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汶川大地震对龙门山区造成了严重破坏。地震引发的次生山地灾害以及剧烈的土壤侵蚀仍将长期持续地影响着当地居民的生产与生活。对地震前后小流域的土壤侵蚀严重性进行评价并分析其变化,将对灾后小流域水土保持综合治理及生态恢复与重建工作具有重要的指导意义。基于GIS技术,以四川省彭州市龙门山区为研究区,以小流域作为基本单元,针对研究区地震灾区小流域土壤侵蚀,构建侵蚀严重性指数评价及分级方法,对地震前后土壤侵蚀严重性及变化特征并进行评价与分析。结果表明,地震后绝大部分小流域的土壤侵蚀趋重。震后土壤侵蚀程度不严重、较严重的小流域数量别由震前8个及21个降至5个及8个,新增严重、极严重小流域分别为12个及4个,相应面积分别为183.76 km2,52.70 km2。空间上流域土壤侵蚀严重性由西北向东南递减。地震前后小流域平均海拔、平均坡度与侵蚀严重程度正相关,且平均坡度对侵蚀严重程度加重贡献更大。
The Wenchuan earthquake caused serious damage to the Longmen Mountain. Secondary mountain hazards caused by the earthquake and severe soil erosion will continue to affect the production and livelihood of local residents for the long term. The evaluation of the severity of soil erosion in small watershed before and after the earthquake and the analysis of its changes will have important guiding significance for the comprehensive management of soil and water conservation and ecological restoration and reconstruction in small watershed after the earthquake. Based on the GIS technology and taking Longmen Mountain Area of Pengzhou City in Sichuan Province as the study area and the small watershed as the basic unit, to evaluate the soil erosion severity of the small watershed in the earthquake-stricken area in the study area and to construct the evaluation index and classification method of the erosion severity index, Change characteristics and carry out evaluation and analysis. The results show that the soil erosion aggravates in most small watershed after the earthquake. The degree of soil erosion after the earthquake was not serious. The number of the more serious small watersheds dropped from 8 and 21 before the earthquake to 5 and 8, respectively. The newly serious and extremely serious small watersheds were 12 and 4, respectively, with corresponding areas At 183.76 km2, 52.70 km2. The severity of soil erosion in the basin has decreased from northwest to southeast. Before and after the earthquake, the mean elevation and mean gradient of small watershed were positively correlated with the severity of erosion, and the average gradient contributed more to the severity of erosion.