Applicability of Geomorphic Index for the Potential Slope Instability in the Three River Region, Eastern Tibetan Plateau.

Feng Liu,Lingjing Li,Xin Yao

doi:10.3390/s21196505

Feng Liu, Lingjing Li + Show 1 more

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https://doi.org/10.3390/s21196505

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Abstract

Geomorphic indices (e.g., the normalized channel steepness index (Ksn) and the stream length-gradient index (SL)) highlight changes in fluvial shapes and gradients. However, the application of these indices was seldom used to identify potential landslide zones. In this study, we used the Ksn and SL indices to detect the significant variations in the stream power along river reaches, which are anomalies associated with landslides, in the Zengqu River watershed, the upper reaches of the Jinsha River. Most of the landslide anomalies originate along the trunk and surrounding tributaries below the knickpoint of the mainstream. This suggests an erosional wave is migrating upstream throughout the drainage area. The fluvial incision may generate over-steepened hillslopes, which could fail in the future. In addition, the divide asymmetry index (DAI) predicts the direction of the divide as the headwaters migrate toward lower relief, higher elevation surfaces. Landslides are expected to occur as the unstable divide migrates. The proposed methodology can benefit the detection and characterization of potential landslide zones. It should improve hazard and risk analysis and the identification of drainage network areas associated with landslides.

Highlights

Landslides are highly stochastic geomorphological processes that shape the Earth’s landscapes [1,2], causing economic and life losses due to widespread spatial distribution [3].The landslide hazard mitigation cannot do without the identification of the conditioning factors [4]
We identified 30 stream length-gradient (SL)-HCA anomalies in the study area
The SL index was used to investigate the abnormal gradient along the Zengqu River

Summary

Introduction

Landslides are highly stochastic geomorphological processes that shape the Earth’s landscapes [1,2], causing economic and life losses due to widespread spatial distribution [3].The landslide hazard mitigation cannot do without the identification of the conditioning factors [4]. The use of optical remote sensing imaging for landslide detection is mainly based on various markers associated with the surface morphological features of the affected area [5,6,7]. It only provides synoptic information about the post-failure deformation surface features and lacks information about the previous deformation state [8]. The anomalous values of the stream length-gradient (SL) index were used to analyze the change in the gradient along a channel affected by landslides [12,13,14,15]. This study aimed to provide a means of diagnosing potential hillslope failure on the valley side and drainage

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