基于SWAT模型的清水河流域年径流侵蚀功率空间分布

为了从能量学的角度解释流域水力侵蚀的空间分布情况,选取可以更好表示流域下垫面条件、降雨及其产生的径流对水力侵蚀综合作用的径流侵蚀功率,以宁夏回族自治区水土流失严重的清水河流域为研究对象,基于SWAT模型模拟研究了清水河流域年径流侵蚀功率的空间分布特征及其空间尺度效应。结果表明:(1)清水河流域多年平均径流侵蚀功率在流域内呈现“支流大,干流小; 东部大,西部小”的空间分布规律;(2)当子流域出口断面控制面积小于4 000 km²时,子流域多年平均径流侵蚀功率与子流域出口断面集水面积间呈显著的幂函数关系; 当子流域出口断面集水面积大于4 000 km²时,子流域多年平均径流侵蚀功率稳定在1.56×10^-5 m⁴/(s·km²)左右;(3)优先选择处于清水河上中游区域且出口断面集水面积小于84.85 km²的小流域进行生态治理,可取得良好的水土流失治理效果。因此径流侵蚀功率具有一定空间分布规律且与流域集水面积间具有显著相关关系,掌握这一规律和相关关系可为流域生态治理提供理论支持。

Spatial Distribution of Annual Runoff Erosion Power in Qingshuihe River Basin Based on SWAT Model

In order to explain the spatial distribution of water erosion in Qingshuihe River Basin from the perspective of energetics, this study chose to focus on the runoff erosion power which can better represent the comprehensive effect of underlying surface conditions, also rainfall and its runoff generated on water erosion is selected. The Qingshuihe River Basin suffering from serious soil and water loss located in the Ningxia Hui Autonomous Region was selected as the object of research in this paper. The SWAT model was constructed to study the spatial distribution characteristics and spatial distribution scale effect of annual runoff erosion power in Qingshuihe River Basin. The results show that:(1)The annual average runoff erosion power in the Qingshuihe River Basin presents a spatial distribution law of ‘larger in tributaries than of that in the main stream, and larger in the east region than of that in the west region';(2)When the control area at the outlet section of the sub-basin is less than 4 000 km², there is a significant power function relationship between the mean-annual runoff erosion power of the sub-basin and the control area at the outlet section of the sub-basin. When the control area at the outlet section of the sub-basin is greater than 4 000 km², the mean-annual runoff erosion power of the sub-basin is stable at about 1.56×10^-5 m⁴/(s·km²);(3)The small watershed with the control area at the outlet section has an area of less than 84.85 km², which located in the upper and middle reaches of the Qingshuihe River, has been selected as the comprehensive ecological harness small watershed, which can achieve a good soil erosion control effect. Therefore, the runoff erosion power has a certain spatial distribution law and has a significant correlation with the catchment area of the watershed. Mastering this law and correlation can provide theoretical support for the ecological governance of the watershed.