natural protective features. Natural protective features, such as bluffs and dunes, are found through- out the Town and must be protected to minimize erosion and flooding. The Town of Southold should adopt the same definition of natural protective features found in New York State regulations. They specifically include the nearshore area, beaches, bluffs, primary and secondary dunes, wetlands, and natural vege- tation. The alteration of natural protective features "might reduce or destroy the protection afforded other lands against erosion or high water, or lower the reserves of sand or other natural materials available to replenish storm losses through natural processes." It is recommended that these be added to the zon- in§ code, along with a prohibition on removing or lessening natural protective features' effectiveness, without a permit from the Town. Policy to Frotect Public and Fublic Trust Lands 5.5 Protect public lands and public tr~st lands and use of these lands ~hen u~dertaking all erosion or flood control projects. Portions of Southold's shoreline above Mean High Water (M~W) are in public ownership, and all lands below Mf{W are in public trust and administered by the Board of Trustees. This public trust dates back to the Andros Patent. A key responsibility of the Board of Trustees is to ensure that these lands are available and usable by the public. To accomplish this goal of access and availability, the Board must issue a permit for any construction below The Board must review each proposal and make a determination that the proposal will not result in the loss of these lands due to erosion. This review in- cludes not only the land which would be protected by the structure, but also updrift and downdrift property. If the Board determines that the structure is vital to protect the property but would lead to loss of other public trust land, then compensatory mitigation must be developed. This mitigation could be land banked before or could involve the Trust for Public Land, discussed under "Long-Term Coordination" in Chapter VI. IV- 5 I I ! I I I I I I I I I I I I i I I I Policy on~ater-Dependent Uses 5.6 Site Water-dependent uses and manage jetties and channels to limit adverse impacts on coastal processes. Marinas and other water-dependent users tend to locate in the protected creeks on the Peconic Bay side and in the two inlets on the Long Island Sound side of Southold. On the Long Island Sound side, three sites are zoned re- sort/residential and one site zoned MII. The MII site is no longer used and an undermined ramp remains from a fishing station. On the Peconic Bay side, Ori- ent Point is zoned MII for the ferries. Areas zoned as marinas are located in Orient Harbor, Cleves Point, Mills Creek area (2), Town Creek, and New Suffolk. Four areas zoned resort/residential are also found on the Peconic Bay side. Fishers Island contains two MII zones, and the rest of its shoreline is zoned residential. The marine-zoned areas should allow only water-dependent uses, such as marinas, fishing stations, and boat repair yards. The areas zoned resort/residential should be encouraged to develop as commercial ventures with public access. Non-water-dependent uses in these zones, such as restaurants, should be sited to allow the maximum possible use of the waterfront by the water-dependent uses. Siting the non-water-dependent uses near the road and sharing parking with the water-dependent uses will help accomplish the maximi- zation of water-dependent uses. Residential use prevents public access, and mamy resort type uses, such as conference centers and restaurants, provide water-enhanced experiences for the users. Policy on Expenditure of Public Fonds for Erosion Control 5.7 Expend public funds for m~gement or control of flooding or erosion only in a~eas of the coast ~hich will result in proportionate public benefit. Although most of the property that is threatened by erosion is privately owned, protection of that property is in the public's interest. Loss of the private property could restrict access and availability of lands in the public trust below MHW. However, the public benefits must be carefully weighed when considering expenditure of public funds. Within the jetty areas on the Long Island Sound side of Southold, the federal government is making large expendi- tures to protect navigation for fishing and commercial fleets, as well as for some recreational boating. The U.S. Army Corps of Engineers has made detailed benefit cost analyses and has found that the benefits outweigh the cost. IV- 6 However, the use of the dredged materials and the cost of installing a sand bypass system need to be investigated. A sand bypass system could speed the recovery of the beach on the east side of the inlet, leading to more public use of the area with its tourist benefits. The sand bypass system would also re- duce the cost of dredging because the sand would no longer move around the end of the jetty and deposit in the channel; it would be bypassed and deposited on the beach. Goldsmiths Inlet is not navigable and does not provide the benefits that Mattituck Inlet provides. The analyses for Goldsmiths should give careful consideration to the removal of the jetty. While removal of th~ jetty could reduce downdrift erosion, it could also lead to erosion on the west side of the jetty, and the impacts on drainage through the current inlet could be adverse. These issues would need to be addressed. On the Peconic Bay side, the same analyses should be done for dredged materials from creek mouths. Suffolk County bears the cost of this dredging, and the greatest public benefit should be derived from that expenditure. The analyses to date have focused on the navigational aspects, and the erosion and erosion protection benefits have not been fully included. On the exposed areas, the cost of developing the approach to groin field design would bring public benefits. Existing erosion problems could be solved 6r ameliorated, and future problems avoided. Groin fields covering whole lengths of shoreline could be laid out and their height, length, and spacing specified. The areas between the groins would have to be filled, and the source of material identi- fied. Groin field development projects could be combined with dredging proj- ects. The dredged materials could be placed between the groins, providing the benefits of both soft and hard solutions. By specifying the placement of sand between groins, DEC should be more amenable and not require upland disposal. This approach would benefit all owners sharing a given part of the shoreline, not just one property owner. ~olicy om Ltmitimg D=m-se im the Coastal Area 5.8 Limit potential loss of life a~d structural d~m~ge im all development im the coastal area. Many of the residences and buildings on the Peconic Bay side of Southold are subject of water damage and flooding. The Town's building code recognizes these dangers and has incorporated the applicable standards from the Federal Emergency Management Agency and the Uniform Building Code. These standards IV-7 I I I I I I I I I I I ! I I I I I I I need to be vigorously enforced. As discussed above, the use of pile supported structures, rather than building bulkheads, could limit structural damage with- out the drawbacks of bulkheads. In addition, the amount of debris that can break loose during a storm needs to be limited. The Town Code should have a requirement for recovering and cleaning up debris after a storm. This includes walkways, docks, piers, and other structures that were dislodged during the storm. These materials could cause further damage to other buildings, especially if a second storm closely follows the first. The requirement would include posting a bond when the structure is built. IV-8 I I I I I I I I I I I I I I I I I I I CHAPTER V. POST STORM RECOVERY POLICIES A. POST STOI~ RECOVERY Introduction The common tendency after a damaging storm is to return to the same situa- tion as before the storm, whether or not that situation was desirable. The post storm rebuilding should be aimed at preventing and minimizing erosion and flooding. The approach will vary by the type of damage inflicted by the storm and by the goals of each of the common management units. In addition, the permitting procedures may constrain or delay certain actions in the rebuilding process. This chapter discusses the approach to be taken in each of the common management units, and how existing permitting procedures may be used to achieve the goals of the units. Post Sto~Recovery Goals by Co~mon~n~asement Unit Lone Island Sound Side On Southold's Long Island Sound coast, the major cause of damage during a storm is wave action leading to erosion of the bluffs and loss of the dunes. The storm could also seriously damage the jetties at Mattituck and Goldsmiths Inlets. Inundation of large inland areas does not typically occur. Jetty Areas A storm could flank the jetties, causing the inlet to migrate out of its present channel. In this case, the flanked area should be filled so that the protected channel is returned. A migrating channel could lead to erosion of previously protected property and instability in the inlet. The storm could seriously damage or destroy the jetties. If Mattituck Inlet jetties are destroyed, they should be rebuilt. The U.S. Army Corps of Engineers has studied different solutions for the stabilization of Mattituck Inlet and has found that maintaining the channel by dredging and rebuilding the V-1 I I I I I I I I I I I I I I I I I I I existing jetties provide the best solution. The economic hardship on busi- nesses in Mattituck Inlet would be unbearable, and they would either relocate or close. In either case, Southold would lose jobs from its economic base and part of its maritime tradition. Therefore, rebuilding of the jetties to pro- tect the inlet and its uses should be done as quickly as possible. For Goldsmiths Inlet, the decision is not as straightforward. The origi- nal purpose of the jetties -- a public park -- is no longer envisioned, and the jetties are causing erosion along Horton Lane Beach, which is heavily used by the public. Serious study and consideration should be given to removal of the jetty if it is destroyed or damaged during a storm. The effects on the down- drift beaches need to be analyzed prior to making this decision. The waters that are now drained by the inlet would become formally connected tidal wet- lands that have their own unique habitat value. Ways to protect these wetlands and to prevent them from becoming a public hazard or nuisance would have to be developed. Based on these studies, the most beneficial course of action in the case of heavy damage to the jetties can be selected. The final situation around the jetties is severe erosion of the downdrift beaches and loss of dunes. In both areas, the beach should be refilled with sand, from the updrift side of the jetties if possible. These beaches are valuable and heavily used by the public. The beaches would accrete sand slowly after being damaged, but this could lead to further downdrift erosion because of the lack of sand. Therefore, refilling the beach is warranted. At Matti- tuck Inlet, the erosion of the beach could also cause a breach, and the inlet would migrate to outside of the current channel~ The new channel would proba- bly not be navigable by the fishing boats and could cause the same type of dislocation as loss of the jetties. Low Bluffs and Dunes During large storms, the waves erode the bluffs at their toe, which leads to slumping. The slumping brings some new sediment to the beaches. The damage is normally loss of bluff and encroachment into a yard area. This excludes those cases where the principal residences are endangered, as is discussed below under Emergency Procedures. In the dune areas, flooding often occurs during the storm, eroding the dunes and causing water damage to personal property. V-2 I I ! I I I I I I I I I I I I I I I ! The management objective in the low bluffs and dunes common management areas is to reduce the number of hard erosion protection structures and en- courage soft approaches, such as vegetative cover. However~ existing struc- tures that are either grandfathered or permitted can be rebuilt as-of-right. Some of the erosion protective structures will undoubtable be rebuilt almost immediately. However, the Town and the Board of Trustees~ focus here should not be on rebuilding everything immediately -- including erosion protection structures -- but on how the current damage to homes can be corrected and future damage mini- mized. Applications for new structures should be carefully reviewed rather than granted quickly. The effects of new structures on surrounding properties must be shown by the applicant. If a permit is granted, the conditions should include meeting the setback requirements for the principal structure and the full width of native vegetation planting. The construction work, if permitted, would have to include meeting these requirements and not be done at a later time. In many cases, the homeowner will have funds from flood insurance te pay for the reconstruction and moving of the house to beyond the setback limit. Therefore, requiring the homeowner to meet these requirements would not cause a financial hardship, as long as the property has flood insurance. As part of the rebuilding, the Buildings Department needs to examine the condition of the house and its likelihood of being damaged again in the next storm before issuing its permit. If a house ceuld be damaged in the next storm, the owner should be required te rebuild it so that the damage would not eccur again. This could include moving the house further away from the shore- line on a new foundation. In a dune area, raising the house above the flood area could be appropriate. Areas of High Bluffs The toe of high bluffs is eroded during a storm, and then the bluffs slump down because of the lack of support. The slumping of the high bluffs supplies large volumes of sand and gravel to the beaches. Each linear foot of a 50- foot-high bluff supplies about 2 cubic yards of sediment for each landward foot of erosion. These bluffs are of treat importance in maintaining the beaches and protecting the areas of low bluffs and dunes, which are more susceptible to landward erosion that threatens homes. The management objective of this common management unit is to minimize the building of groins and erosion protection V-3 structures to the extent possible, without causing loss of property or struc- tures. Therefore, the post storm recovery approach should be the same as dur- ing the normal permitting process; the overwhelming need for erosion protection structure must be demonstrated by the applicant before a permit is issued. For the rebuilding of damaged structures or the building of new erosion control structures, the Board should consider the intensity of the storm that would likely cause more damage. In Florida, the homeowner would receive a permit only if a storm with a return period of 15 years or less caused damage. Emotional appeals of the property owners who feel their lands are in danger can be persuasive, but the overall needs of the shoreline must be considered first. Measures, such as planting vegetation along the shoreline, must be analyzed first, and the permit for an erosion protection will be issued only when such methods are shown to be infeasible. Peconic Bay Side On the Peconic Bay side of Southold, where almost all of the shoreline is heavily protected, the focus of post storm recovery policies is on segment or reach long analysis, rather than on individual structures. If a whole length of similar shoreline is considered as one, solutions that protect all property owners can be developed and implemented. The aggregate cost for protecting a whole length of shoreline will probably be less than the sum totals that the property owners would pay. The Town could consider setting up special taxing districts to pay for the study, design, and construction of the these groin fields. However, this could be prove to be administratively burdensome. Alternatively, the homeowners could consider setting up their own special fund similar to a homeowners' association. While the Town and the Board of Trustees do not have the direct power to cause a group of properties to act in concert, the post storm review process can lend itself to this approach. If a group of neighbors submitted a joint application, the effects of the proposed structures on neighbors would already have been demonstrated, whereas if a single property owner submits an applica- tion, the effects of the proposed structure on neighbors would still need to be demonstrated. Using this group approach would help achieve the management objectives in all common management units on the Peconic Bay shoreline, except for flood- prone areas. These areas have an additional goal of preventing further flood I I I I I I I I I I I ! I I I I' I I I damage. Therefore, the Buildings Department should not issue permits unless flood-proofing can be demonstrated. As discussed above, raising the building on piles rather than raising the land behind a bulkhead may be a preferable approach. Emerzencv Permits The above recommendations apply when a structure is not in imminent danger of collapse or significant structural damage. Certain storms will cause damage that must be repaired under emergency conditions. Homes and principal resi- dences must sometimes be immediately repaired or they will collapse or become permanently damaged. This can be caused by falling trees, trucks striking the house, and coastal erosion. An emergency situation for a house or principal residence is often defined as when 25 percent of the floor area is close to collapse or permanent structural damage as certified by a professional engineer or licensed architect. This is a situation that is handled by the Buildings Department, and they have proper procedures in place. Shore protection structures can generally be mended temporarily while a decision on the type and extent of the final restoration is being made. The heavy construction materials and type of structural supports make this delay possible. According to existing state regulations, an existing erosion protec- tion structure that is properly permitted or grandfathered can be repaired without a permit. However, many groin fields, especially on the Peconic Bay shoreline, are not truly functioning structures. Therefore, if erosion control structures are being emergency repaired, the building inspector or an indepen- dent should inspect the site and certify that it was a functioning s~ructure. If the structure was not functional, the work should be halted. As discussed in Chapter VI, "Implementation Options," an inventory of functioning structures should be mapped and photographed in the future. Trying to determine if a structure was functioning after having been damaged is likely to lead to dis- putes. This inventory would address that issue. The only true emergency situation that would require a discretionary per- mit is when the sole public access to a group of houses is about to be de- stroyed or when a vital public utility, such as water or electricity, is about to be severed. Then, the only way to protect the sole access or utility from the next storm would be to build an erosion control structure. In cases such as this, the State Environmental Quality Review Act (SEQRA) lists the action as V-5 I I I I I I I I I I I I I I I I I I I exempt, and the New York State Department of Environmental Conservation (DEC) has emergency procedures for permitting under its regulations. The Corps of Eng£meers has similar procedures. Therefore, an emergency permit should only be issued for protection of sole access ways and vital utilities, and existing regulatory emergency procedures should be used. V-6 I I I I I I I I I I I I I I I I I I I CHAPTEK VI, IHPLE14ENTATION OPTIONS A. IMPLEMENTATION OPTIONS Studies Because of the breadth and variety of Southold's shoreline, the recommen- dations contained in this report are general in nature. To fully implement these recommendations, detailed study of each of the reaches and common manage- ment units is recommended. The scope of work for the first reach -- Duck Pond Point to Horton Point -- has been developed, and the study is to begin as soon as funding is available. Another important task that can be done almost immediately is to develop an inventory of functioning erosion protection structures. Functioning coastal erosion structures that are damaged in a storm can be repaired without a per- mit. As part of the post storm recovery approach, restrictions on rebuilding erosion control structures have been recommended. At the current time, no inventory of functioning structures exists, and disputes could arise if post storm Judgements are made on the functionality of structures. This inventory should mapped, photographed, and videotaped; it will be important in the imple- mentation of this post storm recovery policy. In addition, this data base can be used to determine the effects of structures on coastal erosion. These data could refine the design of groin fields so that they protect structures and do not cause erosion elsewhere. The jetties at Mattituck Inlet have caused downdrift erosion and have threatened the dunes between the inlet and Oregon Hills. However, the commer- cial and recreational uses in Mattttuck Inlet are an essential part of the character and economic life of Southold, and the jetties are necessary for navigation. A sand bypassing could address the erosion problem and reduce the .expense of dredging the channel. A study of the feasibility and cost of a sand 'bypassing system is recommended. In Chapter V, "Post Storm Recovery Policies," the problem of rebuilding the jetties at Goldsmith Inlet if they are damaged in a storm was discussed. These jetties have led to erosion at heavily used public beaches. The effects of removing the jetties and closing the inlets could be studied prior to a damaging storm, forcing a decision without sufficient study. This particular VI- 1 study would rely on the findings of the detailed reach study of Duck Pond Point to Horton Point. Capital Projects Without the studies discussed above, no capital projects can be recom- mended at this time. Prior to committing to capital development, the public benefits need to be more firmly established and the costs estimated in detail. Southold could implement several demonstration projects with its own resources. These include a natural vegetation nursery to determine which plantings do well and provide the best erosion protection. The Town could erect sand fencing, such as the New York State Department of Environmental Conservation (DEC) is doing at New Suffolk, on public dune areas. Lon~-Ter~ Coor~{-~tion Government A~encies Coordination with the state level of government will benefit the Town of Southold. First, the current coordination with the Division of Coastal Resources and Waterfront Revitalization in the Department of State should be continued. This division has been providing important guidance and funding to Southold for the development and protection of the coastal area. This rela- tionship should continue. Second, long-term coordination is with Suffolk County and DEC for the use and placement of dredged materials~ Thousands of cubic yards of sand are dredged every year on the Peconic Bay shore, and Southold has had little, if any, input into the placement of that sand. The dredged material is a very important resource that can address many of the erosion problems in the creek mouths and along the exposed shoreline. A committee comprising the Town of Sout~old, Suffolk County, and DEC should be set up to review the upcoming dredging projects and decide where to place the sand. These decisions will have to made yearly because the erosion patterns change based on the direction and severity of the storms~ This committee could be the most important tool available to Southold for use of the dredged materials to alleviate its erosion problems along the Peconic Bay shores. VI-2 The final part is internal to the Town of Southold. The Building Depart- ment can be instrumental in alleviating damages from coastal erosion. The first part is in the Building and Zoning Codes. The Building Code specifies flood protection and structural requirements. These requirements can be strengthened, especially in flood-prone management units. The Zoning Code can provide for setbacks and soil-retaining plants. The second important area is enforcement of the codes. The Building Inspector should become familiar with coastal erosion and methods of minimizing erosion. This area of expertise is as important as knowledge of structural system in the Town of Southold, with its long coastal expanse. Private Foundations Parts of Southold's shoreline are in public ownership and other parts, such as Meadow Beach Preserve are held by the Trust for Public Lands (Trust), a private organization that holds and protects ecologically valuable land. Those areas of shoreline in public ownership must be kept for use of Town residents and visitors. The Town should work with the Trust to preserve valuable natural lands, such as marches and wetlands. The Trust will often set up trades where a developer will deed a valuable natural site to them in return for another site that would be easier to develop. This private sector entity can raise funds to protect natural protective features and ecologically significant sites, where the Town could not. By working with the Trust, the Town would have an instrument to direct development and protect sites on a smaller scale than can normally be achieved through zoning or other regulation. VI-3 COASTAL ENGINEERING GLOSSARY (F~0H SHORE PROTECTION MANUAL, 1984) ACCRETION. Buildup of land on a beach either by action of the forces of nature or an act of man. AE0?3AN SANDS. Sediment of sand size or smaller that have been transported by winds. A~0NGSHORE. Parallel to and near the shoreline (~0NGSH0~). AR~0R UNIT. Relatively large quarrystone or concrete shape that is used for wave protection structures. A'A-£~UATION. The lessening of the amplitude of a wave with distance from the origin or through structural or landform interference. BA~H0~. Zone of the shore or beach lying between the foreshore and coast- line. Acted on by waves only during extreme storm events. BA~. Submerged or emerged embankment of sand, gravel, or other unconsolidated material built on the sea floor in shallow water by waves and currents. RAR~ BEACH. A bar parallel to the shore, the crest of which is above normal high water level. BA~IE~ LAGOON. A bay separated from the open ocean by barrier islands. BA'£H¥~X. The measurement of depths of water in oceans, seas, and lakes. BA~0UTH BA~. A bar extending partly or entirely across the mouth of a bay. B~A~H. The zone of unconsolidated material that extends landward from the low water line to the place where there is a marked change in material of physiographic form, or to the line of permanent vegetation. Consists of a FORESHORE and BAGKSHORE. BEACH BERM. Nearly horizontal part of a beach or hackshore formed by ~he depo- sition of material by wave action. BEACH EROSION. The removal of beach materials by wave action, tidal currents, littoral currents, or winds. BEACH FILL (NOURIS~iNT). Material placed on a beach to renourish an eroding beach, or the act of beach replenishment either naturally or artificially. BEACH PROFILE. The intersection of the ground surface with a vertical plane; may extend from the top of the dune line to a seaward limit of sand movement. BEACH SCARP. An almost vertical slope along the beach caused by erosion due to wave action. G-1 BEACH~DTH. The horizontal dimension of the beach measured normal to the shoreline. BLu~ (E$CAI~I~IT). A high steep bank or cliff. BREAI~R. A wave breaking on a shore, over a reef, etc. BIIEA~ATKI~. A structure protecting a shore area, harbor, anchorage, or basin from waves. BUL~xKAB. A structure that retains or prevents sliding of the land, and pro- tects the upland from wave action. BYPASSING, SAlqD. Hydraulic or mechanical movement of sand from the accreting updrift side to the eroding downdrift side of an inlet or harbor entrance. CHAleT (TIDAL) DATUH. The plane or level to which soundings, elevations, or tide heights are referred. COAST. A strip of land of indefinite width that extends from the shoreline inland to the first major change in terrain features. COAS~II~. Line separating the coast and the shore; more commonly, the boun- dary between land and water. CU]IRENT. A flow of water, typically generated by wave action, tidal fluctua- tions, or winds. CUSPA~ BAIl. A crescent-shaped bar uniting with the shore at each end. DECAY OF WAVES. The change waves undergo after leaving a generating area and passing through a calm or region of lighter winds. DEE~ ~A~]~I. Water deep enough that waves are not affected by the ocean bottom. DEFLATION. The removal of loose material from a beach or other land surface by wind action. DEI~Iqt. The vertical distance from a specified tidal datum to the sea floor. DI~aACTION. The phenomenon by which energy is transmitted laterally along a wave crest. In a coastal sense, it occurs when a wave train is inter- rupted by a structure or seafloor elevations differences in such a way that waves are propagated into the sheltered region of the structure. DAu~ALTIDE. A period or cycle of approximately one tidal day. DOYND~IFT. The direction of predominant movement of littoral materials. DU~ES. Ridges or mounds of loose, unconsolidated material, usually sand. ~Y~ITf. An indentation into the shoreline forming an open bay. ESC~. A line of cliffs or steep slopes facing in one general direction that are caused by erosion or faulting. ESTUARY. Portion of river that is affected by tides or region of a river mouth in which fresh and salt water mix. --x'x~AT~OPICAL STO]~H. Storms that develop in the mid-latitudes in response to the interaction of warm and cool air masses, commonly referred to as northeasters. FETCH. The area in which seas are generated by wind having a fairly constant direction and speed. The horizontal distance (in the direction of the wind) over which a wind generates seas. FORESHORE. The part of the shore lying between the crest of the seaward berm and the ordinary low-water mark. GEOHORI~IOLOG¥. That branch of both physiography and geology that deals with the form of the earth, the general configuration of its surface, and the changes that take place in the evolution of landform. ~ABIENT. Rate of change with respect to winds, currents, or wave heights. GROIN. A shore protection structure built perpendicular to the shore to trap littoral material or retard erosion of the shore. g~AnTmND. A high steep-faced promontory extending into the sea. EI~t TIDE (HIGH ~£~). Maximum elevation reached by each rising tide. BI~gg~ HIGH ~A'~. The higher of the two high waters of any tidal day. HINDCASTING, ~AVE. The use of historic synoptic wind charts to calculate char- acteristics of waves that occurred at some past time. ~usAICANE. An intense tropical cyclone in which winds tend to spiral inward toward a core of Iow pressure. Maximum surface wind velocities equal or exceed 75 miles per hour for several minutes or longer at some point. II~LET. A short narrow waterway connecting a bay, lagoon, or similar body of water with a large parent body of water. J~'1-£~. On open seacoasts, a structure extending into a body of water that is designed to prevent shoaling of a channel by littoral materials. L~GOON. A shallow body of water usually connected to the sea. LITTOHAL. Of or pertaining to a s~ore, especially of the sea. LT~fOP,~LMATEPJAL (DP~IFT). The sedimentary material moved in the littoral zone under the influence of waves and currents. LITTOHAL TRANSPORT. The movement of littoral drift in the littoral zone by waves and currents. G-3 LITTORAL TRANSPORT PATE. Rate of transport of sedimentary material either parallel or perpendicular to the shore. LONGSHOP, E CUP~NT. A current moving essentially parallel to the shore, usually generated by waves breaking at an angle to the shoreline. LOW TIDE (LOW WATER). Minimum elevation reached by each falling tide. LOW~-.~.LO~ ~AT~. The lower of the two low waters of any tidal day. SEA L~v~L. The average height of the surface of the sea for all stages of the tide over a 19-year period. (HIGHER HIGH, HIGH, LOW, LOw~ LOW) WAT~-~. Average height of the (higher high, high, Iow, lower Iow) waters over a 19-year period. MORAINE. A ridge, mound, or irregular mass of boulders, gravel, sand, and clay, carried in or on a glacier. A deposit of such a material left on the ground by a glacier. N~-ARSHOP~ ZONE. An indefinite zone extending seaward from the shoreline well beyond the breaker zone. NECK. A narrow strip of land connecting a peninsula with the mainland. OFFSHORE. The comparatively flat zone of variable width, extending from the breaker zone to the seaward edge of the Continental Shelf. OFFSHORE/ONSHORE CURRENT. A current directed offshore/onshore of the shore. POCKET BEACH. A beach, usually small, located between two littoral barriers. I~¥E'f~ENT. A facing of stone, concrete, etc., built to protect erosion by wave action or currents. SEAS. Waves caused by wind at the place and time of observation. SEAWAYJ.. A structure separating land and water areas, typically designed to prevent erosion or other damage due to wave action. SE~IDAuK~AL TIDE. A tide with two high and two low waters in a tidal day. SWAY~ ~A'£~-~. Water of such depth that surface waves are noticeably affected. by bottom topography. SHOAL. (N) A detached elevation of sea bottom, composed of any material except rock or coral, that may endanger surface navigation. (V) To become shal- low gradually or to proceed from a 'greater to a lesser depth of water. SHORE. The narrow strip of land in immediate contact with the sea. SHOHEFAGE (INSHORE ZONE). The narrow zone seaward from the low tide SHORELINE, covered by water, over which the beach sands and gravels actively oscil- late with changing wave conditions. G-4 SHORELINE. The intersection of a specified plane of water with the shore or beach (typically taken as mean high water or mean higher high water). SOIL C~m~SIFICATION. An arbitrary division of a continuous scale of grain sizes. SPIT. A small point of land or a narrow shoal projecting into a body of water from the shore. STOP~ S~GE. A rise above nbrmal water level on the open coast due to the ac- tion of wind stress on the water surface or atmospheric pressure differen- tials associated with storm events. SUP~F ZONE. The area of breaking waves. ~w~LL. Wind-generated waves that have traveled out of their generating area. TIDAL DAY. The time of the rotation of the earth with respect to the moon, or the interval between two successive upper transits of the moon over the meridian of a place, approximately 2~.84 solar days. TIDAL HA~GE. The difference in height between consecutive high and low waters. TIDE. The periodic rising and falling of the water that results from the gra- vitational attraction of the moon and sun and other astronomical bodies acting on the rotating earth. TO,BOLO. A bar or spit that connects an island to the mainland or to another island. TOPOGRAPHY. The configuration of a surface, including its relief and the posi- tions of its streams, roads, buildings, etc. T~OPIC4~L STOP~. A tropical cyclone with maximum winds less than 75 miles per hour. ~I~DB_IFT. The direction opposite that of the predominant movement of littoral materials. WA~E C?.r~ATE. The combination of waves of different heights, periods, and directions. WAYE GHEST. The highest point on a wave. WA~E DIRECTION. The direction from which a wave approaches. WAVE HEI~wl'. The vertical distance between a crest and the preceding trough. WA~E LENGTH. The horizontal distance between similar points on two successive waves measured perpendicular to the wave crests. WAVK P]~tIOD. The time for a wave crest to traverse a distance equal to one wave length. G-5 WAVE PI~OPAGATION. The transmission of waves through water. WAVE P. EFRACTION. The process by which the direction of a wave moving in shal- low water is altered as the part of the wave advancing in shallower water moves more slowly, causing the wave crest to bend toward the shallower water. WAVE TBAI~. A series of waves from the same direction. WAVE. Waves being formed and built up by the wind. G-6 APPENDIX A: LONG ISLAND SOUND EROSION HANAGEHENT POLICIES A, LONG ISLAND SOUND COASTAL~L~NAGEI~ENT PLAN Policy 5 Minimize loss of life, structures, and natural resources from flood- in~ and erosion. 5.1 Comply With the Coastal Erosion Hazard Area statutes and re~mlations in identified erosion hazard areas. 5.2 5.3 5.4 5.5 5.6 5.7 Comply with Floodplaim llanagement statutes and re~mlations in identified flood hazard areas. Hinimize losses of~mon life and structures from floodinE and erosion hazards by usinE the following m-~-gement measures vhich are presented in order of priority: Protect and restore natural protective features. Protect public lands and public trust lands and use of these lands when undertaking all erosion or flood control projects. Site water-dependent uses and manage navigation ~rastruc~ure to 14m~t adverse impacts on coastal processes. Expend public funds for management or control of flooding or erosion haz- ards only in areas of the coast which will restttt in propor~ionate public benefit. 5.8 Limit potential loss of life and struc~ttral a-m-se in all development in ~he eoas2al area. A-1 Policy 5 Minimize loss of life, structures, and natural resources from flood- ing and erosion. Within the Long Island Sound coastal area, there are presently more than 8,200 buildings and other structures located in special flood hazard areas, and over 1,200 buildings and other structures seaward of the present coastal ero- sion hazard area boundary. In response to existing or perceived erosion and flood hazards, many landowners have constructed erosion control structures. Approximately 50 percent of the Sound shoreline has been armored with erosion control structures, and the trend is continuing. In Suffolk County, for exam- ple, only 8.96 miles of 132.5 miles of the Sound shoreline was engineered with riprap, bulkheads, or seawalls in 1969. Today, 43.7 miles of the county's shoreline are hardened. This significant increase in the miles of hardened shoreline is not associated with water-dependent uses in Maritime Centers, but rather for uses that do not have a functional relationship to coastal waters. There are many erosion control structures located within the Long Island Sound coastal area that are not necessary for erosion protection. Erosion control structures often contribute to erosion both on and off the site due to poor design and siting and lack of downdrift remediatton. In- creased erosion, aesthetic impairments, loss of public recreational resources, loss of habitats, and water quality degradation can result from individual hardening of the shoreline. The cumulative impact of these structures is potentially large. Before a permit is granted to allow construction of hard erosion control structures, the purpose, function, impact, and alternatives to the project need to be carefully evaluated to determine that the structures are necessary and to avoid adverse impacts. Although the Long Island Sound shoreline has been heavily fortified, there are significant stretches of the coast that remain in a natural state. The natural shoreline has an inherent natural, social, and economic value that should be respected to ensure continuing benefits to the state and the region. Consequently, those portions of the Sound shoreline that are not fortified should generally remain in a natural condition to respond to coastal processes. Where feasible and appropriate, portions of the shoreline that have been hard- ened should be returned to a natural condition. Development and redevelopment in hazard areas need to be managed to reduce exposure to coastal hazards. Hardening of the shoreline is to be avoided, except when alternative means, such as soft engineering alternatives, beach A-2 nourishment, revegetation, offshore bar building, or inlet sand bypassing, are impractical to protect principal structures or extensive public investment (land, infrastructure, facilities). Areas of extensive public investment in- clude City Island and the Throgs Neck in the Bronx, the Cross Island Parkway section of Queens, Bayville, the Asharoken tombolo, Sunken Meadow State Park~ portions of the identified Areas for Concentrated Development, and the ten Maritime Centers. Barrier landforms that protect significant public investment or natural resources should be maintained. Soft structural protection methods are to be used to conform with the natural coastal processes. Barrier beach landforms should be maintained by using clean compatible dredge material when feasible, for beach nourishment, offshore bar building, or marsh creation projects. In suitable locations and where appropriate, interpretative materials could be considered to enhance the public's understanding of natural coastal processes. This policy seeks to protect life, structures, and natural resources from flooding and erosion hazards throughout the Long Island Sound coastal area. The policy reflects state flooding and erosion regulations, and provides mea- sures for reduction of hazards and protection of resources. Policy standards are divided into eight sections. The first two sections reflect state flooding and erosion regulations. Section 3 presents standards directed at protection of life and property, including measures for minimizing losses from flooding and erosion arranged in order of priority, ranging from avoidance to hard structural approaches. Section 4 addresses natural protec- tive features. Section 5 addresses protection of public funds or public trust lands. Measures for water-dependent uses and navigation are provided in sec- tion 6. Section 7 establishes conditions for expenditure of public funds for management of flood and erosion hazards contingent on public benefit. Section 8 addresses reduction of hazards through emergency planning and building con- struction standards. ~olicy Standards 5.1 Comply vith the Coastal Erosion Hazard Area statutes and reEulations in identified erosion hazard areas. A-3 I I I I I I I I I I I I I I I I I I I 5.2 Comply with Floodplain HanaEement statutes and reEulations in identified flood hazard areas. 5.3 Hinimize losses of human life and structures from flooding and erosion hazards by using the following management measures which are presented in order of priority: Coastal Barrier Resource Area is any one of the designated and mapped areas under the Coastal Barrier Resources Act of 1982, (P.L. 97-348), and any areas designated and mapped under the Coastal Barrier Improvement Act of 1990 (P.L. i01-59i), as administered by the U.S. Fish and Wildlife Service, and any future designations that may occur through amendments co these laws. Coastal Erosion Hazard Area is any coastal area included within the Erosion Hazard Area as designated by the State Department of Environmental Conservation pursuant to the Coastal Erosion Hazard Areas AcC of 1981 (Article 34 of the Environmental Conservation Law), and any coastal area included within a V-zone as designated on Flood Insurance Rate Maps prepared by the Federal Emergency Management A~ency pursuant to the National Flood Insurance Act of 1968 (P.L. 90-~48) and the Flood Disaster Protection Act of 1973 (P.L. 93-23~]. Natural protective features are beaches, dunes, shoals, bars, spits, barrier islands, bluffs and wetlands; and associated natural vegetation. Minimize potential loss and damage by locating development and structures away from flooding and erosion hazards. 1. Avoid developing new structures and uses or reconstruction of struc- tures damaged by 50% or more of their value in areas which are likely to be exposed to hazards unless: a. the structure or use functionally requires a location on the coast or in coastal waters, or b. the new development would be located in an area of substantial public investment, or the new structure or use is necessary for shoreline development which: (1) reinforces the role of Maritime Centers in concentrating water-dependent uses, and (2) would not result in impairment of natural resources Locate new structure which are not functionally dependent on a loca- tion on or in coastal waters, are not in areas of substantial public investment, or do not reinforce the role of a Maritime Center, as far away from flooding and erosion hazards as possible. a. No development is permitted in natural protective feature areas, except for artificial beach nourishment and coastal structures including docks, piers, wharves, groins, jetties, seawalls, bulkheads, breakwaters, and revetments. b. Locate new development away from coastal hazards associated with inlet areas. c. Avoid hazards by siting structures to maximize the distance from Coastal Erosion Hazard Areas. d. Provide sufficient lot depth to allow relocation of structures and maintenance of required setbacks over a period of thirty years. 3. Where practical, moving existing structures and development which are exposed to hazards away from the hazards is preferred over maintain- ing structures and development in place. Maintaining existing devel- opment and structures in hazard areas may be warranted for: a. structures which functionally require a location on the coast or in coastal waters, or b. water-dependent uses which, by the nature of the use, cannot avoid exposure to hazards, or c. sites in areas with extensive public investment, public infra- structure, or major public facilities, or d. sites where relocation or an existing structure is not practical 4. Provide public infrastructure in or near identified high velocity flood zones, structural hazards areas or natural protective features only if the infrastructure: a. will not promote new development or expansion of existing devel- opment in a Coastal Barrier Resource Area or a Coastal Erosion Hazard Area A-5 b. is designed in a manner which will not impair protective capaci- ties of natural protective features, and c. is designed to avoid or withstand damage from flooding and erosion. Use vegetative non-structural measures which have a reasonable probability of managing flooding and erosion based on shoreline characteristics in- cluding exposure, geometry, and sediment composition. Use vegetative measures to increase protective capacities of natural protective features at every opportunity. Enhance existing natural protective features and use non-structural mea- sures which have a reasonable probability of managing erosion. 1. Enhance the protective capabilities of beaches by using fill, artifi- cial nourishment, dredge disposal, or by restoring coastal processes according to the following standards: a. Use only clean sand or gravel with a grain size equivalent to or slightly larger than the native material at the project site. b. Design criteria for enhancing the protective capabilities of beaches should not exceed the level necessary to achieve protec- tion from a 30 year storm, except where there is an overriding public benefit. Provide for sand by-passing at engineered inlets or other shore protection structures to maintain coastal processes and protec- tive capabilities of beaches. 2. Protect and enhance existing dunes or create new dunes using fill, artificial nourishment, or entrapment of windborne sand. a. Use only clean sand with a grain size equivalent or slightly larger than native dune material b. Design criteria for created dunes should not exceed the overtop- ping height defined by the 30 year storm, except where there is an overriding public benefit. c. Enhance existing or created dunes using snow fencing and dune vegetation. d. Construct and provide for use of walkovers to prevent pedestrian damage to existing and enhanced dunes. A-6 Increase protective capacity of natural protective features using practical vegetative measures in association with all other enhance- ment efforts. Use hard structured erosion protection measures for control of erosion only where: 1. Avoidance of the hazard is not practicable because a structure is: functionally dependent on a location on or in coastal waters; located in an area of extensive public investment; or reinforces the role of Maritime Centers. 2. Vegetative approaches to controlling erosion are not effective. 3. Enhancement of natural protective features would not prove practical in providing erosion protection. Construction of a hard structure is the only practical design consid- eration and is essential to protecting the principal use. 5. The proposed hard structural erosion protection measures: a. are limited to the minimum scale necessary b. are based on sound engineering practices 6. Practical vegetative methods have been included in the project design and implementation. 7. Adequate mitigation is provided and maintained to ensure that there is no adverse impact to adjacent property, to natural coastal pro- cesses and natural resources, and, if undertaken by a private proper- ty owner, does not incur significant direct or indirect public costs. Maximize the protective capabilities of natural protective features by: 1. avoiding alteration or interference with shorelines in a natural condition 2. enhancing existing natural protective features 3. restoring the condition of impaired natural features wherever practical 4. using practical vegetative approaches to stabilize natural shoreline features 5. managing activities to limit damage to, or reverse damage which has diminished, the protective capacities of the natural shdreline A-7 providing relevant signage or other educational or interpretative material to increase public awareness of the importance of natural protective fsatures Minimize interference with natural coastal processes. 1. Provide for natural supply and movement of unconsolidated materials and for water and wind transport. 2. Limit intrusion of structures into coastal water. 3. Limited interference with coastal processes may be allowed where the principal purpose of the structure is necessary to: a. simulate natural processes where existing structures have al- tered the coast, or b. provide necessary public benefits for flooding and erosion pro- tection, or c. provide for the efficient operation of water-dependent uses, and provided that d. mitigation is provided and maintained to ensure that there is no adverse impact to adjacent property, to natural coastal pro- cesses and natural resources, and, if undertaken by a private property owner, does not incur significant direct or indirect public costs 5.5 Protect public lands and public t~'ust lands and use of these lands vhen undertaking all erosion or flood control projects. Retain ownership of public trust lands which have become upland areas due to fill or accretion resulting from erosion control projects. Avoid losses or likely losses of public trust lands or use of these lands, including public access along the shore, which can be reasonably attrib- uted to or anticipated to result from erosion protection structures. Provide and maintain compensatory mitigation of unavoidable impacts to ensure that there is no adverse impact to adjacent property, to natural coastal processes and natural resources or, to public trust lands and their use. A-8 Site water-dependent uses and ~ana~e navigation infrastructure to limit adverse impacts on coastal processes. Except in Maritime Centers, site new water-dependent uses in erosion haz- ard areas only if the use could not practicably be located outside the hazard area. Manage navigation channels to limit adverse impacts on coastal processes: 1. Design channel construction and maintenance to protect and enhance natural protective features and prevent destabilization of adjacent areas by: a. using dredging setbacks and slopes from established channel edges b. locating channels away from erodible features, where feasible c. preventing adverse alteration of basin hydrology d. including by-passing methods to maintain navigability and reduce frequency of dredging 2. Use clean dredged material as beach nourishment whenever the grain size of the dredged material is the same size or slightly larger than the grain size of the potential recipient beach. Manage stabilized inlets to limit adverse impacts on coastal processes 1 Include sand bypassing at all engineered or stabilized inlets which interrupt littoral processes. 2 Manage flood and ebb tidal deltas to simulate natural processes. 3 Avoid extending jetties when it will increase disruption of coastal processes. 5.7 Expend public funds for unsgement or control of flooding or erosion haz- ards only in areas of the coast which vii1 result in proportionate public benefit. Give priority in expenditure of public funds to actions which protect public heaI~h and safety, mitigaCe past flooding and erosion problems, pro~ecC areas of inCensive development, and pro~ecC subs~anrial public invesCmenC (land, infrastructure, facilities]. A-9 I I I I I I I I I I I I I I I I I I I Expenditure of public funds for flooding or erosion control projects; 1. is limited to those circumstances where public benefits clearly ex- ceed public costs 2. is prohibited for the exclusive purpose of flooding or erosion pro- tection for private development, and 3. may be apportioned among each level of participating governmental authority according to the relative public benefit accrued. Factors to be used in determining public benefit attributable to the pro- posed flood or erosion control measure include: 1. economic benefits derived from protection of public infrastructure and investment and protection of water-dependent commerce, or 2. protection of significant natural resources and maintenance or resto- ration or coastal processes, or 3. integrity of natural protective features, or 4. extent of public investment, or 5. extent of existing or potential use Application of these factors indicate that public expenditure for erosion and flood control projects may be warranted in~ City Island and the Throgs Neck in the Bronx, the Cross Island Parkway section of Queens, Ba3zville, the Asharoken tombolo, Sunken Meadow State Park, Wildwood S~ate Park, portions of the identi- fied Areas for Concentrated Development, and the Maritime Center of Port Chester, Mamaroneck Harbor, New Rochelle-Echo BaM, City Island, Port Washington-Manorhaven, Glen Cove, Huncington Harbor, Norrhport Harbor, Port Jefferson, and Matti~uek Inla~. 5.8 Limit potential loss of life and structural ~-mnge in all development in the coastal area. Comply with the provisions of any municipal erosion management plan, con- sistent with the provisions of this policy. Construct buildings to meet applicable FEMA and New York State Uniform Building and Fire Protection Code standards. 1. Minimize additional hazards caused by storm-driven debris resulting from damage to buildings and other structures; A-10