Research Of Land Use Change And Its Impacts On Runoff In Mountain Area Of Shiyang River

Land Use and Land Cover Change (LUCC) is the hotspot and leading edge of global environmental change, the environmental effects of LUCC at the regional scale is paid increasingly widespread attention at home and abroad, especially the hydrological effects of LUCC, the hydrological effect of LUCC is listed as an important part of global environmental change.AS a vulnerable area of water resources and ecological environment in the arid areas in the Northwest, Shiyang River region is given a popular concern. Research of the LUCC and its impact on surface runoff is useful to know the variation and characteristics of water and soil resources, and it will provide scientific basis of water resources rational allocation and optimization for the basin.In the paper, with fiver sub-basin watershed of the river as study area, based on remote sensing images of 1977,1980,1994,2002,2009 year, land use data of the five times was obtained by image preprocessing and image interpretation, then the spatial and temporal scale changes in land use were analyzed. Based on runoff data of 1980-2008 year, using the method of correlation analysis, the impact on surface runoff of land use change was studied, the main conclusions are as follows:(1) The grassland and forest land are the dominant land type in study area, followed by unused land and water, with arable land and urban industrial land occupied. Land use has a fluctuation change trend, and land use change is the most significant and fastest in 1977-1980 years.(2)Forest land was mainly transformed into grassland; the maximum contribution of grassland to forest land is 23.05%. While grassland was mainly transformed into forestland and unused land, waters was mainly transformed into unused land. The upper basin of river was a sensitive area of land use change and the ecological degradation zone was formed, with Lengdongling as a center at the junction with three regions. The greatest space changes in land use occurred in 1977-1980 years, while the smallest changes occurred in 2002-2008 years.(3) Based on spatial scale, time scale and cell scale, the effects on surface runoff of land use change were studied, results showed:the correlation of certain types of land use change and surface runoff was not significant by lumped method, the correlation coefficient had abnormal values, it stated the correlation of land use change and surface runoff was distributed. In the study of cell, Nanying reservoir showed the opposite correlation coefficient, the study results revealed that glaciers and runoff, runoff coefficients were significant at 0.05 level, and glaciers were the main affect factors on surface runoff in Nanying reservoir.