Study On Improvement Of SWAT Model And Integrated Simulation In The Upper-middle Heihe River Basin

Heihe river is the second largest inland river in China, the Zhangye in the middle of Heihe river basin(HRB) is an important commodity grain production base of the northwest of China. The water resources consumption per capita is57%of the national average levels in the middle basin. The water problem has seriously hampered the region’s economic and social development, it also affect the ecological protection and restoration of the lower of HRB. Therefore, the quantitative study of the runoff process in the upper-middle of HRB is of great significance for the rational allocation and utilization of regional water resources.For the hydrological characteristics and agricultural production characteristics of the upper-middle HRB to simulate, this paper choose the watershed scale and farm scale integrated SWAT-APEX model system to quantitative simulation the runoff of the upper-middle HRB in the different spatial discretization ways. The main contents and results of the study are summarized as follows:1. Established the database of the upper-middle HRB combining remote sensing, GIS, measurements with mathematical statistics, the runoff process was simulated in upper-middle HRB from2001to2009, by the methods of remote sensing, GIS, field survey and mathematical statistics. And then, the paper analyzes the problems of HRB SWAT model by the means of importation of upstream water content and single simulation of SWAT model. The groundwater is the main water resource of the middle of HRB in winter, and the groundwater is reused many times because of the complex geographical environment and agricultural water features, which influences the simulation result seriously. To addressed the problem, this paper used the empirical formula to modify the model, which increased the underground runoff by adjusting the infiltration of soil water to improve the simulation result in winter. Efficiency ENS increased to0.70and the correlation coefficient R2also increased to0.71in validation of the model and the results showed that this method enhanced the application of SWAT model in middle of HRB.2. The farm-scale APEX model is used to simulate land surface hydrologic processes in the agricultural irrigation area of the middle HRB. The result is imported to the SWAT-APEX model to calculate the channel processes. The integrated simulation of hydrological processes of upper and middle of HRB improves the simulation precision and spatial resolution of quantitative analysis in the middle of HRB.