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<br />001989 <br /> <br />Typically, diversions below the San Juan basin reservoirs consist of a combination of natural flow <br />water rights and project storage rights. In practice, project water users in Colorado forgo their <br />natural flow rights which are stored for later use (Conversations with district engineer and operating <br />personnel). There are hundreds of diversions in San Juan River basin so no attempt was made to <br />model individual diversions except for major structures. Instead, aggregates of diversions were <br />modeled. Due to the use of aggregates, monthly time steps, and modeling limitations, no attempt was <br />made to differentiate natural flow right and project water right demands. Reservoir releases were <br />calculated based on downstream demands from a user specified sets of aggregate diversions. This <br />calculation also accounts for the availability of return flows, gains, and imports. <br /> <br />PreProcessor - Monthly Consumption and Demand Calculator <br /> <br />The need for the preprocessor was described in Chapter 3. Chapter 2 discusses the various depletion <br />mapped or proportioned to RiverWare nodes. These include irrigation and several non-irrigation <br />categories used in the natural flow analysis. Many of the files contained data obtained from other <br />sources such CRSCU&L files. All canal flows required for subbasin diversions were obtained from <br />Colorado in database format (dbf files). The Colorado data set was only available in digital format <br />since 1974. The 1970 through 1974 data were entered by hand into diversion spreadsheets from <br />paper records. <br /> <br />The following equations show how the pre-processor proportions the spatially tabulated HUC and <br />Unit depletion data into RiverWare node diversion and depletion requests. Most of the terms used <br />are discussed in Chapter 3. Three new terms are introduced: HUC combination, depletion <br />percentage, and HUC percentage. Discussion of these terms follows the equations. <br /> <br />Colorado Non Irrigation Depletion Request = <br /> <br />munb.,. of NonIr HUe COmbinati01U <br />I Dep/etionPercentage(i) * HUCDep/etion(j) <br />i=l <br /> <br />where <br /> <br />j is the non irrigation depletion category of HUC combination I and <br />DepeltionPercentage is percent of HUC category depletion apportioned to /, <br /> <br />New Mexico Non Irrigation Depletion Request = <br /> <br />number of NonfT HUe Combinations <br />L Dep/etionPercentage(i) * UnitDepletion(j) <br />i""l <br /> <br />where <br /> <br />j is non irrigation depletion category of HUC combination I and DepeltionPercentage <br />is percent of HUC category depletion apportioned to I. <br /> <br />DRAFT - SJRIP Hydrology Model Documentation <br />June 18, 1999 <br /> <br />50 <br />