Study On Water Environment Effect Of Water - Impermeable Surface Change In Dianchi Lake Basin

Since the 1979 reform and opening up, China’s urban rapid development of urbanization is accelerating, making China one of the world’s most rapid changes in land cover in the region. With rapid urbanization, urban construction land increasing, rapid expansion of impervious surfaces, the city has a high value of grasslands, wetlands, and other water sources dwindling, and brought demands for land and water resources in the city and a contradiction between supply.Increasing impervious surfaces, blocking the urban surface water into the city’s land surface soil, and even cut the link between urban surface and groundwater text, change the regional water cycle. Impervious surface coverage increases, increasing the volume and flow of surface runoff, so the lag time was significantly shortened, resulting in heavy rains accelerate time to peak. While a large number of contaminants can not be deposited in surface runoff erosion process, the absorption process by runoff into the receiving water body(such as rivers, lakes, straits, etc.), resulting in eutrophication and other forms of pollution of water bodies. Will increase impervious surface area make temperatures rise, changes in weather patterns and indirectly affect the watershed ecosystem biodiversity, increasing fragmentation of the number of river water and sediment basin natural landscape. Some works of measures, such as the transfer of the river, canals, dams, dredge pipe, etc. These practices may in the short term to solve some of the environmental problems of water column with the increase of impervious surfaces brought, but as time goes by They will only further damage the riverbed and riparian habitat(wetlands), but with the advent of intensive land use, resulting in a growing number of pollutants, and increased surface runoff makes more pollutants into the subject receiving water body, resulting in non-point source pollution, resulting in decreased water quality.In the past 20 years, with the development and construction of Kunming, the city gradually increased impervious table, due to surface runoff, erosion, along with a large number of pollutants import Dianchi Lake, Dianchi lead to deteriorating water quality. In this paper, Dianchi Lake Basin study area, the digital elevation model basin(DEM) data, divided according to the natural production in the basin of the river, the bus features the entire Dianchi Lake Basin designated as 17 sub-basins, analyze its impervious surface and river water quality response relationship between the threshold between the two to find out, to provide theoretical support for the management and protection of water quality-based urban planning Dianchi Lake.