疏勒河上游流域地面坡谱特征

Slope spectrum characteristics of the Shule River's upstream basin

坡谱是以某项坡面因子为自变量,其对应的地面面积为因变量所构成的统计图表或模型。坡谱用微观的地形因子反映宏观的地貌特征的空间分异。以ASTER GDEM V002作为基础数据,利用Arc GIS中数字地形分析工具,提取了疏勒河上游流域的地面坡度、坡向、坡度变率、坡向变率,并分别进行了面积统计,绘制了坡谱曲线。结果显示:研究区以陡坡、斜坡为主,二者占总面积的74.16%,陡坡主要分布在疏勒南山、托来南山,斜坡则主要分布在山脉与盆地的过渡地带。在疏勒河盆地和昌马盆地,坡度变率较小,而坡向变率则较大。疏勒河上游流域地面坡谱反映出研究区地面起伏大,地形破碎。坡度变率、坡向变率对山脊线、疏勒河沟沿线具有重要的指示作用。

The slope spectrum is defined by a statistic graph or a mathematical model, in which, the X-axis （in- dependent variable） denotes the numerical values of a particular slope factor and the Y-axis （dependent variable） represents the corresponding area on the ground. It reflects macro spatial distribution rules of different landforms by micro topographical factors. In this study, the ASTER GDEM V002 was utilized as basic data, and the digital terrain analysis tools were applied in ArcGIS to extract the slope, aspect, slope variability （SOS）, and aspect vari- ability （SOA） from the upstream basin of the Shule River, then the statistics results of the areas were conducted to render the slope spectrum curves. The results indicate that the values of the slope from the study area is mainly distributed in a range of 0 ~ 73.20 degrees, and the average is about 18.39 degree. Based on the distribution areas and their percentage portions of the whole area, steep slope （5° - 35° ） and abrupt slope （5° - 15° ） are the major slope types, which occupies 39.89% and 34.27% separately. The steep slopes are mostly distributed in Shulenan Mountain area and Tuolainan Mountain area, while the abrupt slopes are mostly located in transition zones be- tween mountain and basin. And furthermore, the northern part is gentle, while the southern part is relatively steep. 28.33% of aspects are northward and northwestward, which is consistent with the trend of the mountains and riv- ers in the study area. On the left side of Shule River, aspects are generally eastward, and westward on the right side. The SOS values distribute within the range of 0 -47.04°and 53.04% of them are centered between 5 °to 15°. The SOA values change from 0~to 82.13°and 58.08% are focused between 35°and 90°. Particularly, the SOS varies slowly but the SOA changes greatly in both of the Shule river basin and the Changrna basin. The slope spectrum from the upstream of the Shule River reflects that the surface relief moves largely and the terrain goes into pieces on the ground. Combining with the analysis of DEM data, it is obviously that SOS and SOA have sig- nificant indication to the boundary line and shoulder-line of the upstream basin of the Shule River. The slope spec- trum characteristics of the upstream basin of Shule River can be used to effectively distinguish the types and geo- morphologic characteristics of the study area.