Features and Simulation of Surface Water Balance in Semi-arid Areas
半干旱地区地表水平衡的特征和模拟

In this paper, the features of surface water balance in semi-arid regions of northern China were analyzed. These regions are located along the northern margin of East Asian monsoon region, where precipitation concentrates in summer and is mostly produced by convection system. Dry climate causes high potential evapotranspiration, most precipitation is exhausted by evaporation, and surface runoff accounts for only a small part. In winter, snow accumulates and melts fast in spring. Snowmelt flood and a summer flood display a double peak pattern of discharge route. In order to simulate the precipitation-runoff features in semi-arid regions, an Atmosphere-Vegetation Interaction model (AVIM) with detailed energy and water transfer processes between atmosphere, vegetation and soil was used. In this version of AVIM, runoff production caused by both excess infiltration and over saturation were taken into consideration and a snowcover model is involved. New schemes were validated for Xilin River basin and surface water budgets, and runoff generation and snowmelting processes were simulated well. The simulation results show the efficiency of new schemes.