A Study On Watershed Geographic Characteristics For Weihe Basin Based On GIS

Based on digital geographic data, together with the integrated applying of Remote Sensing (RS), Geographic Information System (GIS), Global Positioning System (GPS), internet and other technologies, digital watershed is a platform and applying tool for information collection and storage, dynamic monitoring and integrated management for the watershed physical environment, infrastructure, natural resources, cultural landscape, ecological environment, population distribution, social and economic status and others, with the help of the visual information platform construction.Model construction, especially hydrological model construction is the core and foundation of "Digital watershed". At present, the Distributed Hydrological Model (DHM) is considered to be a popular hydrological sciences research, also is an important tool for hydrological research and practical problems solving. DHM bases on the mesh or sub-basin, and needs lots of process parameters, with the requirement of input data which can reflect the spatial heterogeneity of the hydrology sufficiently; so the demand for data acquisition is higher, while the conventional method is difficult to satisfy. The GIS can provide accurate and efficient data extraction and processing functions, with the capability of handling with different data sources such as maps, aerial photographs, which greatly facilitates the DHM.According to the spot investigation and analysis of the water quality of Weihe River, this paper covers on the DHM of Weihe Basin primarily. Based on the GIS technology, watershed geographic information analysis has been done by the integration of Arc/Info 8.3 version and ERDAS IMAGINE 8.6 version. Based on the one kilometer digital elevation model (DEM) database provided by USGS (Unite States Geological Survey), the river network was draw and watershed information was picked out for Weihe Basin, with the aid of spatial analysis and hydrologic analysis model for Arc Hydro extension of Arc/Info 8.3 version. The elevation values, flow accumulation area and other topographic data have been analyzed from DEM, for the datum provision of surface parameters of watershed DHM.As a means of space data acquisition, RS has become the principal source of information and data to update for GIS. According to the analysis of landsat satellite images, the landuse of Weihe Basin mainly divided into seven types as follows: urban areas, upland, irrigated cropland, shrubland, water, forest and grassland; classifated the main types of soil based on the global database of soil types and soil types classification system provided by FAO-UNESCO; and with the 1km NOAA/AVHRR database, analysised the watershed normalized deviation of vegetation index (NDVI).