西柳沟流域拦沙坝沟道冲刷减蚀能力模拟

为探讨风水交错侵蚀区拦沙坝建设对流域沟道侵蚀动力过程及沟道冲刷侵蚀能力的影响,通过分布式水文模型MIKE SHE以及一维水动力模型MIKE 11耦合模拟了西柳沟流域洪水过程,分析了新建拦沙坝建设前后流域沟道侵蚀动力变化,通过建立流域次暴雨水沙响应模型估算了新建拦沙坝工程运行期内的沟道冲刷减蚀能力。结果表明:(1)拦沙坝建成后,流域出口处洪峰流量减少40.90%,洪水总量减小35.85%,显著改变了西柳沟流域洪水过程,洪水过程线明显坦化;(2)流域主沟道平均最大流速、最大径流剪切力和最大径流功率分别减小21.66%,22.02%和34.31%,有效降低了沟道侵蚀动力;(3)在多年平均降水情况下,预计流域新建拦沙坝工程在25年工程运行期内的冲刷减蚀能力可达到3 309.49万t。研究结果可为风水交错侵蚀区拦沙坝减蚀能力评估提供理论支撑。

Simulation on the Gully Erosion Reduction Ability of Check Dam in Xiliugou Basin

In order to scientifically understand the effect of the construction of check dams on the erosion dynamics and the ability to reduce gully erosion in the wind-water cross erosion area, in this study, the Xiliugou Basin, one of the ten tributaries, was taken as the research area, and the differences of flood process, erosion dynamics and energy in gully after the construction of check dams were simulated and quantitatively calculated by coupling the distributed hydrological model MIKE SHE and the one-dimensional hydrodynamic model MIKE 11. The reduction of gully erosion by check dams was also estimated. The results showed that: (1) The check dams decreased the flood peak and flood volume of the outlet section by 40.90% and 35.85%, respectively. (2) The average flow velocity, runoff shear force and runoff power along the main gully of the watershed were dropped by 21.66%, 22.02% and 34.31%, respectively. (3) During the planned operation period of the project, the check dams reduced the amount of gully erosion by 33.094 9 million tons under the condition of multi-year average precipitation. The construction of check dams has significantly changed the flooding process of Xiliugou Basin, which alleviated the erosion dynamics along the main channel as well as provided effective erosion mitigation effects.