Water Cycle Modeling in Hetao Irrigation District of Inner Mongolia based on the Distributed DEHYDROS Model
基于分布式水文学模型的内蒙古河套灌区水循环特征研究

Hetao Irrigation District (HID) is located in Inner Mongolia of China and has an area of approximately 1.1 million ha. It is one of the biggest irrigation diversions in the upper reach of the Yellow River. DEHydroS, a distributed eco-hydrological simulator developed for irrigation districts was applied in this study. This model was developed with the code of CERES-Wheat and Maize, SWAT2000, MODFLOW96, and SWATMOD99. The hydrological components of DEHydroS were used without taking groundwater dynamics component into consideration in this study. Based on the model, the whole irrigation district was divided into 11 sub-basins. Data from 1991 to 2000 were used in calibration and those from 1980 to 1990 were used in validation. Data from 1961 to 2000 were used to investigate the hydrological cycling in the long run. The calibration and validation results showed that DEHYDROS model was applicable in irrigation districts, and the parameters calibrated were acceptable in HID. According to the simulating results for 40 years, the mean evapotranspiration amount was 3.9 billion cubic meters; the mean soil percolation was 1.3 billion cubic meters; the discharge of HID was 7.78 billion cubic meters; and the runoff resulting from precipitation was very little. The annual average water diversion from the Yellow River was 5.14 billion cubic meters, and canal seepage and percolation from soil profile took important part in recharging the shallow groundwater. Groundwater evaporation was very important for supplying water to crop water uptake, and the annual average value amounted to 1.5 billion cubic meters. Baseflow accounted for 43 percent of the total discharge, second to that of evapotranspiration. These results indicated the feasibility of making comprehensive use of surface, soil and ground water information to provide a more physical-based assessment of regional hydrological dynamics.