Table 8 



Shinnecock Inlet Tidal Prism (USAEWES 1995) 



Survey 



Tide Range' 

 m(ft) 



Tidal Prism 2 

 x10 7 m 3 (x10 8 ft 3 ) 



21-23 July 1992 



0.76 (2.5) 



2.43 (8.58) 



15 September 1993 



1.22(4.0) 



3.85 (13.6) 



20-21 July 1994 



1.16(3.8) 



3.31 (11.7) 



'Tide ranges determined from low water slack to high water slack based on NOAA tide tables, 

 ^idal prisms calculated based on the floodingj>hase of current measurements. 



Winds 



Wind velocities, duration, and direction determine the characteristics of waves likely to be 

 experienced in the study area. Wind-generated waves are the primary natural force which shapes 

 the ocean shoreline along the southern Long Island shore. The design height of most shore 

 structures is dictated to a great degree by the height of such waves. 



Wind records from the U.S. Coast Guard and Suffolk County Highway Department for the 

 south shore of Long Island for the period 1940 to 1959 were used to compile the percent- 

 occurrence of winds, by direction from which winds blew, as tabulated in Table 9. Wind data 

 were collected at the U.S. Coast Guard Stations at Tiana and Shinnecock and at the Suffolk 

 County Highway Department gauge at Westhampton Beach. The predominant onshore winds are 

 from the southwest. Winds from the eastern and southern quadrants, although infrequent, have 

 an appreciable influence on the south shore of Long Island due to the essentially unlimited open 

 ocean fetch length over which they are generated (USAE District, New York 1988). 



Evaluation of wind records from the U.S. Navy Hydrographic Office for the area near the 

 shore of Long Island indicate that winds from the westerly quadrants prevail, which is in agree- 

 ment with Table 9. Monthly cumulative average winds over the North Atlantic indicate that the 

 predominant direction of offshore surface winds is from the northwest for the period October to 

 April and from the southwest for the period May through September (USAE District, New York 

 1988). 



Over 50 percent of the winds which exceeded 17 m/s (33 knots) are from the west and 

 northwest. Approximately 20 percent of the winds from the southeast quadrant exceeded 

 17 m/sec (33 knots). Wind data extracted in the Wave Information Study (WIS) hindcast 

 (Brooks and Brandon 1995), while not directly applicable to the study area, represent the 

 offshore wind environment and indicate that the predominate wind speeds range from 2.5 to 12.5 

 m/sec (4.8 to 24 knots), totaling about 90 percent of all recorded wind speeds. Approximately 

 70 percent of all recorded wind records are less than 7.4 m/sec (14.3 knots) (Moffatt & Nichol 

 1996). 



34 Chapter 3 Physical and Coastal Processes 



