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Four-dimensional imaging of moisture dynamics during landslide reactivation

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posted on 14.02.2017 by S. Uhlemann, J. Chambers, Paul Wilkinson, Hansruedi Maurer, A. Merritt, Philip Meldrum, Oliver Kuras, David Gunn, Alister Smith, Tom Dijkstra
Landslides pose significant risks to communities and infrastructure, and mitigating these risks relies on understanding landslide causes and triggering processes. It has been shown that geophysical surveys can significantly contribute to the characterization of unstable slopes. However, hydrological processes can be temporally and spatially heterogeneous, requiring their related properties to be monitored over time. Geoelectrical monitoring can provide temporal and volumetric distributions of electrical resistivity, which are directly related to moisture content. To date, studies demonstrating this capability have been restricted to 2-D sections, which are insufficient to capture the full degree of spatial heterogeneity. This study is the first to employ 4-D (i.e., 3-D time lapse) resistivity imaging on an active landslide, providing long-term data (3 years) highlighting the evolution of moisture content prior to landslide reactivation and showing its decline post reactivation. Crucially, the time-lapse inversion methodology employed here incorporates movements of the electrodes on the unstable surface. Although seasonal characteristics dominate the shallow moisture dynamics during the first 2 years with surficial drying in summer and wetting in winter, in the months preceding reactivation, moisture content increased by more than 45% throughout the slope. This is in agreement with independent data showing a significant rise in piezometric heads and shallow soil moisture contents as a result of prolonged and intense rainfall. Based on these results, remediation measures could be designed and early-warning systems implemented. Thus, resistivity monitoring that can allow for moving electrodes provides a new means for the effective mitigation of landslide risk.

Funding

The Natural Environment Research Council (NERC) supported this research.

History

School

  • Architecture, Building and Civil Engineering

Published in

Journal of Geophysical Research. Earth Surface

Citation

UHLEMANN, S. ...et al., 2017. Four-dimensional imaging of moisture dynamics during landslide reactivation. Journal of Geophysical Research. Earth Surface, 122(1), pp.398-418.

Publisher

AGU Publications © British Geological Survey (NERC)

Version

VoR (Version of Record)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Acceptance date

30/12/2016

Publication date

2017

Notes

This paper is also available at http://doi.org/10.1002/2016JF003983.

ISSN

2169-9003

Language

en

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