Global connections between El Nino and landslide impacts

Abstract:

El Nino is a critical part of global inter-annual and multi-annual climate variability, and the intensity of El Nino has major implications for rainfall-induced natural hazards in many vulnerable countries. Intense rainfall is a key trigger for rapid landslides, which lead to thousands of fatalities each year across the world. The loss of life and damage to infrastructure due to rainfall-triggered landslides is likely to be modulated by the strength of El Nino. However, while some case studies of El Nino impact on local landslide impacts exist, our knowledge of the distribution of impacts globally remains unconstrained.

In this study, we combine the new 20-year record of rainfall from NASA’s Global Precipitation Measurement IMERG (Integrated Multi-satellitE Retrievals for GPM) product with a global landslide exposure model to show that El Nino has far-reaching effects on landslide impacts to people and infrastructure. We model landslide hazard associated with intense rainfall each day for the 20-year record and the exposure of populations and critical infrastructure. We compare the 12-month moving average model values for exposure with relevant El Nino indices, and find that El Nino leads to significant variability in average exposure to landslide hazard. The modelled impact of El Nino on landslide exposure can be greater in parts of Southeast Asia and Latin America than the typical rainy-season to dry-season changes. These findings improve our understanding of hazard variability around the world and can assist disaster mitigation efforts on seasonal timescales.