基于面积-高程积分的叶尔羌河山区流域地貌发育特征及其控制因素研究

以叶尔羌河山区流域为研究对象, 利用ArcGIS中的水文分析工具获得1357个集水区的面积-高程积分(HI)值, 定量化研究帕米尔弧形构造带东缘叶尔羌河山区流域的地貌发育特征及其控制因素。结果表明: 1)叶尔羌河山区流域的1357个集水区面积与HI均值的相关性较差(R²=0.0936), 表明集水区面积对HI均值的影响较小; 2)HI值介于0.0717~0.6485, 均值为0.4056, 整体处于地貌发展的壮年期, 是构造、岩性和气候等因素共同作用的结果; 3)HI均值排序为断裂带区域(0.4148)>整个流域(0.4056)>非断裂带区域(0.4004), 表明构造活动是地貌发育的影响因素, 其影响主要表现在断裂带的规模和活动性; 4)非断裂带区域不同岩性的HI均值排序为: 变质岩(0.491353)>冰、雪及现代冰川(0.491351)>花岗岩(0.4426)>海相沉积岩(0.4098)>陆相沉积岩(0.3890)>海陆交互相沉积岩(0.3813)>第四系沉积物(0.3598), 表明岩性是地貌发育的重要影响因素, 且岩石的抗侵蚀能力差异是影响岩性与地貌的关系的重要因素; 5)气候主要通过降水和气温控制河流径流量来影响河流的侵蚀作用和搬运作用进而影响流域内地貌发育, 多年平均年降水对流域的地貌发育的影响较小, 多年平均年气温对流域的地貌发育有特别重要的影响, 是气候对地貌发育的主要控制因素。

Study on geomorphic development characteristics and control factors of mountainous watershed of the Yarkant River based onHypsometric Integral

Pamir syntax is an active structural belt, existing abundant problems of geomorphic evolution, and lacking discussion on the relationship between tectonic, climate, other factors and geomorphic development. However, Yarkant River Basin(34°50 '~40°31'N, 74°28 '~80°54'E) is located in the east edge of Pamir syntax, which is divided into southern mountain basin and northern plain basin. As a whole, the development of fault zones in the Yarkant River Basin is controlled by Karakoram Fault, Karakax Fault and Kashgar-Yecheng transfer system from west to east, and magmatic rocks, metamorphic rocks and sedimentary rocks are widely exposed in the mountain basin. Therefore, mountainous watershed of the Yarkant River(MYR)is an ideal place to study the geomorphic characteristics of Pamir syntax. The DEM data of MYR(with a spatial resolution of 30m×30m, the spatial reference is WGS＿1984＿UTM＿ZONE＿43N, download from http://www.gscloud.cn)were processed by using the Hydrological Analysis Tools of ArcGIS 10.2. We extracted Hypsometric Integral(HI) values in order to quantitatively study the geomorphic development characteristics of MYR, and discussed the relationship between structure, lithology, climate and geomorphic development. We obtained 1357 watersheds, and the correlation with the mean HI value is poor(R2=0.0936)indicating that the watershed has little impact on the mean HI value in MYR. We found the HI values of watersheds in MYR range from 0.0717 to 0.6485, with an average value of 0.4056, identified geomorphological development trend in mature stage, which attributed to tectonic, lithology and climate. And order of mean HI value of MYR is strong tectonic activity areas(0.4148)>the whole basin(0.4056)>weak tectonic activity areas(0.4004), which suggested tectonic is a factor affecting the geomorphic development of the basin, and its effect on the geomorphic development is mainly reflected in the size and activity of the fault zones. And then, the sequence of mean HI value of different lithology in weak tectonic activity areas in MYR is metamorphic rocks(0.491353)>ice, snow and modern glaciers(0.491351)>granite(0.4426)>marine sedimentary rocks(0.4098)>continental sedimentary rocks(0.3890)>marine interbed continental sedimentary rocks(0.3813)>Quaternary sediments(0.3598), which indicated the difference of rock erosion resistance is an important factor affecting the relationship between lithology and topography. In addition, the climate in MYR mainly controlled the regional runoff amount through precipitation and temperature to affect the erosion in catchment and transportation of rivers, and affects the geomorphic development. However, the average annual precipitation has less influence on the geomorphic development of the basin than the mean annual temperature in MYR. Our study provides evidence of intense and continuous of the mean annual temperature is the main factor of climate affecting the geomorphic development in MYR.