亚流域划分对分布式水文模型模拟结果的影响

Influence of subdivision of watershed on distributed hydrological model

本文以GIS技术为支持,选择黄河下游支流洛河卢氏水文站以上流域为研究区域,应用分布式水文模型SWAT(SoilandWaterAssessmentTool)在不同的亚流域划分数量条件下进行流域产流和产沙模拟,进而分析亚流域划分对分布式水文模型模拟结果的影响,结果表明:(1)产流量随亚流域数量的增加而增大,变化幅度较小;产沙量随亚流域数量的增加而减小,变化幅度较大;(2)存在一个亚流域划分水平,当超过此水平时亚流域数量的变化对产流量和产沙量几乎没有影响。根据计算流域产沙量的MUSLE方程,分析了由于亚流域划分数量变化对流域产沙的影响,发现在研究区内其主要原因为MUSLE中径流项对亚流域划分数量变化的响应,其次是土壤可蚀性因子、植被覆盖和管理因子和地形因子参数值的统计变化。

The distributed hydrological model-SWAT (Soil and Water Assessment Tool) is applied to analyze the influence of different watershed subdivisions on runoff yield and sediment yield. The result shows that: 1.the runoff yield will increase with the increase of subdivision amount and varies within a small range, but the sediment yield will decrease and varies significantly; 2.a critical subdivision level exists, the subdivision will not affect the runoff and sediment yield if the amount of subdivision exceeds this level. Furthermore, the influence of subdivision level, i.e. the spatial aggregation extent, on sediment yield is investigated by using the MUSLE (Modified Universal Soil Loss Equation). It is found that the term expressing the runoff in the equation is sensitively responding to the subdivision amount in the study area.