Integration of geographic information systems and simulation model for watershed management

Simulation models are powerful tools in support of watershed analysis and assessment of management scenarios at the watershed scale. This paper integrates geographic information systems (GIS) and agricultural nonpoint source pollution model (AGNPS) to analyze the effect of land use change on nonpoint source pollution in a study watershed. ArcView nonpoint source pollution modeling (AVNPSM), an interface between ArcView GIS and AGNPS is developed to facilitate agricultural watershed modeling. The interface consists of six modules: a parameter generator, input file processor, model executor, output visualizer, statistical analyzer, and land use simulator. The interface requires input databases of soil, climate, digital elevation model, land use/cover, hydrography, and management practices. It was applied to study the watershed to simulate the impact of land use change on runoff, sediment, and nutrient yields based on a 25-year, 24-h period of single storm event of 114 mm. The simulation results show that expansion of urban land is likely to lead to an increase in surface runoff, peak flow, and soil erosion. The magnitude of the effect is related to the extent and proximity of proposed land use change to water bodies in the watershed.