考虑沟-坡分异的黄土高原大中流域侵蚀产沙模型

Erosion and Sediment Yield Model of Big and Middle Scale Watershed in Loess Plateau Considering Differentiation Between Upper and Lower of the Shoulder Line of Valleys

针对黄土高原坡面沟缘线上、下侵蚀产沙分异显著的特点,以及机理模型在大中流域不易应用的现状,利用基于Hc-DEM的沟缘线自动提取技术,划分流域沟间地和沟谷地地貌单元.在改进坡长因子算法和改造沟坡侵蚀模型的基础上,提出沟间地运用通用土壤流失方程为模型框架评估面蚀为主的坡地侵蚀,沟谷地运用改造沟坡侵蚀模型评估冲蚀为主的沟谷侵蚀,并与泥沙输移比分布模型集成确定流域侵蚀产沙分布的模型体系.经在北洛河上游流域检验,模型体系能良好模拟流域多年平均侵蚀产沙,在年际尺度也具有较好可靠性,可为黄土高原大中流域水土保持效益评价和水土流失防治规划提供技术支撑.

Erosion and sediment yield between the upper and lower of valleys shoulder line in Loess Plateau are very different.Uncertainty exists while applying mechanism model in big and middle scale watershed.Under this circumstance,automatic extraction technology of the shoulder line of valleys with hydrologically correct digital elevation model data was introduced to divide topography units into inter-gully and gully bank.Through improving the algorithm of slope length factor and re-construction of valley slope erosion model structure, it was put forward that erosion in inter-gully unit and gully bank unit could be calculated respectively by universal soil loss equation and reformed slope-gully erosion statistic model, which were further integrated with sediment delivery distributed model to construct the model system for simulating the distribution of erosion and sediment yield of watershed.The simulation result in the upper reaches of Beiluo River shows that the model system can well simulate erosion and sediment yield of watershed in the scales of annual average and inter-annual.This provided a credible proof on that the model system was useful in benefits evaluating, prevention and control planning of water and soil conservation for large and middle watersheds of Loess Plateau.