Hydrological Responses Of Land Use/Land Cover Change In Huangshui River Basin, In Northestern Qinghai

In recent years, land use and cover change in regional scale attracts more and more extensive attention, and hydrological effects, as one of important environmental effects caused by land use and cover change, has become a research focus. For some region, we study the relationship between the land use and cover change and hydrological changes based on hydrological model and propose strategies of the environmental effects for the region.Huangshui River Basin is selected as the study area in this paper. The spatial database is built based on GIS and RS technology including the DEM, the land use and cover map and the soil type map. The attribute database includes parameters of land use and cover, soil and meteorological. The runoff change in Huangshui River Basin in recent 14 years is studied using the SWAT distributed hydrological model.According to DEM, Huangshui River Basin is divided into 37 sub-basins. The land use and cover, soil and slope classification threshold is set to 0% to analyze land use and cover change on runoff, and 3242 HRU is produced. Annual runoff is simulated from 1987 to 2000, and the sensitivities of water balance parameters are analyzed, and the model is calibrated with sensitivity parameters. Annual and monthly runoff are simulated from 1987 to 2000 and results are validated, found that NS>0.5 and R2>0.6, and shows that the good applicability of SWAT model is in Huangshui River Basin and SWAT can be a very good summary of hydrological processes, in particular runoff simulation.In the first, the production capacity of the flow of the various land use and cover type is analyzed using SWAT model by selecting a sub-basin, and show that the capacities of AGRC (infield), BARE(umemployed land), URHD (urban land), URMD (rural residential area) and UIDU (mining and transport land) are larger. With respective 1987 and 2000 land use and cover change data, mean annual runoff has increased, because infield and grassland convert to other types and these changes increase runoff, and mean annual water yield increases 130.65×10~4m~3 in 14 years; This paper designs a variety of scenarios, including land use and cover change and climate variability scenarios. The results show that runoff has been respectively reduced 60.8×10~4m~3, 132.9×10~4m~3, 493.3×10~4m~3 and 653.3×10~4m~3 in four scenes returning farmland to forest and grassland; climate fluctuations scenarios are simulated and results show that the changes of temperature and precipitation are very significant to runoff; by maintaining a constant factor, the effects on runoff are quantitatively distinguished between the climate fluctuation and land use and cover change, and it is obtained that the climate fluctuation is the primary driving force on the runoff change, and land use and cover change on the impact of runoff is very small form 1987 to 2000.