In the years following World War II, Long Island experienced a building boom that saw ever-increasing numbers of new residents, many settling in coastal areas. This boom took place before the enactment of any National Flood Insurance Program (NFIP) restrictions on floodplain development. Consequently, much of this development occurred in areas that were later mapped as flood hazard areas. Suffolk County's estimated population (2000 US Census) now stands at nearly five times its 1950 level. Over this same 50-year period, there has been a nine-inch rise in relative sea level. This combination of events has contributed to repeated property damage from storms of both extra-tropical (northeasters) and tropical origin. Elevated tides and waves associated with these storms cause extensive flooding and erosion in the project study area.
Hurricanes are the most powerful tropical storms to reach the New York area with wind speeds in excess of 74 mph. Records are available for 24 hurricanes that have affected the New York area in the past century. The heaviest storm damage usually occurs when high astronomical tides and storm surge coincide.
Extratropical storms also affect the study area. While extratropical storms or northeasters are usually less intense than hurricanes, they tend to have a much longer duration and cover larger areas. Often lasting for a period of days, these storms persist through several periods of high astronomical tide. The long duration of extratropical storms greatly enhances their ability to cause damage. During the passage of a major extratropical or tropical storm, a temporary rise in water level is often generated, creating a storm surge. Rising water levels are also evident as propagating waves break near the coast in a process called wave setup. Historically, the combined effects of storm surge and wave setup with astronomical tides have caused extreme water levels in the study area which, in turn, have lead to severe property damage on both barrier island and mainland areas.
One example of a major storm is the hurricane of September 21, 1938, which caused severe damage on both the barrier island and mainland areas. Between Fire Island Inlet and Montauk Point, large areas were inundated, causing extensive damage. Over 700 homes on Fire Island were damaged, while nearly 300 were destroyed. Twelve new inlets, including Shinnecock Inlet, were formed along the south shore barrier beaches. Twenty square miles of the mainland were inundated as storm tides overtopped Fire Island. The low density of mainland development at that time resulted in minimal damages. However, a recurrence of these flood stages under today's level of development would flood approximately 8,500 mainland structures up to 6 feet in depth.
Another example of the storm damage problem is the extratropical storm of March 6, 1962. A total of 50 washovers occurred, and one new inlet at Westhampton Beach was formed. On Fire Island, a total of 47 homes were destroyed and 75 were damaged. Twelve square miles of the mainland were inundated; under current development conditions, a recurrence of these flood stages would mean that approximately 4,500 structures would be inundated up to 6 feet in depth. As a result of this storm, the New York District of the Army Corps constructed emergency protective works throughout the study area ("Operation Five-High"). Assistance was provided to the local communities in the removal of debris, and in the rebuilding of beaches and dunes. One of the first response actions of the Corps was to assist in the closure of the breach at Westhampton. In total, over 2 million cubic yards of material were used to rebuild over 23 miles of beaches and dunes in the study area.
Many severe storm events have impacted the study area in just the last decade. Events in September 1991, December 1992, November 1996, September 1999 have led to federal disaster declarations for Suffolk County. These four storms caused over $14 million dollars in damages to public infrastructure alone. The historic trends of increasing coastal development and sea-level rise have contributed to Suffolk County's current storm damage problem. Over the next 50 years, sea levels are forecast to continue rising, resulting in more frequent and severe storm damage. Given this combination of factors, the storm damage problem in Suffolk County is expected to intensify.
For more information please read the Fire Island Inlet to Montauk Point Project Fact Sheet or email the Project Manager.