Hydrological Responses To LUCC Based On SWAT Model In Zhuzhuang Reservoir Basin

Watershed hydrological model is an effective tool for studying the rule of hydrology change and reasonably allocation water resources. In recent years, the hydrological distribution model becomes more and more important in studying the watershed hydrologic cycle for the development computer, geographic information system and remote sensing technology. The SWAT(Soil and Water Assessment Tool)model which was developed by the United States department of agriculture gricultural research center, due to its benefits of valid physical basis and comprehensively considering the matter of climate, Soil, vegetation, human management etc. makes it increasingly important in the hydrological research.This paper, with the help of GIS technology, established the SWAT model of zhuzhuang reservoir basin and evaluated the applicability of the model. On this basis,we set different land utilization condition to simulate the changing of under laying surface hydrology. The main research conclusions are as follows:⑴Divide the study area. Based on digital elevation model(DEM) extract relevant hydrological information, divided the study area into 19 sub-basin, and then overlaid the land utilization type, soil type and gradient information. Finally, we got241 hydrological response unit(HRU).⑵Construct the SWAT model attribute database. Referring to the Harmonized World Soil Database(HWSD), we got eleven relevant parameters of soil, such as Soil hydrology grouping, maximum root depth of soil profile, and Wet soil density and so on. According to the land using type standard in the database of SWAT reclassified the land use types.⑶Calibrate and validate the model parameters. Through sensitivity analysis we got nine parameters. They are the saturated hydraulic conductivity of soil,compensation coefficient of soil evaporation, base flow coefficient, groundwater delay factor, wet soil density, runoff curve number, soil water can be supply,groundwater evaporation coefficient, the minimum base flow valve value. All the parameters are sensitive to the model. Based on the parameters we can calibrate andvalidate the model.⑷Applicability evaluation. Use the measured hydrologic data from 2005 to 2008 of zhuzhuang reservoir to calibrate the model and use the measured hydrologic data from 2009 to 2010 to verify the model. In calibration period the efficiency coefficient(Ens), the relative error(Re) and correlation coefficient(R2) ratio are 0.71, 17, 0.86.In the verification period the efficiency coefficient(Ens), the relative error(Re) and the correlation coefficient(R2) ratio are 0.77, 11, 0.87. It proves that the model has a good application to zhuchuang reservoir watershed.⑸Aassumed land utilization situation analysis. By the extreme land use method assumed three kinds of land use condition. The results showed that forest and grassland area increase will reduce runoff, and the increase of the arable land will increase runoff; woodland and grassland have a greater water conservation function than the arable land.