YAN Xia, ZHOU Yin-jun, YAO Shi-ming
Characterized by various types of valley landscape, the source region of Yangtze River is densely covered by river networks, most of which are still in the process of natural evolution. In this paper, landform in the source region of Yangtze River is investigated based on SRTM3 DEM data of some representative river reaches, inclusive of Chumaer River, Tuotuo River, Dangqu River, Tongtian River, Buqu River, and Gaer River. Water and sediment characteristics are also analyzed from the observed data. According to the river valley shape and river landform, the river channel in the source region can be divided into three types: alluvial plateau, hilly valley, and alpine valley, among which the alluvial plateau is mostly featured by wandering or multiple branches, the hilly valley by single or branching plane form, and the alpine valley by single channel. Among the three source rivers, i.e. the south, north, and due sources, the discharge of Dangqu River (the south source) is the largest, and that of Chumaer River is the smallest; sediment discharge of Tuotuo River is the largest, followed by that of Chumaer River and Dangqu River in sequence. Moreover, suspended sediment in all the wandering river reaches, which is coarser and more uniform, is larger in amount than in straight, curved, or branched river reaches; the width of river channel is positively correlated with the sediment concentration of water flow, which preliminarily explains the causes of alluvial river formation.
