Numerical simulation of surface barriers for shrub-steppe ecoregions

Abstract

Surface barriers, constructed of earthen materials, are a viable option for long-term management of contaminated sites within arid and semi-arid environments. Design and licensing of surface barriers will require a demonstrated understanding of the multidimensional nonisothermal geohydrologic and coupled ground surface to atmosphere water mass and energy transport processes that control water infiltration to the subsurface. A prototype barrier on a shrug-steppe site at Hanford has been monitored since 1994, providing vegetation and water balance data that includes drainage from the sideslopes. As a prelude to inverse numerical modeling to estimate critical parameters for the prototype barrier, this paper describes and demonstrates a numerical simulator for modeling the prototype barrier in shrub-steppe environments. The numerical simulator comprises a three-dimensional nonisothermal multifluid subsurface flow and transport simulator fully coupled to a modified nonlinear sparsely vegetated (are substrate to closed canopy) evapotranspiration module that mechanistically predicts evaporation.