| A micro-computer based decision support system has been prepared for conjunctive stream-aquifer management under prior appropriation through a synthesis of existing technology rather than development of new models. A finite difference groundwater model (MODRSP) has been linked with a capacitated river basin network management model (MODSIM) using geographical information system (GIS) and database technology (DBMS).; The computer-aided design package, AUTOCAD, and a powerful, low-cost, raster GIS package, IDRISI, are used for preparing grid-based spatial data which is directly input into MODRSP, a modified version of the USGS three-dimensional finite difference groundwater model, MODFLOW, to generate numerical groundwater response coefficients. These response coefficients are used by MODSIM to simulate spatially varied and time-lagged stream-aquifer return/depletion flows.; The integration of GIS, DBMS, MODFLOW, and MODSIM allow analysis of conjunctive use plans which are capable of considering decreed flow and storage rights, river calls, exchanges, trades, and plans for augmentation. The groundwater hydrologic components modeled using MODSIM include reservoir seepage, irrigation infiltration, well pumping, and channel loss, channel routing, return flows, river depletion due to pumping, and aquifer storage.; A case study was carried out on a portion of the Lower South Platte River Basin, Colorado. A groundwater grid network was prepared using GIS techniques and response coefficients were generated using MODRSP. The coefficients were used in MODSIM to simulate an augmentation plan water right account. The effects of the augmentation plan on daily administration for a river regulated under prior appropriation water laws were simulated using MODSIM. Prototype user interfaces were prepared using the desktop mapping software, MapInfo, and the spreadsheet software, QUATTRO PRO, to demonstrate decision support system capabilities.; Computerized data available from databases maintained by the Colorado State Engineer (water rights, diversions, groundwater, stream flow); USGS (groundwater, digital line graphs, digital land use, digital elevation data, streamflow); and Bureau of Census (TIGER files) were used for the study. |
