基于SWAT模型的最佳管理措施对伊逊河流域水沙的影响研究

Impact of best management practices on water and sediment in Yixun River basin based on SWAT model

为研究防治伊逊河流域水土流失的有效管理措施,笔者在伊逊河流域建立SWAT模型,在流域尺度上模拟退耕还林、植被过滤带和植草水道3种最佳管理措施共7种情景,并且定量分析了水沙的削减效果。结果表明:韩家营水文站径流和泥沙模拟的NSE、R^(2)和PBIAS 3个评价指标均满足SWAT模型的适用性要求;不同管理措施对径流削减率为0.83%~4.05%,其中植草水道对径流的削减率最大,其他管理措施对径流的削减率差异不大;不同管理措施对泥沙的削减效果差异明显,削减率由高到低依次为:5 m的植被过滤带>3 m的植被过滤带>退耕还林(全部耕地)>1 m的植被过滤带>退耕还林(15°以上)>植草水道>退耕还林(25°以上)。植被过滤带对泥沙的削减效果最好,削减效率可达36.18%~56.12%;退耕还林可以削减14.42%~38.05%的泥沙;植草水道也可以削减23.05%的泥沙。因此最佳管理措施可以有效地防治伊逊河流域水土流失,仅从对径流和泥沙的影响方面考虑,推荐选择5 m的植被过滤带。

In order to study the effective management practices to prevent and control water and soil loss in the Yixun River basin,the authors established SWAT model in the Yixun River basin,simulated seven scenarios of three best management practices,namely,returning farmland to forests,vegetation filter strip and grassed waterway on watershed scale,and quantitatively analyzed the reduction effect of water and sediment.The results showed that NSE,R^(2)and PBIAS of runoff and sediment simulation at the Hanjiaying hydrological station all met the applicability requirements of SWAT model.The reduction efficiency of runoff by different management practices was 0.83%~4.05%,among which the reduction efficiency of runoff by grassed waterway was the largest,while the reduction efficiency of runoff by other management practices had little difference.The effects of different management practices on sediment reduction were obviously different,and the reduction rate from high to low was as follows:vegetation filter strip with width of 5 m>vegetation filter strip with width of 3 m>returning farmland to forest(all cultivated land)>vegetation filter strip with width of 1 m>returning farmland with slopes above 15°to forest>grassed waterway>returning farmland with slopes above 25°to forest.Vegetation filter strip had the best effect on sediment reduction,and the reduction efficiency was up to 36.18%~56.12%.Returning farmland to forests can reduce the sediment by 14.42%~38.05%.Grassed waterways can also reduce sediment by 23.05%.Therefore,the best management practices can effectively prevent and control water and soil loss in the Yixun River basin,and it is best to choose vegetation filter strip with width of 5 m,considering only the impact on runoff and sediment.