Influence of tidal inlets on salinity and related phenomena in estuaries




Shankar, N.J.

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University of Texas at Austin


This study presents mathematical hydrodynamic and salinity transport models applicable to the analysis of the effects of tidal inlets on bays and estuaries having the typical morphology encountered in the U.S. coastal regions of the Gulf of Mexico. The practical utility of these models has been developed and demonstrated for the following specific cases: 1. Simulation of tidal hydrodynamics and salinity distributions under well-mixed water conditions for two bays on the Texas Gulf coast. 2. Analysis of the effects of altering natural tidal inlets on estuary-Gulf water exchange and on salinity concentration, transport and distribution. Analyses were conducted on both idealized and real estuaries. 3. Simulation and analysis of hypothetical shell reef removal. Specifically, Matagorda Bay, Texas, was used to verify both the tidal hydrodynamic model and the salinity distribution model. Galveston Bay, Texas, was used to demonstrate the effects of altering the size of a tidal inlet on water interchange and salinity distribution. Using computed baseline conditions for low and intermediate freshwater inflows to Galveston Bay, the assumption was made that an improved, continuously open tidal inlet was created at Rollover Pass into the Galveston Bay system. Changes in salinities, salinity gradients, Gulf inflows, tidal prisms, and circulation were computed for intermediate and low freshwater inflows. In addition, the effects of hypothetical removal of large shell reefs on circulation and salinity distributions were determined. Computations were made of water exchange across selected ranges within Galveston Bay under the various physiographic changes and estimates were made of the exchange ratios for different segments of the bay.


149 pgs.


inflow, salinity gradients, water analysis, water circulation, mathematical models