Forecasting the behaviour of complex landslides with a spatially distributed hydrological model

Abstract

Abstract. The relationships between rainfall, hydrology and landslide movement are often difficult to establish. In this context, ground-water flow analyses and dynamic modelling can help to clarify these complex relations, simulate the landslide hydrological behaviour in real or hypothetical situations, and help to forecast future scenarios based on environmental change. The primary objective of this study is to investigate the possibility of including more temporal and spatial information in landslide hydrology forecasting, by using a physically based spatially distributed model. Results of the hydrological and geomorphological investigation of the Super-Sauze earthflow, one of the persistently active landslide occurring in clay-rich material of the French Alps, are presented. Field surveys, continuous monitoring and interpretation of the data have shown that, in such material, the groundwater level fluctuates on a seasonal time scale, with a strong influence of the unsaturated zone. Therefore a coupled unsaturated/saturated model, incorporating Darcian saturated flow, fissure flow and meltwater flow is needed to adequately represent the landslide hydrology. The conceptual model is implemented in a 2.5-D spatially distributed hydrological model. The model is calibrated and validated on a multi-parameters database acquired on the site since 1997. The complex time-dependent and three-dimensional groundwater regime is well described, in both the short-and longterm. The hydrological model is used to forecast the future hydrological behaviour of the earthflow in response to potential environmental changes.

A model of hydrological and mechanical feedbacks of preferential fissure flow in a slow-moving landslide

“…The main difficulties stem from spatial and temporal heterogeneity of bedrock geometry, material layering, hydrological material properties and dominant hydrological processes across the landslide (Malet et al, 2005;Krzeminska et al, 2013). This is particularly true when dealing with slow-moving clayey landslides, where the continuous movement of the sliding material results in fissure formation with successive opening and closing of fissure apertures.…”

“…2d). The heterogeneity of the material and local surface mass movement processes (e.g., small surface mudflow accumulation lobes, local runoff wash deposits) explain important variations of porosity (from 0.33 to 0.49) and vertical hydraulic conductivity (from 10 −8 to 1.8 × 10 −5 m s −1 ) over the area (Malet, 2003;Malet et al, 2005).…”

Analysis of a landslide multi-date inventory in a complex mountain landscape: the Ubaye valley case study

“…The climate is controlled by both Mediterranean and mountain influences (Malet et al, 2005a), with a clear monthly rainfall variability (734 ± 400 mm for the period 1928-2013), significant daily temperature range (> 20 • C), more than 120 days of freezing per year (on average), long dry periods (from May to October) and the occurrence of summer rainstorms (with rainfall intensity up to 60 mm h −1 ).…”

“…Numerous studies were conducted for the analysis of mass movements (Flageollet et al, 1999;Malet et al, 2005a;Maquaire et al, 2003;Razak et al, 2011;Remaître et al, 2005;Thiery, 2007;Thiery et al, 2014) and several landslide types were mapped and analysed along the slopes (Fig. 1a).…”

Simulating the water content and temperature changes in an experimental embankment using meteorological data

“…This is quite common practice in the field of agronomy. In the field of geological and geotechnical engineering, this approach has been introduced recently but has been met quick development (Wilson et al 1994, Terlien et al 1995, Van Beek and Van Asch 1998, Bogaard and Van Asch 2002, Cui et al 2005, Malet et al 2005, Zornberg and McCartney 2005, Cui and Zornberg 2008.…”