淤地坝对流域水沙影响模拟研究

使用SWAT模型，结合淤地坝特点对模型自带的水库模型进行修正来设置淤地坝模块，研究淤地坝对流域径流和输沙的影响，并在内蒙古十大孔兑之一的西柳沟流域进行模拟和验证。以1980-1990年为率定期、2006-2015年为验证期，龙头拐水文站模拟径流量和输沙量与实测值拟合较好，线性拟合系数R²和纳什效率系数E_NS均超过0.6，说明SWAT模型中的水库模型可用于淤地坝模拟。结果表明：其他参数不变的情况下，淤地坝对流域的径流量有一定影响，能够拦截一部分径流量，对流域输沙量的影响巨大，减沙效果明显；淤地坝在一定程度上能影响流域的汇流过程，使得汛期后的月份中出现模拟径流量大于实测径流量的现象；相较于经验公式法，SWAT模型能够提高淤地坝对流域水沙影响的模拟精度；为更好地利用SWAT模型模拟淤地坝对流域径流和输沙的影响，淤地坝模块仍有待改进。

Simulation on impacts of check dams on runoff and sediment load in a watershed

In SWAT model, the built in reservoir model was modified based on the characteristics of check dams to set up the check dam module, with which the impacts of check dams on runoff and sediment load in a watershed was studied, and then the model was verified in the simulation of Xiliugou Basin which is one of the ten tributaries in Inner Mongolia. Taking 1980-1990 as the calibration period and 2006-2015 as the verification period, the simulated runoff and sediment load of Longtouguai station fit well with the observed value, and the linear fitting coefficient (R²) and the Nash-Sutcliffe efficiency coefficient (E_NS) were both greater than 0.6, which indicates that the built in reservoir mode can be used for the simulation of check dams. The simulation results show that when the other parameters remain unchanged, the check dam has a certain impact on the runoff and can intercept part of it, moreover the check dam can greatly reduce the sediment load. Check dams can affect the confluence process of a basin to some extent, making the simulated runoff larger than the observed value in the months after the flood season. Compared with the empirical formula method, SWAT model can improve the accuracy of the simulation on impacts of check dams on runoff and sediment load in a watershed. In order to make better use of SWAT model for these simulations, the check dam module needs to be further improved.