Sediment budget studies have been presented by Johnson (1959), Bowen 

 and Inman (1966), Vallianos (1970), Pierce (1969), and Caldwell (1966). 



4.712 Elements of Sediment Budget . Any process that increases the 

 quantity of sand in a defined control volume is called a sauroe. Any 

 process that decreases the quantity of sand in the control volume is 

 called a sink. Usually, sources are identified as positive and sinks 

 as negative. Some processes (longshore transport is the most important) 

 function both as source and sink for the control volume, and these are 

 called conveoting processes. 



Point sources or point sinks are sources or sinks that add or sub- 

 tract sand across a limited part of a control volume boundary. A tidal 

 inlet often functions as a point sink. Point sources or sinks are gener- 

 ally measured in units of volume per year. 



Line sources or tine sinks are sources or sinks that add or subtract 

 sand across an extended segment of a control volume boundary. Wind trans- 

 port landward from the beaches of a low barrier island is a line sink for 

 the ocean beach. Line sources or sinks are generally measured in units of 

 volume per year per lonit length of shoreline. To compute the total effect 

 of a line source or sink, it is necessary to multiply this quantity by the 

 total length of shoreline over which the line source or sink operates. 



The following conventions are used for elements of the sediment 

 budget: 



Q^ is a point source 

 Q^ is a point sink 

 q^ is a line source 



q^ is a line sink 



These subscripted elements of the sediment budget are identified by name 

 in Table 4-13 according to whether the element makes a point or line con- 

 tribution to the littoral zone, and according to the boundary across which 

 the contribution enters or leaves. Each of the elements is discussed in 

 following sections. 



The length of shoreline over which a line source is active is in- 

 dicated by hi and the total contribution of the line source or line 



*+ * — 



sink by Q^ or Q^ , so that in general 



Q* = b,. q,. . (4-46) 



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