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Once a model grid is developed, it is exported from GMS as a DXF format file (see Box 2 on <br />Figure 1) for import to program StateDGI (Box 7 on Figure 1). Layer elevations for each cell in <br />the model are exported to EXCEL and formatting changes are made manually to this table to <br />allow it to be imported to program StateDGI. <br />2.3 Model Dataset Development <br />After conceptual model elements are defined and the model grid developed, a series of data <br />management programs (DMIs) are utilized to prepare actual numerical model datasets. The <br />current process is data centered; however, it entails multiple sequential processing operations, <br />and is specific to the selected finite difference grid. Each of the major pre-processing steps <br />shown on Figures 1 and 2 are addressed in the following sections. <br />2.3.1 StateDGI Processing <br />The basic function of program StateDGI is to define all of the spatial components for flow- <br />related processes that occur within each individual model cell for use in subsequent processing <br />steps, where actual model control files are generated. Program StateDGI, which is the process in <br />Box 7 of Figure 1, consists of Avenue scripts that run within ArcView with the Spatial Analyst <br />extensions. Output files are created in ACCESS 97 and are translated to text files for use with <br />program StatePP (Box 8 on Figure 1). Program StateDGI operates using command files that <br />may be built within an integrated GUI module. Inputs to this process consist of a DXF file of the <br />computational grid exported from GMS, and an EXCEL file containing layer elevations exported <br />from GMS and reformatted for import to ArcView (Box 2, Figure 1). Spatial coverages from the <br />GIS repository are also used. Some of these coverages and processing steps are specific to the <br />RGDSS and may not be used in other model applications. <br />Information from GMS must initially be processed within program StateDGI to an appropriate <br />GIS coverage. This requires importing the grid and creating point elevation coverages for each <br />layer using the EXCEL import file. This only need be done once, since command files are <br />generated that can be modified later. In addition to the grid and elevation coverages, GIS <br />coverages must be available with appropriate fields for canals, irrigated lands, wells, permits, <br />native vegetation areas, and for external boundary flows that are not simulated using the general <br />head boundary condition. Modules within program StateDGI match wells to individual parcels, <br />assign wells to layers based on the specified screen interval and layer elevations at the well <br />location, and summarize all flow-related terms on a cell by cell basis for subsequent processing. <br />A series of eight files are generated by program StateDGI for subsequent processing in program <br />StatePP. The contents of these files are listed below. Note that most flow-related components <br />are accumulated by irrigation ditch (aka "structure"), since this is how data area organized from <br />the consumptive use process. <br />^ Canal length by cell for each irrigation ditch <br />^ Total irrigated area within each cell by irrigation ditch <br />