Distributed Hydrological Simulation Using SWAT In Yellow River Source Region

With the development of computer, geographic information system and remote sensing, distributed hydrological model is being the hydrology and water resource research hot focus because of many aspects of good performance such as land process research, flood and disaster control and water resource forecasting affected by the changing environment. On one hand, distributed hydrological model is relied on calculation and simulation based on physical process, on the other hand, it is focused on how to deal with hydrology information obtained by new methods combining with the model, which together push forward the advance of hydrology simulating technology.Selecting Yellow River Source Region as study area, this thesis simulates the hydrological process and forecasts the water resource response under the changing environment using SWAT on the basis of the analysis of water resource varying trend. The main content includes:(1) Based on former research accomplishment, the thesis synthesizes the theories and methodology of distributed hydrological model, including the methods of how to obtain the watershed parameters and to route the hydrological process based on GIS. It introduces the theory, structure and application of SWAT which consists of climate, hydrology, erosion, plant, pesticide, management, water body, channel. The SWAT command loop is briefly explained and so is its application in basin scale.(2) Using SWAT, the output data model of Yellow River Source Regionhydrological simulation based on Excel VBA is built to simulate 1998-2003 daily hydrograph. The result reflects that correlation coefficient r2 is 0.96, 0.88, 0.80, 0.76, 0.94, 0.94 and Nash coefficient is respectively 0.87, 0.76, 0.53, 0.50, 0.90, 0.84, indicating the good precision.(3) The thesis discusses the runoff effect under the climate and land use changing, and simulates hydrological process based on hypothesis scenarios using calibrated model. The result reflects that runoff drops down 40% when temperature raises up 2°C and precipitation drops down 20%, runoff raises up 55% when temperature drops down 2°C and precipitation raises up 20%. With grassland and woods increasing, runoff decreases. Runoff comes up to 740m3/s increasing 30% when land is baked without any cover.