When a basin enclosed with vertical sides has a well-defined major 

 axis and a gradually varying cross section, it is possible to use a 

 dynamic one-dimensional, computational model for evaluating fluctuations 

 in water level resulting from a forcing mechanism such as wind stress, 

 and also to account for some of the effects of a varying cross section. 

 The validity of such a model depends on the behavior of the storm system 

 and the geometric configuration of the basin. 



Equations 3-79 and 3-80, when the varying width b of the basin is 

 introduced, can be written in terms of the volume flow rate Q(x,t) as 



9Q 9S b , 



as _ 1 aq 



9t b dx 



(3-85) 



where x is taken along the major axis of the basin, and for any time t, 

 A is the cross-section area, and D is the average depth A/b or 

 D = d + S. 



Various schemes have been proposed for evaluating the water level 

 changes in an enclosed body of water by using the differential equations. 

 (Equations 3-84 and 3-85.) The formulation of the problem and the numer- 

 ical scheme given here is from Bodine, Herchenroder and Harris (1972) . 



The surface stress and bottom stress terms are taken identical to the 

 terms given for the quasi-static method for open-coast surge. (See 

 Equations 3-55 and 3-56, Section 3-865b(l) (a) .) The stress terms, in 

 terms of the volume flow rate, become 



(3-86) 



(3-87) 



Substituting Equations 3-86 and 3-87 into Equation 3-84 gives 



— = bkWW, - gA ^ - -^^ (3-88) 



3-131 



