predicted with quantitative accuracy. The types of construction in 

 estuaries normally accomplished by the U.S. Army, Corps of Engineers, 

 include: 



(a) Construction of new channels or the deepening of 

 existing channels for navigation purposes; 



(b) construction of dikes, jetties, sediment traps, and 

 sand-bypassing facilities to alleviate sedimentation; 



(c) construction and operation of dams and reservoirs to 

 reduce flood damage and to resolve water supply problems; 



(d) dredging of new tidal inlets or the stabilization 

 and improvement of existing inlets for small-craft or deep- 

 draft navigation; and 



(e) construction and operation, of barriers for control of 

 flooding by storm surges (U.S. Army Engineer Waterways Experi- 

 ment Station, 1969). 



Various aspects of fixed-bed models of estuaries are discussed later 

 in this section, with emphasis on practices used at WES. Since most 

 movable-bed model studies of estuaries are confined to the immediate 

 entrance area, this type of model is discussed in Section VII. 



2. Model Design Considerations . 



a. Similitude Relations . Since gravitational forces are predominant 

 in tidal flows, it can be demonstrated that the model and prototype Froude 

 numbers, F^^, must be equal. Therefore, using equation (2-9), 



m _ p 



Sm'^m Sp^ 



P P 



where V^/(gL) is the Froude number. For distorted-scale models, depth 

 is taken as the characteristic length; thus, 



V2 v2 



EL^ (3-1) 



(3-2) 



(gr(Lv)r) 



1/2 



This can also be shown by inspection of the pertinent differential 

 equation (also referred to as inspectional analysis). According to 



52 



