of n can be increased or decreased accordingly. IVhen the computer 

 model has been satisfactorily calibrated to predict inlet velocities, 

 predicted bay water levels should be checked against measurements to 

 assure that levels are being modeled correctly. If inlet velocities 

 are not available, bay levels can be used to calibrate the model. 



Step 9 . If additional prototype data are available, these data 

 should be used to verify that the model adequately predicts inlet and 

 bay hydraulics. 



Step 10 . At this point the computer program is ready to use for 

 prediction. Examples of the use of the computer program are presented 

 in the following section. Input and output data, and computations are 

 in U.S. Customary units. 



III. EXAMPLES OF C0f4PLITER PROGRAM PREDICTION 



1. Cabin Point Creek, Virginia . 



Cabin Point Creek is a shallow natural tidal inlet that connects a 

 bay to the lower Potomac River (Fig. 2) where the mean tidal range is 

 approximately 1.5 feet. 



In this example, the model was calibrated with prototype river and 

 bay levels and the calibrated model was then used to predict inlet veloc- 

 ities, discharge, and bay level for a second inlet added to the system. 

 The procedures for using the model are: 



(a) The inlet cross section was measured (Fig. 3) on 24 

 May 1976, and is assumed to be representative of the 1,900- 

 foot-long inlet. 



(b) The inlet is modeled using a grid system of three 

 channels and two identical cross sections (Fig. 3) at either 

 end of the inlet. 



(c) The bay area, A^, measured from a 7%-minute U.S. 

 Geological Survey (USGS) topographic map, was 3.5 x lo^ 

 square feet. For an increase in bay water elevation of 

 0.25 foot, the bay surface area increases approximately 5 

 percent because of marsh flooding. The bay area variation 

 parameter, 3, can be determined from this information 

 using equation (2), rearranged as: 



or, in this case. 



1 ( %ay 



(5) 



0.25 



(1.05 - 1) = 0.2 



