^3(3) " ^3,4) ■*" ^2 ^n (2,3) 



*+ 

 3(3) 



*+ 



Q , . = 305,000 + 58,700 cubic meters per year - 



217,500 cubic meters per year 



*+ 

 Q_^-v = 146,200 cubic meters per year (191,200 cubic yards 



per year) 



The after-inlet sand budget is shown in Figure 4-50c. 



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" 



+ *+ *+ 



Qo/oN = Qoz-o-) after inlet - Qo/o-v before inlet 



Q-^~. = 146,200 cubic meters per year - 62,700 cubic 



meters per year 



Q_._x = 83,500 cubic meters per year (109,000 cubic 



^3(3) 



yards per year) 



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

 nourishment of 146,200 cubic meters per year. 



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

 VIII. ENGINEERING STUDY OF LITTORAL PROCESSES 



This section demonstrates the use of Chapter 4 in the engineering study of 

 littoral processes. 



1. Office Study . 



The first step in the office phase of an engineering study of littoral 

 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 requirements of the owner or local 

 interests. For example, local interests may require a recreational beach in 

 an area of limited sand, making it necessary 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 littoral 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. 



4-133 



