Moisture-Driven Landslides and Cascade Hazards in the Himalayan Region: A Synthesis on Predictive Assessment

Moisture-driven landslides (MDL), mainly caused by rain, seriously threaten lives and property, resulting in catastrophic damages and considerable economic losses. In areas with steep topography, the temporal and spatial clustering of long-duration, moderate-to-short-duration high-intensity rainfall contributes to landslides. Shifting precipitation patterns due to climate change, alterations to sub-surface conditions, such as pore-water pressures, retreating glaciers, and permafrost, further increase the risk of landslides. This synthesis apprises the physical drivers associated with MDLs and their complex interplay in triggering MDLs. The added value of this synthesis is multifaceted: (1) to uncover moisture-driven landslide trends and associated cascading hazards across the high-mountain areas of the globe (2) To explore the probability of rain-driven landslide-related mortality rate across different continents using the archived landslide information. (3) To present a systematic review of available physical and statistical tools to identify MDL triggers and highlight the need for updating rain thresholds using observed and projected climate information to address nonstationarities related to climate change and climate variability. Our analysis of archived rainfall-triggered landslides of the global landslide catalogue between 2007 and 2022 shows that global precipitation contributes to more than 60% of landslides. Further, our observational assessments of the fatality versus landslide frequency curves show that high-mountain Asia experiences the most frequent landslides, and its populations are especially vulnerable to such catastrophic events. The contribution of this synthesis paper is to inform scientists and practitioners of the latest developments in MDLs, aiding the translation of scientific understanding into developing resilience policies and adaptation efforts.