Journal Article

Human Settlement Pressure Drives Slow‐Moving Landslide Exposure

Hürlimann, Marcel, Marwan, Norbert, Köhler, Lisa, Zhao, Chaoying, Pánek, Tomáš, Zhang, Yi, Handwerger, Alexander L., Demurtas, Valentino, Samprogna Mohor, Guilherme, Tsou, Ching‐Ying, Ferrer, Joaquin V., Thieken, Annegret H., Urgilez Vinueza, Alexandra, Dewitte, Olivier, Teshebaeva, Kanayim, Kurths, Jürgen, Korup, Oliver, Reyes‐Carmona, Cristina

2024

Overview

A rapidly growing population across mountain regions is pressuring expansion onto steeper slopes, leading to increased exposure of people and their assets to slow‐moving landslides. These moving hillslopes can inflict damage to buildings and infrastructure, accelerate with urban alterations, and catastrophically fail with climatic and weather extremes. Yet, systematic estimates of slow‐moving landslide exposure and their drivers have been elusive. Here, we present a new global database of 7,764 large (A ≥ 0.1 km2) slow‐moving landslides across nine IPCC regions. Using high‐resolution human settlement footprint data, we identify 563 inhabited landslides. We estimate that 9% of reported slow‐moving landslides are inhabited, in a given basin, and have 12% of their areas occupied by human settlements, on average. We find the density of settlements on unstable slopes decreases in basins more affected by slow‐moving landslides, but varies across regions with greater flood exposure. Across most regions, urbanization can be a relevant driver of slow‐moving landslide exposure, while steepness and flood exposure have regionally varying influences. In East Asia, slow‐moving landslide exposure increases with urbanization, gentler slopes, and less flood exposure. Our findings quantify how disparate knowledge creates uncertainty that undermines an assessment of the drivers of slow‐moving landslide exposure in mountain regions, facing a future of rising risk, such as Central Asia, Northeast Africa, and the Tibetan Plateau. Plain Language Summary Slow‐moving landslides can damage buildings and infrastructure, while potentially leading to thousands of fatalities with a sudden collapse. As populations expand in mountain regions, more communities settling into steeper terrain could be exposed to landslide‐prone areas. Yet, our estimates of populations exposed to landslides excludes slow‐moving landslides. We address this by identifying unstable slopes, inhabited by human settlements, from a new global database of 7,764 reported large slow‐moving landslides located in nine IPCC mountain‐risk regions. Across most regions, we find that landslide exposure increases with sprawling urbanized areas, though clearly not with steeper terrain. We show regional contrasts in how exposure to floods may drive people to settle on unstable slopes. East Asia stands out in how landslide exposure increases in more urbanized basins with gentler slopes and less flood exposure. Our results indicate that communities in mountain regions, facing increasing future landslide and flood risk, have the least certain insight on slow‐moving landslide exposure and their drivers. Key Points We present a database of 7,764 reported large (A ≥ 0.1 km2) slow‐moving landslides in nine IPCC regions and find 563 are inhabited We learn more about landslide exposure from regional responses to flood exposure than from an abundance of slow‐moving landslides Urbanization in basins can be a relevant driver of landslide exposure, while steepness and flood exposure have varying regional influences

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: Africa / Asia / Basins / Bayesian inference / Building damage / Climate change / Drainage / Environmental aspects / Exposure / Extreme weather / Floods / Human settlements / Infrastructure / Land settlement / landslide exposure / Landslides / Landslides & mudslides / Mountain regions / Mountains / natural hazards / Population / Regions / Slope stability / Slopes / slow‐moving landslides / Social aspects / Urbanization / Watersheds