GIS-based coupling of GLEAMS and REMM. Hydrology: I. Development and sensitivity

Movement of water from agricultural fields and into adjacent riparian areas is an important process in minimizing pollution for a large percentage of agricultural lands. Models have been developed for upland agricultural area s and for riparian zones. Creating a flexible structure for linking two dif ferent models is both desirable and needed for complete analysis of the sys tems. Since water is the primary mechanism for pollutant transport, creatin g a system which manages both surface and subsurface water movement is a fi rst priority An integrated model system was developed for joining the hydro logic portions of GLEAMS and REMM in a cascaded format to determine the fat e of surface and subsurface water leaving an upland cultivated area and tra versing a riparian forest. Data was managed within a GIS to aid in inputtin g and manipulating both spatial and nonspatial model parameters. Transfer o f subsurface flow from the upland model to the riparian model was achieved through Darcy's equation. Partitioning of the flow was based on the hydraul ic conductivity of the different layers and the depth of the water table, T he model system was able to account for saturated zones encountered in the riparian area by raising the water table. The model system responded as wou ld be expected under relatively extreme changes in precipitation for both s hallow groundwater levels and runoff The model system also exhibited expect ed behavior under different leaf area index (LAI) parameters within the for est. The shallow groundwater levels and runoff were not drastically affecte d, but the levels of response were within the range of expectations.