MIKE耦合模型模拟淤地坝对小流域暴雨洪水过程的影响

为科学认识淤地坝建设对黄土高原小流域暴雨洪水过程的影响,该文通过分布式水文模型MIKE SHE和一维水动力模型MIKE 11耦合模拟了不同坝型组合和坝系级联方式下的小流域暴雨洪水过程,研究表明:1)淤地坝系建成后会使小流域洪水的洪峰和洪水总量明显减少,其中骨干坝减幅最小,中型坝次之,小型坝减幅最大;串联、并联、混联3种坝系级联方式均使洪峰流量和洪水总量明显减小,其中混联坝系减幅最大,并联坝系次之,串联坝系最小。2)淤地坝建设改变了洪水历时,其中骨干坝和中型坝增加了洪水历时,而小型坝缩短洪水历时。3)沟道连通性指数与洪峰流量、洪水总量均有很好的相关关系,淤地坝建设明显降低了沟道连通性,通过改变沟道连通性调控了小流域的暴雨洪水过程。可为黄土高原淤地坝安全运行提供科学依据。

MIKE coupling model simulating effect of check dam construction on storm flood process in small watershed

Check dam is a kind of channel management engineering measure for channel erosion control, sediment retention, reduction of flood and sediment disasters. According to the "Check Dam Planning of Soil and Water Conservation on the Loess Plateau" of the Ministry of Water Resources, 160 thousand check dams will be built on the Loess Plateau region by 2020. The construction of such a large number of check dams leads to so extremely severe a flood control situation of check dam that if there is any carelessness, the safe operation and benefit of check dam will be affected. Based on the coupling of distributed hydrological model MIKE SHE and one dimensional hydrodynamic model MIKE 11, a torrential rain flood model in Wangmaogou watershed was established in this paper and the runoff process measured at the outlet of the basin was selected as the calibration parameter. At the same time, 2 typical rainstorm and flood processes in the observed years were used to calibrate the model, and the other 2 single storms were used to verify. The results showed that the model had high precision and could be used to analyze the working conditions. By simulating the rainstorm flood process of small watershed under different combinations of dam types and different dam system cascade modes, the results were obtained as follows: 1) The torrential rain flood model of Wangmaogou watershed based on the coupling of MIKE SHE and MIKE 11 had a Nash-Sutcliffe efficiency coefficient of higher than 0.8 and a determination coefficient (R2) of higher than 0.85 during the calibration period, while higher than 0.6 and 0.7 respectively during the verification period, which indicated that the model could be used to simulate the single rainstorm flood process in small watershed on the Loess Plateau. 2) The construction of check dam system would obviously cut the flood peak and flood volume of the watershed, among which the amplitude reduction of the key dam was the least, the medium dam was the second and the small dam was the largest. The flood peak and flood volume were significantly reduced under 3 cascading modes, i.e. series, parallel and hybrid connection of check dam system, in which the hybrid connection of dam system had the largest decrease amplitude, the parallel dam system took the second place and the series dam system was the last. 3) The dam construction changed the flood duration. The key dam and the medium dam made it increased while the small dam decreased. 4) Check dam construction obviously reduced the channel connectivity. There was a good correlation between the channel connectivity index and the flood peak as well as the flood volume with the correlation coefficient of 0.97 and 0.89 respectively, which meant that check dam system regulated the rainstorm and flood process of small watershed by changing the channel connectivity. The research results are expected to optimize the dam system layout of the check dam in small watershed and provide scientific basis for the construction and safe operation of check dam on the Loess Plateau.