Table 9 



Estimated Annual Average Winds (1940-1959) 



Direction 



Percent of Time 



N 



10 



NE 



9 



E 



9 



SE 



6 



S 



9 



SW 



22 



W 



17 



NW 



17 



Calm 



1 



Waves 



Waves that occur in the study area consist of sea- and swell-type waves. Locally generated 

 waves, generally referred to as seas, are typically observed as traveling with the wind. Swells are 

 waves generated from distant storms that enter the study area independent of the local wind 

 conditions. 



Visual surf observations were collected from the western end of Jones Beach (97 km 

 southwest of Shinnecock Inlet) for the period October 1954 to December 1957 under a cooper- 

 ative surf observation program between the U.S. Coast Guard and the Beach Erosion Board. 

 Results show that 98 percent of the waves were from the southern quadrant and the remaining 

 2 percent are from the east. The waves from the southeast and southwest predominated, with 41 

 and 40 percent of all waves coming from these directions, respectively. During the period of 

 observation, only 5 percent of the waves had a height of 1.2 m or greater (USAE District, New 

 York 1988). 



Wave data statistics were obtained from the WIS Atlantic Update - 1976 to 1993 (with 

 hurricanes) for Station 78 approximately 10.5 km south of Shinnecock Inlet at a depth of 27 m 

 (Brooks and Brandon 1995). The data consist of percent occurrence of significant wave heights 

 and period ranges in 30-deg angles of approach increments over an 18-year hindcast period (for 

 both storm and nonstorm conditions). Approximately 37 percent of the waves approach from 

 azimuths (56 to 146 deg) east of shore normal (158 deg). Thirty-two percent of the waves 

 approach from the western azimuths (169 to 259 deg). The predominant (15.3 percent) period is 

 between 7.0 and 7.9 sec, though all of the wave period bands between the 4.0- to 4.9-sec and 9.0- 

 to 9.9-sec bands have occurrences between 10.0 and 12.8 percent. The predominant (35.3 

 percent) significant wave height (in 27 m of water) is between 0.5 and 1.0 m (Brooks and 

 Brandon 1995). 



Chapter 3 Physical and Coastal Processes 



35 



