青藏高原西南部冰川分布与地形因子关系研究

Study on the Relationship between Glacier Distribution and Topographic Factors in the Southwestern Qinghai-Xizang Plateau

摘要: 冰川是冰冻圈的重要组成部分，是中国极其重要的固体水资源，对气候、水资源、环境等有重要影响。以青藏高原西南部冰川为研究区，基于DEM数据提取地形因子，利用均值变点法界定地形因子的最佳分析窗口。将地形因子进行分类，结合冰川分布数据，统计不同等级的地形因子对冰川面积的分布情况，进而研究冰川分布与地形因子之间的关系。结果表明：(1) 基于DEM数据的地形起伏度和地表切割深度的最佳分析窗口为36 × 36个像元的矩形邻域，对应面积约为1.1664 km²，高程变异系数的最佳分析窗口34 × 34个像元的矩形邻域，对应面积约为1.0404 km²。(2) 地形起伏程度由其西北部向东南部、南部递增，冈底斯山出现低起伏地貌特征；地表切割深度和高程变异系数都由其西北部向东南部递增，念青唐古拉山切割深度和高程变异系数显著；喜马拉雅山和念青唐古拉山地表粗糙程度明显；坡度坡向无明显特征。(3) 总体上，青藏高原西南部冰川分布与地形因子有显著的关系：冰川总面积的35%分布在地形起伏度为6.2~6.7的区间；冰川总面积的38%分布在地表切割深度150~270的区间；冰川总面积的28%分布在高程变异系数0.02~0.03的区间；冰川总面积的38%分布在地形粗糙度 < 1.07的区间内；冰川总面积的28%分布在坡度0˚~13˚的区间；冰川总面积的19%分布在北坡上。

Abstract: Glacier is an important part of the cryosphere and an extremely important solid water resource in China, which has an important influence on climate, water resources and environment. Taking the glaciers in the southwest of Qinghai-Xizang Plateau as the study area, terrain factors were extracted based on DEM data, and the optimal analysis window of terrain factors was defined by means of mean change point method. By classifying the topographic factors and combining with the glacier distribution data, the distribution of different levels of topographic factors on the glacier area is counted, and then the relationship between the glacier distribution and topographic factors is studied. Results show that: (1) The optimal analysis window for topographic undulation and surface cutting depth based on DEM data is a rectangular neighborhood of 36 × 36 pixels, corresponding to an area of about 1.1664 km², and the optimal analysis window for the elevation variation coefficient is 34 × 34. The rectangular neighborhood of pixels corresponds to an area of about 1.0404 km². (2) The degree of relief increases from the northwest to the southeast and the south, and the Gangdise mountain is characterized by low relief; The cutting depth and the variation coefficient of elevation increase from the northwest to the southeast, and the cutting depth and the variation coefficient of elevation of Nyainqentanglha mountain are significant; The surface roughness of Himalayas and Nyainqentanglha mountains is obvious; The slope aspect has no obvious characteristics. (3) In general, there is a significant relationship between the distribution of glaciers and topographic factors in the southwest of Qinghai-Xizang Plateau: 35% of the total glacier area is distributed in the range of topographic relief of 6.2~6.7; 38% of the total glacier area is distributed in the range of 150~270 cutting depth; 28% of the total glacier area is distributed in the range of 0.02~0.03; 38% of the total glacier area is distributed in the range of terrain roughness < 1.07; 28% of the total glacier area is distributed on the slope of 0˚~13˚; 19% of the total glacier area is distributed on the north slope.