Process identification at a slow-moving landslide in the Vorarlberg Alps

Abstract

Abstract:A fine-grained slope that exhibits slow movement rates was investigated to understand how geohydrological processes contribute to a consecutive development of mass movements in the Vorarlberg Alps, Austria. For that purpose intensive hydrometeorological, hydrogeological and geotechnical observations as well as surveying of surface movement rates were conducted during 1998-2001. Subsurface water dynamics at the creeping slope turned out to be dominated by a three-dimensional pressure system. The pressure reaction is triggered by fast infiltration of surface water and subsequent lateral water flow in the south-western part of the hillslope. The related pressure signal was shown to propagate further downhill, causing fast reactions of the piezometric head at 5Ð5 m depth on a daily time scale. The observed pressure reactions might belong to a temporary hillslope water body that extends further downhill. The related buoyancy forces could be one of the driving forces for the mass movement. A physically based hydrological model was adopted to model simultaneously surface and subsurface water dynamics including evapotranspiration and runoff production. It was possible to reproduce surface runoff and observed pressure reactions in principle. However, as soil hydraulic functions were only estimated on pedotransfer functions, a quantitative comparison between observed and simulated subsurface dynamics is not feasible. Nevertheless, the results suggest that it is possible to reconstruct important spatial structures based on sparse observations in the field which allow reasonable simulations with a physically based hydrological model.

Modeling Macroporous Soils with a Two-Phase Dual-Permeability Model

“…A detailed description of the Heumöser slope can be found in Lindenmaier et al (2005), Lindenmaier (2008) and Wienhöfer et al (2009). An essential characteristic of the slope is that macropores and soil pipes are able to generate fast breakthrough curves of a tracer at a spring and on a cut-bank near a hiking trail (see Fig.…”

A novel explicit approach to model bromide and pesticide transport in connected soil structures

“…Preferential flow processes are highly relevant in runoff generation at the hillslope (Lindenmaier et al, 2005;Weiler and McDonnell, 2007;Wienhöfer et al, 2009;Zehe and Sivapalan, 2009) and headwater scales (Zehe and Blöschl, 2004;Zehe et al, 2005;2006) and consequently are a prime cause for the spatial variability in soil water content at hillslope scale (De Lannoy et al, 2006;Zehe et al, 2010b). Originally, the term "preferential flow" was coined after realising that water flow and transport in soils containing noncapillary structures -often worm burrows, root channels or soil cracks -was much faster than could be expected from classical theory of flow and transport in porous media (Beven and Germann, 1982;Zehe and Flühler, 2001).…”

Seismic monitoring of precursory fracture signals from a destructive rockfall in the Vorarlberg Alps, Austria

“…van Asch et al, 1999;Tsaparas et al, 2002). The direct coupling of rainfall, fast water infiltration, rise of pore water pressure in the subsurface and higher displacements on the slope's surface was observed by, for example, Lindenmaier et al (2005), Travelletti et al (2008) and Malet et al (2005) on different soft rock-landslides. The challenge in understanding the hydrologic control of the behavior of landslides is the implication of the heterogeneity of the respective landslide body in numerical models (e.g.…”