Application of the opset version of the Stanford Watershed Model in an urbanizing Houston watershed



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The suitability of the Stanford Watershed Model in simulating streamflow in a Gulf Coast watershed was tested. The University of Kentucky "OPSET" version, (a self calibrating program determining the best sets of parameter values for the watershed), was utilized to synthesize a series of yearly streamflows in Sims Bayou, an urbanizing basin in the southern part of the Houston Metropolitan area. OPSET determines the best sets of parameters by averaging the yearly parameters for 5 or 10 years as required for the watershed and thus eliminates the tedious and more complex trial and error method of the Stanford Watershed Model. The Sims Bayou results were somewhat satisfactory but not to the extent expected. The methodology of improving the simulation process has been developed by further adjustment of the watershed parameters obtained by taking an average of the improved watershed parameters obtained from the Modified OPSET Method. Further testing of OPSET in the same watershed at an earlier date, when it was comparatively undeveloped, produced better simulation results indicating OPSET is more effective in a rural region than in an urbanized area. Test results also reflected the increased flood peak for storms with the increase of urbanization. Further work is necessary in separating the complex urbanized flow (and its diverted routing through the networks of the storm drainage system) from the natural flow routing of streamflow.