雅鲁藏布江大拐弯地区河流形态特征及其意义

摘要

为探讨雅鲁藏布江大拐弯地区区域隆升的特点,通过DEM(数字高程模型)和遥感影像提取雅鲁藏布江干流和帕隆藏布江的形态特征,引入Hack剖面、SL参数和Amos河宽理论模型进行分析.雅鲁藏布江干流在大渡卡以下河段的Hack剖面表现为上凸形态,SL参数升高、河流宽度减小,在藏布巴东瀑布-雅鲁藏布江大拐弯顶端段,SL参数达到最大值,河流宽度达到最小值;大拐弯顶端以下河段,SL参数减小,河流渐宽.帕隆藏布江古乡以下河段SL参数梯级增高,河流宽度总体收窄,大拐弯顶端附近达到最大值.综合2条河流的地貌特征和区域地质与地理背景,认为雅鲁藏布江大拐弯地区的隆升具有不均一性,雅鲁藏布江在大渡卡附近开始进入快速隆升区段,隆升最强烈的区段位于藏布巴东瀑布-大拐弯顶端段,大拐弯顶端之后雅鲁藏布江逐渐远离隆升中心区.%In order to probe into the features of uplift in the Great Canyon Region of the Yalung Zangbo River, the authors extracted the morphologies of the Yalung Zangbo River and the Parlung Zangbo River from DEM and remote sensing images, and analyzed them by adopting Hack profile, SL index and the model of Amos river width. The Hack profile of the Yalung Zangbo River which is below Datogka area assumes a convex shape. In this area, the SL index increases and the width of the river decreases. In the Tibet Bubba East Falls, the top of the Great Canyon, the SL index reaches the maximum while the width of the river reaches the minimum. In the river which is below the top of the Great Canyon, the SL index decreases whereas its width becomes wider. In the Parlung Zangbo River which is below Guxiang Village, the SL index increases whereas the width of the river decreases. Combined with the morphology of the two rivers and the regional geological and geographical background, the authors hold that the uplift of the Brahmaputra Great Bend area was heterogeneous, which entered the section with dramatically increasing uplift near Datogka area. The segment which had the strongest uplift is in the possession of Bubba East Falls, the top of the Great Canyon, and after that the Yalung Zangbo River was gradually away from the central area of the uplift.