Increasing rapid dry-wet transition intensifies global landslide risks

Kunlong He^1,2, Xiaohong Chen^1,2*, Chongyu Xu³, Amir AghaKouchak⁴*, 

Corresponding to: Xiaohong Chen, eescxh@mail.sysu.edu.cn and Amir AghaKouchak, amir.a@uci.edu

Abstract

Landslides are commonly triggered by extreme rainfall events, but the influence of preceding prolonged dry conditions followed by successive heavy rainfall, is a fundamental yet often unexplored risk factor in landslide risk assessment. Here we show a significant increase in the frequency of landslides triggered by dry-wet transitions, attributed to the heightened frequency and intensity of these transitions. The relationship between landslides and dry-wet transitions is more pronounced than with extreme precipitation alone, highlighting the need to consider antecedent dry conditions in landslide risk assessments. The occurrence frequency of dry-wet landslide is projected to increase in the future (2021-2100) by 39.2 ± 9% compare to the historical period (2001-2020) under the high emission scenarios of SSP585. The historical and projected dry-wet landslides occur primarily in the Alps, Himalayas, and Andes and Rocky Mountains. Specifically, dry-wet landslide occurrences are projected to increase by 13.8±1.4 times in North America, 11.5±1.2 times in the Middle East-Europe, and 1.7±0.4 times in high mountain regions in Asia, mainly the Himalayas and southwest China. Developing countries with large populations, such as South Africa, India, and China, are projected to face increased risks of dry-wet landslides due to unplanned land expansion under the future socioeconomic pathways. Our findings underscore the importance of considering the combined effects of successive dry and heavy precipitation in landslide risk assessments. We also highlight the urgent need to address exposure inequalities in low-income countries, providing key insights for developing mitigation and prevention strategies.