Laserfiche WebLink
<br />REGIONAL PLANNING POTENTIAL OF <br />DETERMINISTIC HYDROLOGIC SIMULATION MODELS <br /> <br />Comment, Mr. Thomas: Your allegations about no predictive model being <br />available are unfounded. I suggest that WES become familiar with <br />several computer programs that are available, in particular the <br />SSARR model of North Pacific Division. <br /> <br />Reply, Mr. Benn: The WES, in its efforts to assess the environmental <br />constraints or impacts on both military and civil activities, has <br />recognized the need for large-scale simulation of virtually all of <br />the processes in the hydrologic cycle. <br /> <br />For example, procedures for estimating soil trafficability require an <br />accurate estimate of soil moisture with depth for very specific locations. <br />I emphasize specific locations because the vast majority of the world's <br />soils does not present a trafficability problem, but there is a traffica- <br />bility problem as a whole, because of the manner in which the relatively <br />few problem soils are distributed in the landscape. Recently the WES has <br />studied many of the existing hydrologic simulation models, including the <br />Kentucky, Stanford, USDA, USGS, Texas, Kansas, and the HEC hydrograph <br />package. All these models are optimized to reproduce storm hydrographs, <br />and a significant attribute of the models is the fact that they all use <br />"lumped" or watershed average values to estimate transpiration, intercep- <br />tion, water storage changes, infiltration, etc. Further, the specific <br />values for input functions are determined by forcing the predicted hydro- <br />graph to fit the measured hydrograph. This result is a calibration or <br />solution for a specific watershed with little assurance that the input <br />functions are related to the real world, or indeed even to each other, in <br />a unique way. I feel that practical improvements in the existing models <br />can be made by developing methods for simulating the various hydrologic <br />process as a function of specific measurable terrain parameters. This <br />would result in more suitable models for solving a wider range of Corps <br />of Engineers' problems in worldwide terrain conditions. <br /> <br />38 <br />