## Gravity-driven groundwater flow and slope failure potential. 1. Elastic effective-stress model

Hilly or mountainous topography influences gravity-driven groundwater flow and the consequent distribution of effective stress in shallow subsurface environments. Effective stress, in turn, influences the potential for slope failure. To evaluate these influences, the authors formulate a two-dimensional, steady state, poroelastic model. The governing equations incorporate groundwater effects as body forces, and they demonstrate that spatially uniform pore pressure changes do not influence effective stresses. They implement the model using two finite element codes. As an illustrative case, they calculate the groundwater flow field, total body force field, and effective stress field in a straight, homogeneous hillslope. The total bodymore »