Decision support system for conjunctive stream-aquifer management

A decision support system (DSS) is presented for conjunctive management of surface water and ground water under prior appropriation. The DSS is constructed around the generalized river basin network how model MODSIM, providing an open architecture allowing access to input and output databases and modification and verification at all levels of the modeling process. The graphical user interface for the MODSIM DSS provides spatially referenced database capabilities whereby the user can create and link river-basin network objects on the display and populate and import data for that object interactively. Geographic information system tools are used to prepare grid-based spatial data for input into MODRSP, a modified version of the U.S. Geological Survey (USGS) three-dimensional finite-difference ground water model MODFLOW. Response functions generated by MODRSP are provided to MODSIM for simulating spatially varied and time-lagged return/depletion flows from stream-aquifer interactions. Capabilities of the MODSIM DSS are demonstrated on a case study for a portion of the Lower South Platte River Basin, Colorado. Results of the case study indicate significant differences between using ground water response coefficients developed from preassigned stream depletion factor (SDF) values, as currently used in the basin, and those generated using a finite-difference ground water model.