三峡库区水土流失综合治理优先小流域识别方法

三峡库区水土流失严重,开展水土流失综合治理是减少入库泥沙和提高三峡工程综合效益的关键,而如何高效识别优先小流域,则是提高治理资金效益和科学决策的基础。以重庆市合川区为例,在区域土壤侵蚀评价的基础上,提出了水土流失面积法、土地利用-水土流失面积法和坡度-水土流失面积法3种优先小流域识别方法,并对其进行了比较分析。结果表明,坡度-水土流失面积法识别的优先小流域水土流失面积占比接近于水土流失面积法,同时又将坡度较大以及耕地、园地和采矿用地面积占比较大的小流域识别出来,纳入优先小流域中,是3种方法中最优的识别方法。研究结果可为三峡库区或同类型地区小流域水土流失治理规划与实施顺序决策提供借鉴和参考。

Priority Watershed Determination Methods for Comprehensive Control of Soil and Water Conservation in Three Gorges Reservoir Area

Serious soil erosion exists in the Three Gorges Reservoir area. The comprehensive control of soil and water conservation is the key measure for decreasing the sediment which flow into the Three Gorges Reservoir and improving the comprehensive benefit of the Three Gorges project.Effective identification of the small watershed (priority watershed) with serious soil erosion is the basis for improving the efficiency of fund utilization and scientific decision-making. In this study, Hechuan district in Chongqing was selected as a test area. The regional soil erosion was assessed. The priority watershed was then identified by soil loss area method, landuse-soil loss area method, and slope-soil loss area method. The parameters including the average soil loss area percentage, the percentage of different landuse and average slope degree were used to assess the priority watershed. The results showed that the average soil loss area percentage of priority watershed from slope-soil loss area method was close to those from soil loss area method. However, the priority watersheds with high slope gradient, greater area percentage of crop land, orchard land and mining land were also identified in the slope-soil loss area method. It indicates that the slope-soil loss area method was the best method for identifying priority watershed. The results could serve as the comprehensive soil and water conservation of small watersheds.