In this paper, we present a class of solvers developed for the parallel solution of Richards' equation, a model used in variably saturated ow simulations. These solvers take advantage of the fast, robust convergence of globalized Newton methods as well as the parallel scalability of multigrid preconditioners. We compare two multigrid methods. The methods di er primarily in their handling of dis...

Numerical solutions to the equation governing variably saturated flow are usually obtained using either the finite difference (FD) method or the finite element (FE) method. A detailed comparison of these methods shows that the main difference between them is in how the numerical schemes spatially average the variation of material properties. Further differences are also observed in the way that...

A least-squares mixed nite element formulation is applied to the nonlinear elliptic problems arising in each time-step of an implicit Euler discretization for variably saturated ow problems. This approach simultaneously constructs approximations to the ux in Raviart-Thomas spaces and to the hydraulic potential by standard H 1-conforming linear nite elements. Two important properties of the leas...

1. INTRODUCTION This paper presents a finite-element collocation scheme for simulating variably saturated flows in two space dimensions. The scheme is an extension of a mass conserving one-dimensional formulation presented earlier [Allen and Murphy, 1985). The present exposition gives a complete description of work reported more briefly in the work by Murphy and Allen [1986]. Among the key feat...

ABSTRACT-Application of models for simulation of solute and pollutants transport in soil can reduce time and costs for remediation process. HYDRUS-1D model was developed to simulate the one–dimensional flow of soil water, heat, solute and viruses in variably saturated–unsaturated porous media. The objective of this investigation is to determine the solute transport parameters in disturbed soil ...

important factors in controlling subsurface flow and/or contaminant transport, and/or evaluating regional and Constructed wetlands (CWs) are becoming increasingly popular global water cycles (Scanlon et al., 2002). worldwide for removing organic matter (OM), nutrients, trace elements, pathogens, or other pollutants from wastewater and/or runoff Many or most vadose zone models consider the trans...

Soil-gas diffusivity and its variation with soil moisture plays a fundamental role in diffusion-controlled migration of climate-impact gases from different terrestrial agroecosystems including cultivated soils managed pasture systems. The wide contrast texture structure (e.g., density, aggregation) agriculture topsoils (0–10 cm) makes it challenging for soil-gas predictive models to make accura...