The effect of soil–vegetation–atmosphere interaction on slope stability: a numerical study

Abstract

The stability of a dike is influenced strongly by its water content, by way of changes in effective stress and weight. While flow through porous media is relatively well understood, water flux in and out of a dike through a vegetated surface is not as well understood. This paper presents a numerical study of the soil–vegetation–atmosphere interaction and discusses how it influences the stability of dikes covered with grass. A crop model was used to simulate vegetation growth and infiltration in response to meteorological forcing. The PLAXIS finite-element method model was used to simulate the impact of this infiltration on hydromechanical behaviour and dike stability. Results from a 4-year analysis indicated a strong correlation between root zone water content (WC rz) and factor of safety, although the relationship is not unique. The leaf area index (LAI) was also found to have a strong, lagged correlation with the water flux into the dike. This suggests that monitoring LAI could be a useful tool to identify vulnerable locations along dikes. It is therefore proposed that vegetation and root zone water content could be used as an indication to detect vulnerable dikes in the early stage.

Use of displacement as a proxy for dike safety

“…3b. The sudden decrease in LAI shows mowing events on 15 June and 15 August which were imposed in the crop model based on the mowing schedule for regional dikes in the Netherlands (Jamalinia et al, 2019a). The presence of cracks decreases the rate of LAI growth after mowing, because some precipitation drains directly to the lower soil layer via cracks leading to a reduction in the maximum stored water (seen in Fig.…”

“…In recent studies, e.g. Cundill et al (2013), Özer et al (2019) and Jamalinia et al (2019a), it has been proposed that Earth Observation (EO) can be a useful tool for increasing the efficiency, objectivity and coverage of dike inspection of vulnerable areas to be identified for detailed studies. Here, the displacement of an example vegetated dike under variable climatic conditions is studied, to investigate how measuring displacement would help dike managers detect vulnerable areas along dikes.…”

“…Geometry representing boundary, root zone layers, and points in which following results are plotted (afterJamalinia et al, 2019a).…”

A Data-Driven Surrogate Approach for the Temporal Stability Forecasting of Vegetation Covered Dikes

“…Our recent studies [36,41] show that transient surface displacement and vegetation condition have strong correlations with the slope FoS, due to their correlation with the moisture content of the slope. In those numerical studies, the meteorological data combined with soil parameters were used as input for the model to estimate the change in FoS and the non-linear hydro-mechanical behaviour of a dike under various weather and vegetation conditions.…”

“…There are in situ monitoring systems, such as electrical resistivity tomography, by which the dike condition can be assessed through, for instance, crack openings and water infiltration [35]. In the Netherlands, the current monitoring methods of dikes usually consist of infrequent (typically twice per year for regional dikes [36]) ground-based visual inspections, which rely highly on expert judgement. Thanks to (low cost or free) satellite images that have become available in recent years, there is a potential to use large (global) data sets to inspect slopes from space.…”