黄土高原重力侵蚀对地貌因素的敏感性分析

地形属性是影响降雨引发重力侵蚀的形成、演变、分布和危害的重要因素。以延安市宝塔区为例,基于已有文献和调查数据,采用GIS和RS技术,以及改进的增长率敏感系数法对影响黄土高原重力侵蚀的地貌等因素进行敏感性分析。结果表明:(1)坡度对重力侵蚀总量、滑坡侵蚀量和崩塌侵蚀量的影响较大,且都呈正相关关系;重力侵蚀总量、滑坡侵蚀量、崩塌侵蚀量对坡度的敏感系数分别达到60.5,1616.6,89.3。(2)对重力侵蚀总量和滑坡侵蚀量而言,距河流距离、高程是次重要影响因素;而对崩塌量而言,植被覆盖率、坡面曲率是次重要影响因素。(3)研究区域中小型重力侵蚀发生次数较多,大型重力侵蚀发生频数较少,但大型重力侵蚀对侵蚀总量的贡献较大;其中,体积大于100×10^4m^3的大型崩滑侵蚀虽然发生频数仅占总数的13%,但其侵蚀量却占重力侵蚀总量的57%。研究结果可为黄土高原地区水土流失综合治理及生态恢复提供参考依据。

Sensitivity Analysis of Gravity Erosion to Topography Factors on the Loess Plateau, China

Topography attributes are the most important factors in controlling the initiation, evolution, distribution and damage of the gravity erosions triggered by rainfall. Based on the existing references and survey data, the revised increase-rate-analysis method, Arc GIS and Remote Sensing were used to evaluate the sensitivity of the gravity erosion to the topography factors in the Baota District, Yan''an City. The results showed that:(1) The slope gradient was the most important influential variable. The total amount of the gravity erosion, the amount of landslide and the amount of avalanche were all positively correlated with the gradients and their sensitivity parameters on the slopes were 60.5, 1 616.6 and 89.3, respectively. (2) For the total amount of gravity erosion and the amount of landslide, the distance to streams and the altitude were the second important factors. For the amount of avalanche, the vegetation cover and slope curvature were the second important factors. (3) The small-scale and medium-scale gravity erosion occurred frequently, and the large-scale gravity erosion had a low occurrence frequency, but the large-scale gravity erosion contributed more to the total amount of the gravity erosion. Among them, the events of large-scale gravity erosions with the amount greater than 100×10⁴ m³ only contributed 13% to the total frequency. Nevertheless, the contribution of the large-scale gravity erosions was up to 57% to the total amount of the failure masses. The results would provide a scientific basis for soil conservation and ecology restoration on the Loess Plateau, China.