Integration of root systems into a GIS-based slip surface model: computational experiments in a generic hillslope environment

Abstract

Integration of root systems into a GIS-based slip surface model: computational experiments in a generic hillslope environment Abstract Root systems of trees reinforce the underlying soil in hillslope environments and therefore potentially increase slope stability. So far, the influence of root systems is disregarded in Geographic Information System (GIS) models that calculate slope stability along distinct failure plane. In this study, we analyse the impact of different root system compositions and densities on slope stability conditions computed by a GIS-based slip surface model. We apply the 2.5D slip surface model r.slope.stability to 23 root system scenarios imposed on pyramidoid-shaped elements of a generic landscape. Shallow, taproot and mixed root systems are approximated by paraboloids and different stand and patch densities are considered. The slope failure probability (P f ) is derived for each raster cell of the generic landscape, considering the reinforcement through root cohesion. Average and standard deviation of P f are analysed for each scenario. As expected, the r.slope.stability yields the highest values of P f for the scenario without roots. In contrast, homogeneous stands with taproot or mixed root systems yield the lowest values of P f . P f generally decreases with increasing stand density, whereby stand density appears to exert a more pronounced influence on P f than patch density. For patchy stands, P f increases with a decreasing size of the tested slip surfaces. The patterns yielded by the computational experiments are largely in line with the results of previous studies. This approach provides an innovative and simple strategy to approximate the additional cohesion supplied by root systems and thereby considers various compositions of forest stands in 2.5D slip surface models. Our findings will be useful for developing strategies towards appropriately parameterising root reinforcement in real-world slope stability modelling campaigns.

The influence of climate change and canopy disturbances on landslide susceptibility in headwater catchments

“…The root system of trees increases the resistance of soils against shallow landslides (c.f. Cohen and Schwarz, 2017;Ghestem et al, 2011;Schmaltz and Mergili, 2018;Schwarz et al, 2015). Following the approach of our slope stability model, the rooting of the soil acts as an additional cohesion force.…”

Root Reinforcement in Slope Stability Models: A Review

“…The analysis of the data they collected confirms that the presence of forest on the slope can be reasonably considered as a key factor in terms of stability, especially in steep slopes-more than 35 • of gradient-and underlines the importance of the forest structure characteristics such as spacing between trees and dimension of gaps among vegetation. Schmaltz and Mergili (2018) [113] conducted a sensitivity analysis of the slope stability to different forest stand configurations and density of root systems. Using a GIS-based slip surface model, they tested 23 different root system scenarios and a generic hillslope landscape combining configurations of roots-shallow, taproot, mixed-with different stand and patch densities, and considering different size of potential shallow slip surfaces.…”

“…Measures on Roots Roots Modeling Slope or Smaller Scale SSM Basin or Larger Scale SSM Other Abdi et al 2018 [49] x Arnone et al 2016 [87] x x Bordoni et al 2020 [102] x x x Bordoni et al 2016 [100] x x Chiaradia et al 2016 [104] x x x Chok et al 2015 [36] x x Cislaghi et al 2017 [101] x x Cislaghi et al 2017 [85] x x x Cislaghi et al 2018 [86] x Cislaghi et al 2019 [114] x x x Cuomo et al 2020 [91] x Dazio et al 2018 [57] x x Gehring et al 2019 [121] x x Giadrossich et al 2017 [48] x Gonzalez-Ollauri 2017 [99] x x x Hales et al 2018 [82] x x Hales and Miniat 2017 [43] x x x Hwang et al 2015 [81] x x x Kokutse et al 2016 [35] x x Likitlersuang et al 2017 [106] x Masi et al 2020 [70] x Moos et al 2016 [111] x x x Rickli et al 2019 [112] x Rossi et al 2017 [107] x Saadatkhah et al 2016 [93] x x Salvatici et al 2018 [89] x Schmaltz and Mergili 2018 [113] x x Schmaltz et al 2019 [116] x x Switala and Wu 2018 [95] x Switala and Wu 2019 [97] x Vergani et al 2017 [11] x Vergani et al 2017 [118] x x Vergani et al 2015 [21] x x Wang et al 2017 [105] x x x Wang et al 2018 [117] x x Wang et al 2019 [103] x In the last few years, a challenging research trend emerged in the field of slope stability modelling: the progressive widening of application areas from slope to catchment and regional scale-i.e., over dozens or hundreds of squared kilometer-wide areas. Although advances made in the modelling of the mechanica...…”

“…Plants are complex organisms highly interacting with atmosphere, hydrosphere, lithosphere, and biosphere so that the aspects interesting for slope stability are countless and even some potentially very significative ones such as the influence of forest structure, wildfires, and soil moisture gradient have been considered or deepened only recently [43,[111][112][113][114][115][116][117][118][119][120][121]. The research that dealt with the effects of forest structure variables on slope stability such as gap length or distances between trees [111][112][113][114][115] highlighted that these factors are not negligible in order to contain the landslide hazard and that, therefore, should be taken into account by forest management operators. Despite wildfires is a worldwide common and highly destructive factor of disturbance for vegetation, quantitative data on the impact on root reinforcement and its post-fire evolution are still scarce.…”

Stability Analysis of Ecological Slopes Based on a 3D Finite Element Model

“…In the modeling process, the construction of plant root units and the choice of root-soil contact types will determine the calculation accuracy of the model [26]. ere are mainly four modeling methods that are widely used at present: (1) regardless of the morphology of the plant root system, the plant and soil are regarded as composite materials, and attributes are given as a whole; (2) the interaction between the plant and the soil is converted into a load, which is directly applied to the soil element; (3) the soil and root models are built separately, assuming that the deformation between the two can be automatically coordinated; (4) while separating the root system of the plant and the soil, the relative movement of the two is restricted by setting the contact method between the two [27][28][29][30].…”