Climate change impacts on hydrological landslide triggering in the northern Himalayas

Abstract

Hydrologically-induced shallow landslides represent severe threat to human life and infrastructure in the drainage basin of the largest river in northern Himalayas– the Yarlung Zangbo River Basin (YZRB). Shallow landslides in the cryosphere are jointly shaped by rainfall, glacier/snow melt and permafrost thaw, yet the relative contributions of these triggers remain unclear. Here we establish a mechanistic landslide triggering model for the YZRB and estimate that rainfall, glacier/snow melt and permafrost thaw contribute ~39.4%, 30.9%, and 29.7% to landslides, respectively, for the period 1991-2019. Future climate change will likely exacerbate landslide triggering, primarily due to increasing rainfall and permafrost thaw, whereas the contribution of glacier/snow melt decreases. The downstream YZRB is delineated as a hotspot for landslide triggering, but the middle stream is exposed to the greatest risk. This study yields new insights into landslide triggering mechanisms and provides guidelines for risk management in the Himalayas.