Identification and analysis of morphological characteristics of alpine-gorge rivers: A case study of upper reaches of Jinsha River

Abstract

[Objective] To address the problems of complex terrain and difficulty in traditional monitoring in alpine-gorge rivers, river morphological characteristics are clarified using remote sensing technology, providing a theoretical basis for runoff estimation in data-scarce areas. [Methods] Based on multi-source remote sensing data, river morphological characteristics were identified using an improved relative stability index, gradient, and sinuosity. Characteristics of runoff flux-stable river segments were analyzed based on confluence accumulation combined with geological types. The energy conversion frequency of the river was explored based on variations in channel gradients. The hydraulic geometry relationship between discharge and water surface width was verified and analyzed based on the principle of multi-station hydraulic geometry method.[Results]1) The average gradient of the upper reaches of the Jinsha River was 1.71‰, and the stability of river segments was regulated by geological types. The segments from Zhimen Da to Shengba Village(segment I) and from Wentuo Village to Shigu Town(segment III) were identified as stable, while the segment from Shengba Village to Wentuo Village(segment II) was identified as unstable.(2) Energy dissipation in river segments was controlled by geological type and channel gradient. Granite segments were characterized by erosion, while basalt and shale segments showed depositional tendencies.(3) The gradient of runoff flux-stable river segments at hydrological stations was significantly lower than the average gradient of their corresponding geological types, indicating better stability.(4) Hydraulic geometry analysis of the Benzilan river segment showed that the average water surface width at 500 m intervals had a power-law relationship with discharge, and the coefficient and exponent showed a logarithmic linear relationship. The exponent of the width regression equation was approximately equal to the slope of the logarithmic linear equation, which was beneficial for improving the accuracy of discharge estimation. [Conclusion] The stability and morphological characteristics of river segments are controlled by geological types and are closely related to energy dissipation characteristics. The identification of runoff flux-stable river segments can provide scientific support for discharge estimation and hydrological monitoring of alpine-gorge rivers.

Keywords

river morphology / river segment stability / energy dissipation / runoff flux-stable river segment / hydraulic geometry / remote sensing