A modified tank model including snowmelt and infiltration time lags for deep-seated landslides in Alpine Environments (Aggenalm, Germany)
W. Nie1, M. Krautblatter1, K. Leith1, K. Thuro2, and J. Festl31Landslide Research, Faculty of Civil Geo and Environmental Engineering, Technische Universität München, Munich, Germany 2Engineering Geology, Faculty of Civil Geo and Environmental Engineering, Technische Universität München, Munich, Germany 3Baugeologisches Büro Bauer GmbH, Domagkstraße 1a, 80807 München, Germany
Received: 15 Dec 2015 – Accepted for review: 22 Dec 2015 – Discussion started: 18 Jan 2016
Abstract. Deep-seated landslides are an important and widespread natural hazard within alpine regions, and can have a massive impact on infrastructure. Pore water pressure plays an important role in determining the stability of hydro-triggered deep-seated landslides. We improve current methods of groundwater level prediction by introducing a means to account for time lags associated with groundwater supply caused by snow accumulation, snowmelt, and infiltration in deep-seated landslides. In this study, we demonstrate a simple method to improve the estimation of these time lags using a modified tank model to calculate groundwater levels. In a deep-seated landslide in Bavaria, Germany, our results predict daily changes in pore water pressure ranging from -1 to 1.6 kPa depending on daily rainfall and snowmelt. The inclusion of time lags improves the results of standard tank models by ~36% (linear correlation with measurement) after heavy rainfall and, respectively, by ~82% following snowmelt in a 1-2 day period. For the modified tank model, we introduced a representation of snow accumulation and snowmelt, based on a temperature index and an equivalent infiltration method, i.e. the melted snow water equivalent. This compares well to the in situ measurement for the same time interval which reflect changes of pore water pressure with 0-8% relative error in rainfall season (standard tank model: 2-16% relative error) and with 0-7% relative error in snowmelt season (standard tank model: 2-45% relative error). Here we demonstrate a modified tank model for deep-seated landslides that includes snow and infiltration effects and can effectively predict changes in pore water pressure in alpine environments.
Nie, W., Krautblatter, M., Leith, K., Thuro, K., and Festl, J.: A modified tank model including snowmelt and infiltration time lags for deep-seated landslides in Alpine Environments (Aggenalm, Germany), Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2015-341, in review, 2016.