Climate change is affecting our lives in multiple ways. More frequent draughts or storms, wildfires, land use changes will alter the patterns and frequency of slope instability phenomena and, consequently, the risk they pose to populations, infrastructures, and ecosystems. The key to study the short-term response of slopes to climate change has always been a hydro-meteorological one – precipitation being a major trigger of landslides. Indeed, regional-scale studies generally focus on well-recognised triggers and controls (rainfall, seismic shaking, morphology, lithology). At the same time, they systematically neglect the possible role of thermal variables (Figure 1). In doing so, they disregard the direct effect of temperature on the hydro-mechanics of geomaterials or deem it insignificant.
In high-pressure and high-temperature domains, such as in seismic faults and slip zones of giant rock avalanches, thermo-hydro-mechanically coupled processes are well known and well investigated. These processes are also accounted for in specific engineering infrastructures, such as underground heat exchangers or deep geological repositories of radioactive waste.
However, laboratory experiments, demonstrate a significant dependence of hydro- mechanical properties on temperature (especially in clay-rich materials) even in ranges naturally experienced at the ground surface and in the near subsurface (Figure 2).
It is thus reasonable to hypothesise that temperature fluctuations and trends, propagating from the surface to the subsurface, may exert a quantifiable, direct effect on the stability of slopes (Figure 3), the kinematics of landslides, and, in the long term, the erosion rates.
In ongoing and proposed projects (GA ČR, MSCA, MSCA-IV), we are tackling the problem at multiple scales and in a variety of geomaterials, with a particular focus on the geomechanic role of temperature in mild climates. In the laboratory, we are performing or will perform temperature controlled experiments to relate physical (e.g., porosity, mineralogy) and thermal properties (e.g., heat capacity, irradiance, cooling rates) with changes in permeability, volume and strength under climatic (heating-cooling, wetting-drying) and mechanical (loading-unloading) forcing. In modelling environment, we plan to analyse the stability of slopes using a fully coupled thermo-hydro-mechanical approach. In the field, we are going to perform comprehensive monitoring (including remote, surface and in-borehole measurements of temperature and moisture) at selected sites affected by slope instability, to gain insight into the dominant physical / thermodynamic processes controlling landsliding. We wish to complete the picture by investigating, over larger areas, whether the role of temperature, so evident in a controlled laboratory environment, can emerge and be significant in regional studies. At the same time, we wish to develop physically-based tools, stemming from the advanced coupled models available at smaller scales, to demonstrate the significance/insignificance of temperature effects in complex, heterogeneous landscapes.
Within this framework, the proposed postdoctoral project aims at investigating, through geostatistical and physically-based modelling, the role of temperature and other thermal variables on the patterns and trends of landslides in various soil and rock types at catchment/regional scale in mild climates. The ideal candidate will have strong analytical and computational skills and be familiar with geographical information software environment (including machine learning algorithms and satellite/UAV data processing) but also with advanced constitutive and numerical modelling of geomaterials. This way, the candidate will be able to propose and implement upscaling strategies linking results on laboratory samples all the way to catchment/regional studies. Potentially, this project can yield more reliable landslide risk scenarios in the light of climate change.
Figure 1. Frequency of thematic variables in landslide susceptibility modelling (data set: 565 models published in 1983–2016). Note the low frequency of geotechnical and climatic variables. Within them, temperature is never accounted for explicitly. Legend: EO, Earth observation; GEOM, geomorphological; GEOT, geotechnical; LR, landslide related; OA, other anthropic; OC, other climatic; SE, seismic (mod from. Reichenbach et al., 2018, doi: 10.1016/j.earscirev.2018.03.001).
Figure 2. An example of thermal response on the residual shear strength of a smectite-rich soil, indicating a beneficial effect of temperature on slope stability, in this case (mod. from Shibasaki et al., 2017, doi: 10.1002/2016JB013241).
Figure 3. Climate change, thermo-hydro-mechanical coupling, landsides: a conceptual sketch of multi-scale interaction.
Funding and project approval:
Required application materials:
How to submit application materials:
Please send email with the required application materials to dr. Gianvito Scaringi: email@example.com, Faculty of Science, Charles University, Prague.
The application deadline is July 23, 2021.
For more information please visit the webpage of the JUNIOR Fund project of the Charles University.