91ÌÒÉ«

We develop numerical methods and models to understand how vegetation and climate influence the mechanical and hydraulic behaviour of soils, with direct implications for the safety and serviceability of geotechnical infrastructure. Seasonal pore water pressure variations—driven by rainfall infiltration and plant evapotranspiration—are among the most important and least well-understood drivers of slope instability, foundation movement, and infrastructure deterioration in the UK and beyond. Our research brings together advanced coupled flow–deformation modelling, ecohydrological representations of vegetation, and climate change projections to address this challenge.

Vegetation Management and Slope Stability

A central application of our SPAI research concerns vegetated infrastructure slopes, where both the presence and removal of trees and shrubs directly affect pore water pressures and, in turn, stability and serviceability. presented a three-dimensional numerical study in the Canadian Geotechnical Journal examining different vegetation management strategies for a cut slope covered in trees and suffering serviceability problems. The study compared patterns of tree removal and replacement with shrubs, demonstrating that replacement is generally preferable to clearance: removing vegetation without substitution can have detrimental effects on both stability and serviceability, while strategically replanting with lower-water-demand species maintains hydraulic reinforcement through root-water extraction. This work provides the first fully three-dimensional treatment of vegetation management that considers stability and serviceability simultaneously.

Earlier conference contributions examined the three-dimensional effects of soil-atmosphere interaction on infrastructure slope stability more broadly () and investigated how poorly constrained permeability — including its variation with suction and its response to desiccation cracking — affects predictions of pore water pressure under atmospheric loading.

Coupling Ecohydrology with Geotechnical Modelling

A key strand of our SPAI research is improving how vegetation-driven water exchange is represented in geotechnical analysis. introduced a coupled methodology in Geomechanics for Energy and the Environment that links ecohydrological modelling with geotechnical finite element analysis and validates the approach against field monitoring data from a cut slope in Newbury, UK. Building on that framework, the new 2026 study shows that modelling choices in atmospheric boundary conditions can materially change predictions of pore water pressure, factor of safety, and serviceability. In particular, it shows that daily fluxes retain drying–wetting variability that monthly aggregation smooths out, that a seasonally varying static leaf area index can approximate fully dynamic vegetation for many design applications, and that modelling transpiration as root water uptake distributed with depth can significantly alter predicted suctions and stability for deeper-rooted vegetation.

provides further practical guidance on when these simplifications are appropriate. For preliminary design, a simplified approach using monthly rates, surface-only boundary conditions, and static seasonal vegetation may be sufficient to capture broad trends conservatively. For final design, monthly rates with dynamic vegetation and surface boundary conditions may offer a good balance between realism and computational cost. For early warning and back-analysis, however, the paper recommends daily atmospheric forcing together with internal boundary conditions that distribute transpiration through the root zone, especially where climate change, deep-rooted vegetation, or serviceability concerns make pore pressure variations more sensitive to modelling assumptions. Taken together, this work shows not only how to couple ecohydrology and geotechnics, but which aspects of that coupling matter most for different engineering decisions.

Engineered Barriers for Climate Adaptation

In parallel with the slope stability work, our research has contributed to the EPSRC-funded CACTUS (Climate Adaptation Control Technologies for Urban Spaces) project, a six-university collaboration running from 2018 to 2023. 91ÌÒÉ«'s contribution focused on developing design protocols for engineered composite barrier systems intended to limit the impact of extreme rainfall and long-term climate change on urban geotechnical infrastructure. We assessed the effectiveness of proposed barriers with modified hydraulic properties — including vegetated permeable layers and capillary break layers — under current and future UK weather patterns, and extended the code's capabilities to model freeze-thaw alongside drying-wetting cycles. Related work by demonstrated the potential of engineered soil barriers to minimise annual shrinkage and swelling in plastic clays, addressing a problem responsible for over £1.6 billion of damage to UK infrastructure during drought years.

Full set of publications and open datasets are available through our Publications page and the .