A study of the coupling relationship be-tween fractal characteristics of river, geomorphology and tectonic activity in areas around the Tibetan Plateau

The research on the geomorphological characteristics and the mechanism of the formation and evolution in areas around the Tibetan Plateau has been a hot issue in recent years. In this paper, the authors studied the fractal characteristics of the river net-work, geomorphic features and tectonic activity in areas around the Tibetan Plateau. There are strong tectonic activities, frequently strong historical earthquakes, many large earthquakes in the Himalaya fault zone, Longmenshan Mountain fault zone and Altun fault zone, and there are many similarities in river pattern characteristics and geomorphic evolution, such as quick changes of the longitudi-nal profile and concave shape with long wavelength, steep stream gradient ratio, high relief, simple river pattern and low fractal dimen-sion of river. Tectonic activities are not strong on the northeastern margin of the Tibetan Plateau as compared with features of the Hi-malaya fault zone in this aspect, as shown by rare strong historical earthquakes, slow changes of the longitudinal profile and convex shape with long wavelength and micro-amplitude, slow stream gradient ratio, small relief, complex river pattern and high fractal di-mension of river. There are strong tectonic activities, frequent strong historical earthquakes, many large earthquakes on the southeast-ern margin of the Tibetan Plateau, but because the regional average annual erosion rate is very low, and stream trenching is very deep, the change of the longitudinal profile is slow, its shape is convex with long wavelength and micro-amplitude, the stream gradi-ent ratio is slow, the river pattern is complex, and the fractal dimension of the river is high. The authors hold that the regional erosion rate is much more controlled by the tectonic activity than by the precipitation, and therefore the influence of the spatial variation of precipitation can be largely ignored in the analysis of river pattern characteristics.