State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China, Xi'an University of Technology, Xi'an 710048, Shaanxi, China.
State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China, Xi'an University of Technology, Xi'an 710048, Shaanxi, China.
Sci Total Environ. 2019 May 10;664:968-974. doi: 10.1016/j.scitotenv.2019.01.378. Epub 2019 Jan 30.
The sediment-reducing effect of check dams and the safety issues following dam breaks are long-standing concerns. This study analyzed the runoff change and sediment source during rainstorms in a small watershed using a multivariate mixed model and a comparative analysis of watersheds. The problem of sediment loss from dammed farmland following check dam break during rainstorms was evaluated. The results showed that the flood peak lag time (PLT) was significantly influenced by pre-soil moisture in cases of small amounts of rainfall but not during rainstorms. Ecological construction significantly reduced the linear correlation between rainfall and runoff modulus (RM). The reduction in sediment delivery modulus (SDM) due to the check dam was more significant than that in RM. The reduction in RM and SDM under rainstorm conditions were 16%-74% and 53%-93%, respectively. The contributions of inter-gully and gully lands to the sediment deposited in dammed farmland during a large rainstorm on July 26, 2017 were 38.07% and 61.93%, respectively. Soil erosion remained significant during large rainstorms. The increase in vegetation coverage on the hill slope increased the amount of sediment from gully lands. Check dam breaches have accounted for a loss of only 1.2% of the total area of the dammed farmland, and thus have not caused a large loss of sediment. However, breaches in them clearly increased the coefficient of variation of RM and SDM. Therefore, check dams have a critical effect on controlling sediment delivery at the watershed scale. Dam breaks do not result in a large percentage of sediment loss in the dammed farmland.
淤地坝的减沙效果和坝体溃决后的安全问题一直是关注的焦点。本研究采用多元混合模型和流域对比分析方法，分析了小流域暴雨条件下的产流产沙变化。评估了暴雨条件下淤地坝坝体失事对坝地土壤侵蚀的影响。结果表明，在小雨量情况下，洪峰滞后时间（PLT）受前期土壤湿度的显著影响，但在暴雨情况下则不受影响。生态建设显著降低了降雨与径流模数（RM）之间的线性相关性。与 RM 相比，淤地坝对输沙模数（SDM）的减少更为显著。在暴雨条件下，RM 和 SDM 的减少幅度分别为 16%74%和 53%93%。在 2017 年 7 月 26 日的大暴雨中，切沟和沟壑对淤地坝中沉积泥沙的贡献率分别为 38.07%和 61.93%。在大暴雨条件下，土壤侵蚀仍很严重。坡面植被覆盖度的增加增加了来自沟壑土地的泥沙量。淤地坝溃决仅占坝地总面积的 1.2%，因此并未造成大量泥沙流失。然而，它们的溃决明显增加了 RM 和 SDM 的变异系数。因此，淤地坝对控制流域尺度的输沙具有重要作用。坝体溃决不会导致坝地土壤侵蚀的大量流失。
