The Application Of WEPP And GIS

Water erosion is one of the most important contributors of non-point source pollution. Human activity and landcover are among some most significant factors influence the severeness of water erosion. China is enhancing its environmental protection, and returning some erosion prone area from agriculture to forestry is one major step. In order to accurately and timely assess the effectiveness of management practices, mathematic models, especially distributed, physical-process based model in recent years, have become a power tool in to simulate the change and trend. However, due to the extreme complexity in natural system, the model need a great deal of data of various types, such as climate, soil, hydrology, geology, plant, topography etc. Normally a distributed-parameter model is not designed to handle such large quantity data. With the advance of information and computer technology, GIS has excellent advantages in processing spatial data and performing spatial analyses. This paper studies how to link GIS and WEPP, a Distributed-Parameter Model, together to simulate the erosion of Xiangyanggou, a 3.65 km2 watershed located 12 km from Yanan city.First, with Spatial Analyst of ArcGIS, the hydrologic analyses were conducted based on the DEM (digital elevation model). ArcGIS collected the data about the characteristic of topography, such as flow direction, stream networks, and created sub-watersheds. Also by using ArcGIS, a paper map showing the management measures of Xiangyanggou was converted to adigital form, and fed WEPP as the management layer. Then the meteorologic data were processed by BPCDG, and the soil data were collected from historical survey data. Finally, simulations were performed by WEPP with the input data mentioned above. By comparing with monitoring data, the simulated amounts of soil loss and runoff of Xiangyanggou indicted that the simulation of WEPP was reasonable, and proved some management could reduce the severeness of erosion. Meanwhile, GIS could provide data to WEPP effectively, and better illustrate the results from the simulation model.