The Application Of SWAT Model For Small Watershed Hydrological Response To Climate Change And Land Use Change

This study selects two typical small watershed which is located in the east and west sides of Miyun Reservoir respectively. Collect relevant data to establish the SWAT model databases, and construct Watershed SWAT model, run the model sensitivity analysis, calibration and verification. In the monthly scale evaluate model accuracy using the relative error (Re), the coefficient of determination (R2) and the Nash coefficient (Ens) and in the dailly scale evaluate the model accuracy by the correlation coefficient R2.Finally, from the perspective of water resources management debate the hydrological response to 1 climate change and use change.The SWAT model sensitivity analysis results show that the types of sensitive parameters are similar between the Tumenxigou watershed and Maoshigou watershed, but different catchments have different sensitivity of each parameter. Tumenxigou watershed is abundant in soil water, the parameters, like SOL_AWC, SOL_Z, affecting soil water are main sensitivity parameters. By contrast, the Maoshigou watershed is rich in groundwater, lateral flow, so parameters ALPHA_BF, HRU SLP are more sensitive.Calibrated simulation results show that the SWAT model is applicable to the Miyun Reservoir Area long time series of typical small watershed simulation and evaluation of water resources.The analysis of the Maoshigou watershed simulations under the assumed climate programs show that the yearly average runoff with increasing temperature is reduced, and the rate of decrease is small, when average temperature increases 1℃, runoff decreased by 1.1%. With the increase of precipitation growing, and the rate of increase is large, when average increase of 10% of precipitation, runoff increased 17.17%. With the reduction of precipitation, the runoff decrease but the rate decreased with the precipitation reduction is less than the increase with precipitation growing. In short the runoff is sensitive to precipitation changes, not sensitive to temperature changes. Coefficient of variation of annual runoff to climate change with changes in the range between 0.267-0.429; as temperatures rise, the annual runoff fluctuations in intensity will not change much and so on.The analysis of the extreme land use situations simulation in yearly scale shows that the forests have the largest water conservation ability while the grassland have the least, meanwhile the water consumption is also the largest while the grassland is the least,which the amount of available water resource is less than the shrub and the grassland.The analysis of the extreme land use situations simulation in monthly scale shows that the driving factor of forests conserving water have two aspects.On the one hand, increase dry season flow, on the other hand, reduce rainy season runoff, especially flood peak.