b. Type 2 . Values of velocity as a function of time are tabulated 

 in the input file. 



c. Type 3 . An equation relating initial bay area, initial eleva- 

 tion in the bay, and elevation in the channel is specified at 

 the boundary. 



d. Type 4 . Values of discharge as a function of time are tabulat- 

 ed in the input file. 



e. Type 5 . The water surface elevation as a function of time is 

 described by a formula, e.g., a sine wave. A sine wave re- 

 quires two parameters, the wave amplitude and the wave period. 



94. For every external boundary node, a tabulation of time -dependent 

 input data is needed. Tabulated values are ignored if the boundary type is 

 Type 5, that is, if a formula describes the water surface elevation as a 

 function of time. For boundary Types 1 and 2, values of water surface 

 elevation and velocity as functions of time must be tabulated. 



95. In boundary Type 3, an equation involving two parameters is used to 

 relate the flow rate in the inlet channel to the bay water elevation. The 

 parameters are given as values of the variables DESCl and DESC2 (for example, 

 DESCl as the bay area and DESC2 as the difference in water surface elevation 

 between the channel and the bay). In many applications involving rivers, 

 discharge data will be available, and this situation is described by a Type 4 

 boundary condition. In boundary Type 5, values of wave amplitude and wave 

 period are entered as DESCl and DESC2 . 



96. Internal boundaries . Internal boundaries are specified at junc- 

 tions. However, DYNLETl handles this automatically. The model determines how 

 the junction nodes are located with respect to the channels and applies the 

 conservation of mass and momentum at the nodes. 



Nodal parameters 



97. Nodal parameters are values of variables assigned to an entire 

 channel cross section and consist of: 



a. Reference elevation. 



b. Lateral inflow rate. 



c. Channel alignment angle. 



d. Transition loss coefficients. 



e. Initial values of water surface elevation. 



f. Initial values of volume flow rate. 



38 



