Forecasting dam height and stability of dams formed by rock slope failures in Norway

Abstract

<jats:p>Abstract. Based on an inventory of 69 dams formed by rock slope failures in southwestern Norway and published landslide dam inventories from other parts of the World we developed semi-empirical relationships linking the maximum dam height (HD.max in m) to dam volume (VD in 106 m3) and other relevant parameters such as valley width (WV in m) or dam area (AD in km2). Power-laws are obtained for HD.max = f(VD) and HD.max = f(VD, WV), while a linear relationship links HD.max to the ratio VD / AD. For dams in southwestern Norway, the linear relationship HD.max = 1.75 × VD / AD has least uncertainties and provides best results when comparing predicted dam heights with a validation dataset composed of existing dams in northern Norway and numerically modelled dams for possible rock slope failures. To assess the stability of future dams we use the predicted dam heights in the dimensionless blockage index DBI and relating this index to the probability of dam failure derived from our dataset and other published databases on landslide dams. This study underlines the potential of semi-empirical relationships for assessing dam height and stability that needs to be included in preliminary hazard and risk assessment for unstable rock slopes, because damming of a river is an important secondary effect of landslides due to upstream flooding and possible outburst floods in case of dam failure. </jats:p>

Rock Avalanche-Generated Sediment Mass Flows: Definitions and Hazard

“…The definition of a distinct mass flow impact area is a unique feature of this system, and the three-zone system provides the basis for the general rock avalanche hazard assessment system we propose. This work is complementary to recent work on landslide dams (a Zone 3 impact in our classification system), where researchers have described global datasets of landslide dams with consistent attributes (Fan et al, 2020;Oppikofer et al, 2020).…”

Mass-Movements in Cold and Polar Climates

“…on glaciers and surrounding areas (e.g. Deline et al 2015b;Dufresne et al 2019;Hewitt et al 2011), in fjord environments were rock-slope failures can generate tsunamis (Böhme et al 2011;Kuhn et al 2019) and in valley systems were large rock-slope failures can dam rivers (Oppikofer et al, 2020;Strom and Korup, 2006).…”

“…As glacial environments are highly dynamic because of increasing atmospheric temperatures, the landslide hazard in these regions is more difficult to assess because of the changing zones of instability and initiation (e.g., Evans and Clague, 1988;Geertsema et al, 2006a,b;Kääb et al, 2005). The consequences of landslides in glacial environments can be more unexpected and severe than the events themselves, generating hazardous consequences because of dam-creation (Fan et al, 2020;Oppikofer et al, 2020;Strom and Korup, 2006), or tsunami if they reach the water (Dahl-Jensen et al, 2004;Dai et al, 2020;Dufresne et al, 2018a). A better understanding of changes in slope stability caused by the loss of glacier ice could improve the definition of landslide hazard zones, aiding to protect areas and populations exposed to these hazards (Haeberli et al, 2017b;Hock et al, 2019).…”

“…GLOFs are floods that originate from lakes formed behind a landslide dam (Fan et al, 2020;Oppikofer et al, 2020;Strom and Korup, 2006) or dammed by a frontal moraine or glacial ice (Carey et al, 2012;Clague and Evans, 2000;Cook et al, 2016;Haeberli et al, 2016;Harrison et al, 2018;Hubbard et al, 2005;Richardson and Reynolds, 2000;Veh et al, 2019;Westoby et al, 2014). The lakes can drain catastrophically for several reasons, including mass movements into the lake (Figure 9) (Costa and Schuster, 1988;Korup and Tweed, 2007).…”

Recent technological and methodological advances for the investigation of landslide dams

“…Fan et al, 2020 for review) or assessed by numerical modelling. Hungr (2011) examined the possibility of predicting landslide dam geometry using empirical, as well as 2D and 3D dynamic analyses of landslide runout, while other empirical methods to determine the landslide dam height have been proposed and compared to runout modelling (Oppikofer et al, 2020).…”