2000-2012年三峡库区土壤侵蚀动态变化——以重庆市万州区为例

目的]研究重庆市万州区土壤侵蚀在三峡成库前后的动态变化特征，为区域防治水土流失和改善土地利用提供科学依据。方法]运用修正通用土壤流失方程（RUSLE）和GIS工具，基于各期基础数据，分析万州区2000-2012年土壤侵蚀的动态变化过程。结果]（1）2000-2012年万州区年均土壤侵蚀模数经历了先下降后小幅回升的变化过程，最小值出现在2007年，2012年较之2000年剧烈侵蚀区面积下降了34.24%，微度侵蚀区面积上升了7.66%；（2）研究期内，万州区侵蚀等级转化的空间分布与侵蚀分布具有较高的相似性，侵蚀等级转化活跃斑块集中于铁峰山与方斗山之间的丘陵低山地区，东南侧山地区域转化活跃度较低；（3）土壤侵蚀强度等级转移矩阵表明2000-2012年侵蚀强度整体向低等转化；其中2000-2007年土壤侵蚀强度不变地区占76.56%，22.78%的区域向低级转化，转变幅度较大；2007-2012年侵蚀呈现相反的转变态势，稳定比例较高，仅有9.77%的区域向高级转化。结论]2000-2012年万州地区地表的侵蚀状况在逐步减轻，土壤侵蚀强度下降明显，但2007年之后侵蚀状况有所反弹，部分区域的侵蚀形势仍较为严峻，应进一步制定有效的侵蚀防治方案，推进合理的土地利用措施，降低侵蚀量，提高土壤保持能力。

Dynamic Changes of Soil Erosion in Three Gorges Reservoir Area from 2000 to 2012 -A Case Study at Wanzhou District of Chongqing City

Objective] The study analyzed soil erosion in different stages during the construction of Three Gorges Project in order to give support to decrease soil erosion and to improve land-use plan.Methods] Wanzhou District of Chongqing City was taken as research region, the original observed data, revised universal soil loss equation(RUSLE) and GIS method were applied to investigate the dynamic changes of soil erosion.Results] The result showed that from year 2000 to 2012, soil erosion intensity decline first and reached the lowest in 2007, then rose slightly. Severe erosive area decreased by 34.24%, and mild erosive area increased by 7.66%. The spatial distribution of soil erosion grade variation was similar to that of actual soil erosion during the study period. Soil erosion grade variation also had the same distribution characteristics in different period. The most active change of erosive grade concentrated in the area between Tiefeng mountain and Fangdou mountain. The southeast part of the research area had low activity in grade change. Transfer matrix of soil erosion intensity showed that soil erosion intensity declined from 2000 to 2012. From 2000 to 2007, about 76.56% of the research area stayed at its original level; 22.78% of the area downgraded gradually. The second stage, from 2007 to 2012, trend of change in erosion intensity was stable, merely 9.77% of the area transformed to higher level.Conclusion] In 2000-2012, the soil erosion of the surface at Wanzhou District was gradually, and the soil erosion decreased obviously, but after 2007, the erosion situation rebounded, and the erosion situation in some areas was still serious. There is still a strong need for adopting soil erosion control measures, for improving land use measures, and reducing erosion and raising the level of soil conservation.