区域尺度侵蚀产沙估算方法研究

Calculation of soil erosion and sediment yield at the regional scale

区域土壤侵蚀模型是大区域土壤侵蚀普查和水土保持宏观决策的支持工具,土壤侵蚀模型的研发是土壤侵蚀学科的前沿领域。基于DEM将区域划分为规则网格,设计产流、产沙过程的单元模型,包括植被截留、入渗、填洼、流速、携沙能力、径流剥蚀量、泥沙沉积等算法。将月降水当作1次降雨事件,并划分若干时段进行迭代计算,利用GIS空间分析功能完成水沙汇集运算,并在ArcGIS支持下进行计算机程序设计,有效地完成了区域侵蚀产沙量的计算。将模型应用于延河流域得到:1995年7月份平均径流深为35.6 mm,径流系数为0.237,流域出口径流量为2.72亿m3,流域出口输沙量为0.38亿t,流域平均侵蚀模数为4575 t/(km2.月);输出图形空间格局和结构符合实际情况,初步模拟结果令人较满意。

Regional soil erosion model is a effective soil and water conservation. The development of soil tool for regional soil erosion survey and policy-making of erosion model is one of the hot issues in soil erosion prediction. Based on DEM the study region was divided into regular cells and models for runoff and sediment processes were designed. The sub-processes of interception, infiltration, surface storage, flow velocity, transport capacity, detachment, and deposition were considered in the regional soil erosion model. The monthly precipi- tation was assumed as one single rainfall event and divided into several periods, which were input for model operation. Accumulation of runoff and sediment among units was calculated by means of spatial analytic function of GIS. The regional runoff and sediment yield were calculated under the help of the computer program which developed on the tools of ArcGIS. The model was applied in Yanhe River watershed and the results showed that the simulated average runoff depth, runoff coefficient, and runoff volume were 35.6 ram, 0. 237, and 272 million m3 respectively. The simulated sediment amount was 38 million tons and the average erosion modulus was 4 574 t/（km^2·month）. The spatial distribution of soil erosion was close to the real situation. In general, the simulated results were satisfied and can be used for regional soil erosion prediction.