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<br />General Description <br /> <br />Subbasin or watershed hydrologic parameters that might be used as input to <br />rainfall-runoff models or other analytical techniques can be determined from <br />the HYDPAR program. At present the parameters that can be generated are, <br />(1) those needed for the U.S. Soil Conservation Service (SCS) Curve Number <br />(CN) technique and (2) those needed for watershed modeling using subbasin <br />imperviousness and characteristics of the Snyder unit hydrograph procedure. <br />The hydrologic parameters that are computed with the aid of a grid cell data <br />bank may be used conventionally (as manual input) or they may be automati- <br />cally input into a rainfall-runoff computer program such as HEC-l (U.S. Army <br />Corps of Engineers, 1973). <br /> <br />. <br /> <br />Input Limitations. The limitation on input data to the HYDPAR program <br /> <br /> <br />is defined through the use of a dynamic array. The variable names of the <br /> <br /> <br />input categories are given below, as well as the expression needed to compute <br /> <br />the maximum index value of that array. <br /> <br />Input <br />Number of Subbasins <br />NlDDber of Land Use Categories <br />Number of Slope Categories (SCS type) <br />Number of Data Variables in the GridC81l Data Bank <br /> <br />Variable <br /> <br />NSUB <br />NLUSE <br />NSLP <br />NVAR <br /> <br />y = (16 * NSUB) + (10 * NLUSE) + 5(NSUB * NLUSE) + NVAR + NSLP <br />y cannot exceed 131,000 <br /> <br />(3-1) <br /> <br />Hardware and Software Requirements. The HYDPAR program was developed <br /> <br /> <br />using a CDC 7600 computer at the Lawrence Berkeley Laboratory, University <br /> <br />of California, Berkeley, California. In general it is compabible with other <br /> <br /> <br />major computer systems. (Difficulties in installation should be reported <br /> <br />to the Hydrologic Engineering Center). <br /> <br />3-2 <br />