A linked geomorphological and geophysical modelling methodology applied to an active landslide

Abstract

Moisture-induced landslides are a global geohazard; mitigating the risk posed by landslides requires an understanding of the hydrological and geological conditions present within a given slope. Recently, numerous geophysical studies have been attempted to characterise slow-moving landslides, with an emphasis on developing geoelectrical methods as a hydrological monitoring tool. However, landslides pose specific challenges for processing geoelectrical data in long-term monitoring contexts as the sensor arrays can move with slope movements. Here we present an approach for processing long-term (over 8 years) geoelectrical monitoring data from an active slow-moving landslide, Hollin Hill, situated in Lias rocks in the southern Howardian Hills, UK. These slope movements distorted the initial setup of the monitoring array and need to be incorporated into a time-lapse resistivity processing workflow to avoid imaging artefacts. We retrospectively sourced seven digital terrain models to inform the topography of our imaging volumes, which were acquired by either Unmanned Aerial Vehicle (UAV)-based photogrammetry or terrestrial laser ranging systems. An irregular grid of wooden pegs was periodically surveyed with a global position system, from which distortions to the terrain model and electrode positions can be modelled with thin plate splines. In order to effectively model the time-series electrical resistivity images, a baseline constraint is applied within the inversion scheme; the result of the study is a time-lapse series of resistivity volumes which also incorporate slope movements. The workflow presented here should be adaptable for other studies focussed on geophysical/geotechnical monitoring of unstable slopes.

Time-Lapse Electrical Resistivity Tomography (TL-ERT) for Landslide Monitoring: Recent Advances and Future Directions

“…The TL-ERT data inversion must also consider the effect of the temperature in the first layers of the subsoil and, in active landslides, the effect of the electrode's movement. Corrective formulas have been introduced for both critical issues [78,84].…”

Ground and Satellite-Based Methods of Measuring Deformation at a UK Landslide Observatory: Comparison and Integration

“…Periods of elevated soil moisture content induced by sustained effective rainfall, typically during the winter months (spanning from December to March in the UK) can trigger motion on the landslide in the order of centimetres to tens of centimetres [11]. In contrast, heavy/extreme isolated rainfall events occurring in periods of low antecedent moisture are not associated with movement on the slope [15].…”

“…In 2020 the ALERT system was replaced by a PRIME system [25]. The ERT measurements are also adjusted so that the movement of the pegs with the landslide is taken into account when modelling the resistivity in the subsurface [15]. Additionally, measurements of temperature, humidity, precipitation, solar radiation, wind speed and volumetric water content are being continuously recorded by a weather station from the UK Cosmic-Ray Soil Moisture Observing System (COSMOS, https://cosmos.ceh.ac.uk/ accessed on 8 June 2022) network [26,27].…”

“…In this paper, we present a case study of the Hollin Hill Landslide Observatory (HHLO) (Figure 1), where the British Geological Survey has developed and established groundbased geophysical monitoring systems [10,11], supplemented with ground-based geotechnical and displacement sensors and airborne (drone and conventional aircraft) repeated surveys. The Hollin Hill landslide is one of the best studied slow-moving landslides in the world (e.g., [12][13][14][15]) and the available ground-based measurements make it an exceptional location to study the InSAR measurements in comparison with the established ground truth data. We compare these geophysical and displacement data from the ground that we consider ground truth with InSAR displacement and velocity results derived from satellitebased Sentinel-1 measurements, and interpret them together to study the behaviour of this landslide.…”

Landslide Risk Assessment Using Granular Fuzzy Rule-Based Modeling: A Case Study on Earthquake-Triggered Landslides

“…The majority of the landslide events are water-induced where the natural and human related water activities reduced the slope stability and induced slope failures [1]. Data-driven approaches to manage the landslides are becoming more popular in recent years as they necessarily characterize the landslides both internally and externally [2]. The external characteristics of landslides are often geomorphology related such as distance to rivers, distance to road, elevation, and slope.…”