Abstract:

In order to study the geomorphologic asymmetric characteristics of the Taohe River drainage basin and discuss the evolution of the Taohe River and the reason of the stream direction sharply changing at Minxian County, a DEM based topographic analysis of mountain belts has been done to extract much drainage and subbasin information and the drainage geomorphic parameters of the Taohe River. Taohe River drainage sub basins and longitudinal channel profiles of the main bedrock channels of different active orogens show that the southern and northern tributaries of the Taohe River are of obviously asymmetry. Almost all the parameters of the upstream northern and downstream eastern basins are smaller than those of the upstream southern and downstream western ones, respectively. And upstream basins are smooth, low relief and mature, which may have formed earlier than the downstream ones. The rapid uplift of the mountain range in the east of Minxian County interrupted the paleo Taohe River, and later on,  the river from the northeast cut through the West Qinling Fault zone by headwater erosion, and then captured the paleo Taohe River near Minxian County and formed the new Taohe River. The structural implications of the geomorphologic asymmetric characteristics of the Taohe River drainage basin for the northeast margin of the Tibetan Plateau within the Late Cenozoic have been discussed.

Key words: Taohe River, digital elevation model (DEM), asymmetry, structural implications