Abstract

Abstract. Controls on landsliding have long been studied, but the potential for landslide-induced dam and lake formation has received less attention. Here, we model possible landslides and the formation of landslide dams and lakes in the Austrian Alps. We combine a slope criterion with a probabilistic approach to determine landslide release areas and volumes. We then simulate the progression and deposition of the landslides with a fluid dynamic model. We characterize the resulting landslide deposits with commonly used metrics, investigate their relation to glacial land-forming and tectonic units, and discuss the roles of the drainage system and valley shape. We discover that modeled landslide dams and lakes cover a wide volume range. In line with real-world inventories, we further found that lake volume increases linearly with landslide volume in the case of efficient damming – when an exceptionally large lake is dammed by a relatively small landslide deposit. The distribution and size of potential landslide dams and lakes depends strongly on local topographic relief. For a given landslide volume, lake size depends on drainage area and valley geometry. The largest lakes form in glacial troughs, while the most efficient damming occurs where landslides block a gorge downstream of a wide valley, a situation preferentially encountered at the transition between two different tectonic units. Our results also contain inefficient damming events, a damming type that exhibits different scaling of landslide and lake metrics than efficient damming and is hardly reported in inventories. We assume that such events also occur in the real world and emphasize that their documentation is needed to better understand the effects of landsliding on the drainage system.

Highlights

  • Landslides are a major threat to human lives and infrastructure in mountain ranges worldwide

  • In the following result sections, we describe the 1057 simulated landslides and landslide-dammed lakes: their spatial distribution, their geometric characteristics, and their associated stability and obstruction indices

  • Most of the landslides are located in the western part of the study region, within high topography with significant relief occupied by glaciers during the Last Glacial Maximum (LGM)

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Summary

Introduction

Landslides are a major threat to human lives and infrastructure in mountain ranges worldwide. Beyond the direct hazard due to the moving mass, landslides can initiate natural hazard cascades by damming rivers and initiating catastrophic flash floods and debris flows (e.g., Costa, 1985; Costa and Schuster, 1988; Cui et al, 2009). Through such long-range effects, even unwitnessed landslides occurring in remote areas matter. Studies on the formation of landslide dams and lakes, and on its dependence on factors that influence topography, such as contributing drainage area of rivers at their damming location, geologic preconditioning and long-term climatic forcing, are scarce

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