Discussion on Soil and Water Conservation Activities Hydrological Effects Simulation in the Loess Plateau

The Loess Plateau is the main water collection and the sediment production area of the Yellow River. The water resource crisis and the heavy flood inducing soil erosion coexist in this area. As a result the eco-environment is deteriorating rapidly. The Soil and Water Conservation Activities (SWCA) have taking place almost on every hill slope in the Loess Plateau almost three decades. SWCA, however, can change hydrological cycle strongly by intensifying the infiltration and weakening the overland runoff. Therefore, the research on the hydrological effects of SWCA is important to forecast the long-term hydrological and sediment situation changes trend of the Yellow River. The paper presents the progresses and the problems about recent research on this issue. Due to the structure of distributed hydrological models and the Loess Plateau hydrological effects characteristics, the distributed hydrological models promised a good way to simulate the hydrological effects of SWCA. Moreover, this paper indicates that the distributed hydrological models determine the flow direction(s) and the overland runoff quantity distribution on the hill slope by single factor, gradient. In order to accurately simulate the hydrological effects of SWCA, the distributed hydrological models should consider the impact of flow resistance factors to be more physically based.