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In-situ geophysical and hydrochemical monitoring of landslide dynamics (Pégairolles, Languedoc, France)

2018; Linguagem: Inglês

10.3997/2214-4609.201800434

2214-4609

Philippe Pézard, Stéphanie Gautier, N. Denchik, Muriel Geeraert, Gilles Henry,

Tree Root and Stability Studies

Summary This paper focuses on the relationship between rainfalls, groundwater flow and in-situ deformation within a landslide body. In relation to more traditional surface measurements, a set of innovative, in-situ and high-frequency monitoring techniques of both hydrochemical and geophysical processes has been deployed in two nearby shallow boreholes. The experimental site is located near Lodève at Pegairolles de l'Escalette, Languedoc (France), an hour west of Montpellier. In this region, the deformation process is linked to intense climatic events such as torrential rains (Cevenol events) and the associated dissolution of evaporites. With a relatively simple geological context and a unique triggering factor, these landslides are natural observatories to study the impact of climatic events on slope processes. Downhole data collected over 5 years from the integrated set of permanent borehole instruments will be presented to illustrate the spatial and temporal dynamics of landslides processes near Lodève, shedding light on the relationships between rainfalls, ground water flow and deformation. The data recorded over time provide constraints to derive physical and numerical models describing the landslide hydrodynamic behavior. Also, the high-frequency monitoring may lead to the identification of geophysical proxys of deformation, which could be used as landslide precursors in the future.