under given conditions. Therefore before any model tests are undertaken 

 of proposed improvement plans, it is essential that the required simili- 

 tude is first established between the model and prototype and that all 

 significant scale relationships between the two are determined. 



Verification of a fixed-bed estuary model is generally accomplished 

 in three phases: (a) Hydraulic verification, which ensures that tidal 

 elevations and times, and current velocities and directions are in proper 

 agreement with the prototype; (b) salinity verification, which ensures 

 that salinity phenomena in the model correspond to those of the prototype 

 for similar conditions of tide, ocean salinity, and freshwater inflow; 

 and (c) fixed-bed shoaling verification, which assures acceptable repro- 

 duction of prototype shoaling distribution. In addition, dye-dispersion 

 verification is accomplished if the results of a prototype dye-tracer 

 study are available. 



Since discrepancies between model and prototype observations are 

 likely, the effects of various plans tested in the model on the basis 

 of model-to-prototype comparisons should not be evaluated. Therefore, 

 after the model has been verified, a series of observations is made 

 throughout the model to define "existing" or "base" conditions in the 

 model. The plan test results are then evaluated on the basis of model- 

 to-model comparisons to determine the changes caused by the plan. 



a. Tides . . The objective of the model tidal adjustment is to obtain 

 an accurate reproduction of prototype tidal elevations and phases through- 

 out the model. Prototype tidal data from several gages located throughout 

 the length of the estuary are required. The prototype tide gages must 

 have been operated continuously throughout the velocity, salinity, and 

 dye-tracer surveys. 



Because of limitations on the availability of personnel and equipment, 

 most prototype current and salinity surveys are conducted over a period of 

 several consecutive days, rather than obtaining all data simultaneously in 

 a single day. Therefore, during a prototype survey there can be signifi- 

 cant variations of tidal range. To avoid the time-consuming and expensive 

 procedure of adjusting a model to reproduce all of the tides during the 

 prototype metering program, a single tide is usually selected which 

 approximates an average tidal condition for the metering period; the 

 model is then adjusted for reproduction of tides, currents, and salin- 

 ities (for that metering period) for only the single tide. Verification 

 using tidal constituents is discussed in Section VII. 



With the model operated with freshwater only (saltwater is not required 

 at this stage), the primary tide generator is adjusted so that the tide 

 generated in the ocean causes an accurate reproduction of the prototype 

 tide at the control tide gage (located in the ocean or near the mouth of 

 the estuary). The appropriate freshwater inflovfs are reproduced in all 

 tributaries to the estuary during the verification process. The second- 

 ary tide generator (if used) and the model roughness are then progres- 

 sively adjusted until the prototype tidal elevations and phases are re- 

 produced to scale throughout the model. This adjustment is aimed at 



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