Nourishment needed to maintain historic erosion rate on Reach 3 beach 

 is: 



Reach 3 nourishment = Reach 3 erosion "after inlet" - Reach 3 erosion 

 "before inlet". 



^5(5) " \3) ('i'3i3)) after inlet - b^^^ (qj^^^) before inlet . 

 ^5(5) = 193,000 yd?/yr. - 82,000 yd?/yr. , 

 Qj^^^ = 11 1,000 yd?/yr. . 



If reach 3 erosion is to be eliminated, it will be necessary to provide 

 nourishment of 193,000 cubic yards per year. 



Q^, Qj^^, and Q^^ for the after-inlet condition are computed using 

 Equation 4-24 and related equations. The after-inlet sand budget is 

 shown in Figure 4-50c. 



************************************* 



4.8 ENGINEERING STUDY OF LITTORAL PROCESSES 



This section demonstrates the use of Chapter 4 in the engineering 

 study of littoral processes. 



4.81 OFFICE STUDY 



The first step in the office phase of an engineering study of litto- 

 ral processes is to define the problem in terms of littoral processes. 

 The problem may consist of several parts, especially if the interests of 

 local groups are in conflict. An ordering of the relative importance of 

 the different parts may be necessary, and a complete solution may not be 

 feasible. Usually, the problem will be stated in terms of the require- 

 ments of the owner or local interests. For example, local interests may 

 require a recreational beach in an area of limited sand, making it neces- 

 sary to estimate the potential rates of longshore and onshore-offshore 

 sand transport. Or a fishing community may desire a deeper channel in an 

 inlet through a barrier island, making it necessary to study those litto- 

 ral processes that will affect the stability and long-term navigability 

 of the inlet, as well as the effect of the improved inlet on neighboring 

 shores and the lagoon. 



4.811 Sources of Data . The next step is to collect pertinent data. If 

 the problem area is located on a U.S. coastline, the National Shoreline 

 Study may be consulted. This study can provide a general description of 

 the area, and may give some indication of the littoral processes occur- 

 ring in the vicinity of the problem area. 



4-139 



