抚仙湖流域地貌特征及其构造指示意义

GEOMORPHOLOGY OF THE FUXIANHU DRAINAGE BASIN AND ITS STRUCTURAL IMPLICATION

以数字高程模型数据为基础,运用ArcGIS软件平台,从数字高程模型数据中提取抚仙湖流域内相对独立的61个亚流域,其中34个位于小江断裂东侧的山地中,另外27个位于小江断裂西侧的山地中;然后计算每一个流域单元流域的面积、周长、河流总长、形状指数、平均坡度、相对高差以及高程-面积积分值和水系分支比,划分流域等级等。通过对流域地貌参数以及高程-面积积分值和分支比等的特征参数的详细分析,初步表明抚仙湖两侧水系和亚流域的发育具有东西分异的特征。这些特征指示了抚仙湖水系两侧晚新生代构造活动的差异性,反映了小江断裂带东西两侧的不均衡抬升。小江断裂带的活动控制了抚仙湖流域晚新生代快速隆起,滇中高原快速隆起以及小江构造带内部差异活动是造成抚仙湖流域东西差异特征地貌的主要原因。

We took adavage of ArcGIS software platform to obtain the data of geometrical shapes and boundaries of 61 sublevel individual watersheds in the Fuxianhu drainage With SRTM-DEM as the basic data,34 in the ridges east to Xiaojiang fault,27 in the ridges west to the Xiaojiang fault.Afterwards,we calculated the watershed areas,perimeters,river lengths,shape indexs,average slopes,relative height differences,elevation-area integral values,the drainage branching ratios and the level of the 61 watersheds.The results show some differences between the east and west ridges.These features indicates the difference in Late Cenozoic tectonic activity on both sides of the Fuxianhu drainage and reflects the uneven uplift on east and west sides of the Xiaojiang fault zone.The activity of the Xiaojiang fault zone imposed a control over the rapid uplift of the Fuxianhu drainage during the Late Cenozoic basin,and the rapid uplift of the Central Yunnan Plateau and the difference in activity of interior of the Xiaojiang fault zone are the leading factors causing the different topographies on east and west sides of the Fuxian drainage.