Agricultural effects on air–soil exchange and slope instability

This study aims to understand in what manner a change from grassland to irrigated apple orchards can produce significant changes on the atmospheric soil–water exchange and in turn on the pore water pressure distribution with depth. Both changes may affect slope stability, as a result of infiltration, a rising water table and modified suction profiles. Pore pressure distributions were determined over an average of a 1-year period. The water balance considers infiltration due to precipitation and irrigation, cleared of run-off losses, and evaporation from soil and induced by plant transpiration. Evaporation and infiltration are related to the climate time history at the ground surface and the suction–saturation response of the soil–vegetation system. Vegetation includes lawn, as the reference condition, and apple trees, new or full-production orchards, under sprinkler or drip irrigation. Slope stability was analysed by neglecting the reinforcing effects of the roots, although this is beneficial for shallow slides, and assuming a planar ground surface.