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建立流域土壤水蚀预报模型将为小流域综合治理、土地利用规划等宏观决策提供依据,为小流域水土保持效果有效评价提供参考。通过对小流域侵蚀动态过程的分析,在水流连续方程、动量守恒方程及泥沙质量守恒方程基础上,对坡面-沟道及各沟道间土壤侵蚀时空关系进行合理耦合,建立了流域系统土壤侵蚀动态模拟过程模型;采用有限元方法对土壤侵蚀模拟模型进行数值离散,建立了小流域系统数值离散模型;在确定流域时空离散方法基础上,采用VC++语言编制流域水蚀模拟程序;在室内人工模拟降雨条件下,对模型小流域50mm/h降雨强度,5min降雨历时情况下土壤侵蚀情况进行模拟,在得到流域内典型点处径流流量、径流含沙量及各沟道流速动态过程的同时,将流域内各沟道出口处模拟结果与测量结果比较,径流流量、径流含沙量、流速模拟精度均高于80%。研究结果表明小流域土壤侵蚀模拟模型的建立是可靠的,模型的数值离散方法及编制的计算程序是完全可行的。这一模型的建立将为小流域土壤侵蚀动态过程的模拟预报及实现由小流域向中大流域的侵蚀动态模拟预报提供一定的理论基础。
The establishment of soil erosion prediction model for watershed will provide the basis for macroscopic decision-making in comprehensive management of small watershed and land use planning, which can provide reference for effective evaluation of soil and water conservation in small watershed. Based on the analysis of the dynamic process of erosion in small watershed, based on the equations of water flow continuity, momentum conservation and sediment mass conservation, the spatio-temporal relationships of soil erosion between slope-channel and each channel are reasonably coupled, and the basin system Soil erosion dynamic simulation process model; Finite element method was used to numerical simulation of soil erosion, the numerical model of small watershed was built; Based on the method of spatial and temporal dispersion of watershed, VC ++ language was used to prepare the water erosion simulation program; Under simulated rainfall conditions, the soil erosion under the condition of 50 mm / h rainfall intensity and 5 min rainfall duration was modeled in the model watershed. While the dynamic process of runoff, runoff and sediment concentration and velocity of each channel were obtained, The simulation results at the outlet of each channel in the basin were compared with the measured results. The runoff, runoff and sediment concentration, and flow velocity simulation accuracy were all above 80%. The results show that the establishment of the soil erosion simulation model in small watershed is reliable. The numerical discrete method and the calculation program are completely feasible. The establishment of this model will provide a theoretical basis for the simulation and prediction of the dynamic process of soil erosion in small watershed and the realization of the dynamic simulation of the erosion from the small watershed to the middle and large watershed.