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<br />,,' <br /> <br />001159 <br /> <br />22 <br /> <br />Equation 1 is termed the objective function; it represents the sum of costs over all arcs. <br />Equations 2 and 3 arc constraints. The lirst ,constraint insures that flow in any arc is always within the <br />capacity limits of that arc. The second constraint insures that combined inflows equal combined <br />outflows at each node, Le., that mass balance is preserved. <br /> <br />The core of CRAM consists of a central solution algorithm, ,he Out-of-KiI,er Algorithm (OKA), <br />which solves the linear problem stated generally above. The OKA is surrounded by a shell which acts as <br />a translator, converting the user input Iiles into a form amenable for solution by the OKA. <br /> <br />The program responds to arc characteristics: and relationships which are specified in the in'put <br />files. Arcs are used to represent stream reaches, pipelines, ditches and canals, reservoirs, demands, <br />water right decrees, target storage volumes, and inflows. For example, the capacity of a pipeline or limit <br />to a decree may be represented by-limiting the quantity of water allowed to pass through an arc. <br /> <br />CRAM makes it possible to represent many operating rules using arcs in the network. Water <br />allocation reflective of water rights priorities and operating rules is accomplished by placing relatively <br />higher values (or lower costs) on arcs which should preferentially receive allocations of water at any <br />given time step. For example, arcs representing more senior water rights or desired reservoir storage <br />levels are given higher values than junior rights or sto.rage in excess of the desired level. <br /> <br />The Central Resource Allocation Model adapts the Out. of-Kilter Algorithm to river basin and <br />water supply modeling. CRAM relies on three data input files: a network file, a data file and a template <br />file. The network file describes the basic configuration of the model network, i.e., the connection of <br />arcs and nodes as well as ranks or priorities on various arcs. The data file provides monthly flow <br />capacities, inflows, demands and other operating data for use during the model run. The template file <br />controls the model's output by regulating the amount of information to be stored in the binary file (an <br />information file that is created during each model run). In addition to the threc input files, the model <br />makes use of a utility called "CRAM Hooks" which allows for the linking to the model of special code to <br />represent specific operations such as flood control, power generation and return flows. <br /> <br />Configuration of the Yampa Basin Model <br /> <br />A diagram showing the current network configuration of the Yampa River Basin Model is <br />attached as Figure 4-2. The network takes a form similar to the drainage pattern of the basin with flow <br />in the network being generally from right to left. The network is comprised of six types of arcs and <br />elements: 1) nodes, 2) inflows (labelled "INFL"), 3) demands (labelled "DEMN"), 4) links (labelled "LINK" <br />or simply "L"), 5) decrees (labelled "DECR") and 6) reservoirs (labelled "RESY"). Each of these arc types <br />and elements is discussed below. <br /> <br />Nodes' <br /> <br />A node is a junction in the network representing a point of inflow, outflow (demand) or the <br />joining of different arcs. . . <br /> <br />Inflows <br /> <br />Inflow arcs introduce .water into the model network where it is allocated among vario~s <br />demands (including stcrage) on the basis of user-defined priorities. Water forced into the network in <br />excess of modeled demands is automatically rout~d downstream and out of the network. <br /> <br />. <br /> <br />,j!",i <br />