( 14 September 1969) 

 Figure 4-58. Fire Island Inlet, New York: overlapping offset. 



where waves from the updrift side dominate longshore transport. Where waves 

 from the updrift side are less dominant, the updrift offset (Fig. 4-57) is 

 common. Where waves approach equally from both sides, inlets typically have 

 negligible offset (see Fig. 4-59). Where the supply of littoral drift on the 

 updrift side is limited and the coast is fairly well exposed, a noticeable 

 downdrift offset is common as, for example, in southern New Jersey and 

 southern Delmarva (see Hayes, Goldsmith, and Hobbs, 1970). These planform 

 relations to littoral processes have been found for inlets through sandy 

 barrier islands, but they do not necessarily hold at inlets with rocky 

 boundaries. The relations hold regionally, but temporary local departures due 

 to inlet migration may occur. 



2. Field Study . 



A field study of the problem area is usually necessary to obtain types of 

 data not found in the office study, to supplement incomplete data, and to 

 serve as a check on the preliminary interpretation and correlations made from 

 the office data. Information on coastal processes may be obtained from wave 

 gage data and visual observations, sediment sampling, topographic and 

 bathymetric surveys, tracer programs, and observation of effects of natural 

 and manmade structures. 



a. 

 data. 



Wave Data Collection 



A wave-gaging program yields height and period 

 observations may currently be the best source of 



However, visual 



breaker direction data. Thompson and Harris (1972) determined that 1 year of 

 wave-gage records provides a reliable estimate of the wave height frequency 



4-142 



