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water rights or reservoir drawdown targets). The solution of the network is the set of flows that <br />produces the minimum total cost (or maximum total value) for the entire network. The CRPM can be <br />thought of as a shell around the OKA solver which acts as a translator, converting the user input files <br />into a form amenable for solution by the OKA. <br />Application of CRAM to a river basin allows both simulation and optimization analysis. Pure <br />simulation can be achieved by constraining all flows through the network to a single flow value. <br />CRAM's optimization capabilities can be used by lifting some or all of these constraints. CRAM <br />and the solution of a network using the OKA ensure both continuity (conservation of mass) and <br />attaining an optimal network solution subject to the constraints imposed. <br />The CRAM system utilizes two periods, a repeating period which contains one or more sub-periods. <br />The repeating period might, for example, represent a year and the sub-period a month. However, <br />other interpretations of the two periods may be adopted so long as the input data and the periods are <br />consistent and the correct interpretation of the output is made. That is, CRAM has no way of <br />knowing if data supplied to it are on an annual, monthly or daily basis. <br />In the CRPM, the repeating periods are years. Each year is further broken down into 36 sub-periods. <br />These sub-periods represent time increments ranging from 8 to 11 days. Sub-periods were chosen in <br />order to generally correspond with months and allow more convenient manipulation and expression <br />of model input and output data. The sub-periods chosen for the CRPM are also convenient for <br />representing the manner in which the Division 3 Engineer administers the Rio Grande Compact. In <br />the following discussion, the repeating period will be termed a "year" and the sub-period a "season". <br />CRPM Model Characteristics <br />Network Representation of the Conejos River <br />A network representation of the Conejos River basin was developed for application to the general <br />CRAM solution algorithm. The network representation is contained within one of the model input <br />files. The network consists of the Conejos River from Platoro Reservoir to the Rio Grande River, <br />the Los Pinos and Rio San Antonio rivers between Ortiz and the confluence with the Conejos River <br />and all diversion ditches on these streams. The Conejos River network contains approximately <br />1,500 arcs, 8 inflows, 150 return inflows, and 120 demands. The actual computer input file defines <br />all connectivity of physical features. The user has access to this file and may modify some of its <br />features. A diagram of the network used to represent the Conejos River in the CRPM is provided as <br />Attachment 1. <br />Model Input Data Requirements <br />To run the CRPM, the user must supply several input files which contain data on hydrology, water <br />rights priorities, demand locations, and a variety of other information on physical features or <br />institutional system constraints. This information may be modified, within limits, by the model user <br />to define different model "scenarios." Additional information required to run the model is internally <br />coded and may not be changed by the model user. <br />Study Period and Model Time Steps <br />The model study period is defined by the length of the time series data contained within the input <br />data files. The study period length may be changed by the model user if desired. If longer model <br />runs are desired, additional information on inflow hydrology and forecasts must be developed. The <br />C:\cdss\Task3Mem.doc Review Previous Modeling Efforts Apri16, 1999 -Page 2 of 11 <br />