of elements in the sand budget varies with locality and with the bound- 

 aries of the particular littoral control volume. (These elements are 

 classified as point or line sources or sinks in Table 4-13, and the budget 

 is summarized in Equation 4-48.) 



LAND 



Cliff, Dune and 

 Backshore Erosion 



Beach Replenishment 



Rivers 



Dune and Backshore 

 Storage 



Winds 

 (supply and deflation) 



Inlets and Lagoons 

 Including Overwash 



Mining 



OCEAN 



Offshore Slope 

 (source or sink?) 



Submarine Canyon 



Dredging 



Calcium Carbonate 

 (production and loss) 



Longshore Currents 

 Tidal Currents 

 Longshore Winds 



Figure 4-49. Materials Budget for the Littoral Zone 



In most localities, the gross longshore transport rate significantly 

 exceeds other volume rates in the sediment budget, but if the beach is 

 approximately in equilibrium, this may not be easily noticed. 



The erosion of beaches and cliffs and river contributions are the 

 principal known natural sources of beach sand in most localities. Inlets, 



4-132 



