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<br />~~: 'flfl~Ol5' <br /> <br />lntroduction <br /> <br />Summary <br /> <br />1.4.14 Model Use and Testin!!: HYDROSS has been in use since 1978 and is widely <br />accepted as a river system operations model. HYDROSS has been extensively tested and has <br />undergone modification and refinement to provide reliable and credible results. <br /> <br />1.4.15 Outout Capability: The PC version of the HYDROSS model has the capability <br />to output results into fixed format text files (that can be printed to a wide carriage printer) and/or a <br />"Comma and Quotes" file (which can be loaded into graphics producing software, such as a <br />spreadsheet or database). <br /> <br />1.5 Data <br />HYDROSS operates on three functionally distinct types of data: Flow, Table, and Network <br />data. Detailed functional descriptions of the data components, file structures and record definitions <br />are covered in later sections of this manual. <br /> <br />1.5.1 Flow: Conceptually, the flow data is the pristine monthly flow at gaging <br />stations. In practice, the gaging station flow for a given historical period will include the effect of <br />any man-made improvements existing at the time, and someone has to work backward to decide what <br />the pristine flow would have been. Obtaining this flow data is outside the scope of this document. <br />The required format for the data is detailed in Appendix B.l [Page 37J. <br />HYDROSS assumes that the data in the Flow File is the pristine flow, and the model requires <br />flow data for each month of the study period at each station in the model. Station gain (or loss) is <br />calculated from this file as the downstream minus the upstream value. <br /> <br />1.5.2 Tables: The Table File is the mechanism for introducing operational parameters <br />to the model. The two types of tables are monthly (type 0) and parameter/function (type 1). The <br />structure and format of the Table File is detailed in Appendix B.3 [Page 39]. <br />Monthly tables contain data which are constant for a given month, but may vary month to <br />month and year to year. Each table record represents one year, and requires twelve entries (one for <br />each month). Tables may be fIxed (one table record for the entire study) or staged (a different table <br />record for each year). For example, crop irrigation requirements and reservoir evaporation rates are <br />defined in staged tables. <br />For staged tables, HYDROSS uses the latest table at or before the year under consideration, <br />and you do not need to have a table for each year of the study. That is, given only a table for 1953 <br />and for 1960, HYDROSS will use the 1953 table for the years 1953 through 1959, and then pick up <br />the 1960 table. <br />Parameter/function tables occur in pairs, and define a relation between a function value and a <br />(variable) parameter value. For example, reservoir elevation as a function of the reservoir content is <br />given in a parameter/function table. These tables require at least two entries, not exceeding 99 <br />entries. HYDROSS performs linear interpolation to derive a function value for a given parameter <br />value. <br /> <br />Parameter/function tables may also be staged. <br /> <br />Page 4 <br /> <br />HYDROSS 4.1 <br /> <br />March 25, 1991 <br />