Quantifying the contribution of matric suction on changes in stability and displacement rate of a translational landslide in glaciolacustrine clay

Abstract

A study of factors impacting landslide displacement rates was conducted on the Ripley Landslide within the Thompson River valley in British Columbia, Canada for the International Programme on Landslides' project #202. Seasonal and multiyear changes in atmospheric factors cause cyclic fluctuation of matric suction in the vadose zone through changes to the in-situ water content. The ingress of moisture is shown to contribute to multiyear and seasonal loss of stability causing increasing landslide displacement rates, often disregarded in slope stability calculations. However, the water content in the unsaturated zone is important, especially in semi-arid to arid climates where the water table is low and large portions of the slope are unsaturated. Additional tools for studying long-term variations in climate and seasonal changes in water content are presented. These tools are used to characterize historical climate and compare several factors that have resulted in changing landslide displacement rates and magnitude. Infiltration of precipitation and snowmelt directly contributes to matric suction loss in the head scarp and is exacerbated by the presence of tension cracks. While groundwater levels are often correlated to changing displacement rates, changes in matric suction can also influence the rates of displacement. Climatic trends over subsequent years alter the long-term soil water accumulation which impacts rates of landslide displacement. By accounting for additional strength, or potentially a loss in strength due to increasing water content, it is possible to develop a more complete understanding of the mechanisms of climate change which drive displacement rates in the translational, metastable earthen slides that dominate the Thompson River valley. These mechanisms can be applied to comparable river valleys around the world.

Benchmarked RADARSAT-2, SENTINEL-1 and RADARSAT Constellation Mission Change-Detection Monitoring at North Slide, Thompson River Valley, British Columbia: ensuring a Landslide-Resilient National Railway Network

“…Combined, these geospatial technologies provide the contextual information required for understanding the influence of surficial geology and internal structure of monitored slopes, and external climate-driven variables (e.g., air temperature, precipitation, river level, groundwater levels) on landslide activity (cf. Holmes et al 2020;Huntley et al 2020;Sattler et al 2021).…”

“…Landslides in the Thompson River valley serve as field laboratories to test and compare the reliability and effectiveness of different static, dynamic, and real-time monitoring technologies (e.g., Holmes et al 2020;Huntley et al 2016Huntley et al , 2019aHuntley et al , 2019bJournault et al 2018;Sattler et al 2021). These research activities are an important component of the International Consortium on Landslides (ICL) International Programme on Landslides (IPL) Project 202 (Bobrowsky et al 2017).…”

Long-term geoelectrical monitoring of landslides in natural and engineered slopes

“…There was an average of 89.5 mm of downslope displacement in the main sliding mass over the monitoring period, and the greatest rate of movement occurred between October and April each year. When the Thompson River level is low because of freezing precipitation, this leads to a debuttressing effect, and when suction levels decrease at the onset of snowmelt, the slope is vulnerable to failure and movement accelerates until the river level rises again in response to snowmelt in the wider Thompson River Valley (Sattler et al, 2021).…”

The Use of Soil Moisture and Pore-Water Pressure Sensors for the Interpretation of Landslide Behavior in Small-Scale Physical Models

“…For example, numerical modelling has been successfully used to investigate how different factors affect the stability of both shallow (e.g., [ 1 , 7 , 8 , 10 , 16 , 17 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ]) and deep-seated landslides under different rainfall conditions (e.g., [ 19 , 43 , 44 , 45 , 46 , 47 , 48 ]). Field monitoring has been successfully used to observe the hydraulic and mechanical performance of slopes in different geological and climatic contexts (e.g., [ 7 , 17 , 21 , 22 , 31 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 ]). Particularly valuable data have been obtained from field experiments conducted on instrumented slopes subjected to increasing soil moisture conditions using rainfall simulators or controlled water inflows from trenches ...…”