青藏高原坡度坡长因子(LS)空间格局及影响因素分析

地形是影响土壤侵蚀的主要因素，但目前关于青藏高原地形因子的分布格局和影响因素有待研究。基于1弧秒分辨率的SRTM(shuttle radar topography mission)高程数据，计算坡度、坡长、LS因子(slope length and steepness factors,LS),结合高程积分和Hack剖面等，对青藏高原LS因子的分布格局、统计分布特征和影响因素进行研究，结果表明：(1)坡度、坡长和LS因子这3个地形指标，均表现出高原内部小、四周高山大的格局，内流区与外流区的坡度均值分别为6.55°和14.3°,坡长均值分别为122.9,172.2 m,LS均值分别为4.8和12.7;(2)青藏高原LS因子整体受坡度影响，但高原边缘陡峭地区LS因子主要受坡长影响；(3)青藏高原6条主要河流的Hack剖面都呈上凸形态，该地区地貌演化整体上处于幼年期；(4)青藏高原LS因子的分布特征与土壤侵蚀类型及其组合有对应关系：周边地区的高值对应冰川侵蚀—水蚀，西北部的低值对应水力—冻融侵蚀和风蚀，东南部边缘向高原内部过渡地区的较高值对应水力—重力侵蚀。通过分析LS因子的分布格局和统计特征...

Spatial Pattern and Influencing Factors of Slope Length and Steepness Factors (LS) in Qinghai-Tibet Plateau

Topography is the main factor influencing soil erosion, but the distribution pattern and influencing factors of topographic factors on the Qinghai-Tibet Plateau (QTP) need to be studied. Based on the 1 arc resolution SRTM (Shuttle Radar Topography Mission) elevation data, we calculated the slope, slope length and LS factor (slope length and steepness factors, LS), and studied the distribution pattern, statistical distribution characteristics and influencing factors of LS factors on the QTP in combination with area-elevation integration and Hack profile. The results show that: (1) The three topographic indexes of slope, slope length and LS factors all showed the pattern of that small in the center of the plateau and large in the around high mountains, and the average slope gradient of the inner flow area and the outer flow area was 6.55° and 14.3°, the average of slope length was 122.9 and 172.2 m, the mean LS factor was 4.8 and 12.7, respectively. (2) On the whole, the LS factor on the QTP was mainly affected by slope steepness, but the LS factor in the steep areas on the edge of the plateau was mainly affected by slope length. (3) The Hack profiles of the six main rivers in the QTP were convex, and the geomorphic evolution of the region was in its youth stage as a whole. (4) The distribution characteristics of LS factor on the QTP were consistent with soil erosion types and their combinations. The high value in the surrounding area corresponded to Glacier erosion-water erosion, the low value in the northwest corresponded to hydraulic freeze-thaw erosion and wind erosion, and the high value in the transition area from the southeast edge to the interior of the plateau corresponded to hydraulic gravity erosion. The distribution pattern and statistical characteristics of LS factor analyzed in this paper could provide theoretical and data support for the evaluation of soil erosion, and also had great significance for the study of material migration and transformation in the earth system of the QTP.