Abstract Soil–Plant-Atmosphere Interaction (SPAI) is an essential factor in slope behaviour, affecting water inflow and outflow, and thereby influencing Pore Water Pressures (PWP), soil strength and stiffness, and slope stability and serviceability. Due to its complexity, SPAI and its effect on slope behaviour are best described by hydro-mechanically coupled numerical analysis, rendering the boundary conditions (BC) used to replicate atmospheric conditions critical. Here, different considerations have been made regarding the temporal and spatial variation of these BCs to assess their effect on slope behaviour. Specifically, daily and monthly atmospheric data were contrasted, dynamic vegetation growth was juxtaposed with static vegetation, and water extraction with depth due to transpiration was compared with a simplified approach where evapotranspiration was modelled to occur from the ground surface. A representative cut slope was considered, and fully coupled hydro-mechanical analyses were conducted under different BCs to study its stability and serviceability. The numerical results highlight which modelling choices significantly influence predicted performance, particularly under climate change, and which can be safely simplified. Guidance is provided for balancing computational efficiency with accuracy in geotechnical design.
Sadatieh et al. (2026) studied this question.