GIS-BASED COUPLING OF GLEAMS AND REMM HYDROLOGY: I. DEVELOPMENT AND SENSITIVITY

Abstract

Movement of water from agricultural fields and into adjacent riparian areas is an important process inminimizing pollution for a large percentage of agricultural lands. Models have been developed for upland agriculturalareas and for riparian zones. Creating a flexible structure for linking two different models is both desirable and neededfor complete analysis of the systems. Since water is the primary mechanism for pollutant transport, creating a systemwhich manages both surface and subsurface water movement is a first priority. An integrated model system wasdeveloped for joining the hydrologic portions of GLEAMS and REMM in a cascaded format to determine the fate ofsurface and subsurface water leaving an upland cultivated area and traversing a riparian forest. Data was managedwithin a GIS to aid in inputting and manipulating both spatial and nonspatial model parameters. Transfer of subsurfaceflow from the upland model to the riparian model was achieved through Darcys equation. Partitioning of the flow wasbased on the hydraulic conductivity of the different layers and the depth of the water table. The model system was able toaccount for saturated zones encountered in the riparian area by raising the water table. The model system responded aswould be expected under relatively extreme changes in precipitation for both shallow groundwater levels and runoff. Themodel system also exhibited expected behavior under different leaf area index (LAI) parameters within the forest. Theshallow groundwater levels and runoff were not drastically affected, but the levels of response were within the range ofexpectations.