method for computing infiltration and redistribution in a discretized moisture content domain

• Published in: Water resources research Vol. 44; no. 8
• Main Authors: Talbot, Cary A, Ogden, Fred L
• Format: Journal Article
• Language: English
• Published: 01.08.2008
• Subjects: coastal plain soils; drainage; equations; estimation; hydrologic models; infiltration (hydrology); loamy sand soils; mathematical models; provenance; soil water content; water table; wetting front; Southeastern United States
• ISSN: 0043-1397; 1944-7973
• DOI: 10.1029/2008WR006815

A new one-dimensional infiltration and redistribution method is proposed as an alternative to the Richards equation (RE) for coupled surface and subsurface models. The proposed method discretizes soil water content into hypothetical hydraulically interacting bins. The entry and propagation of displacement fronts in each bin are simulated by means of explicit infiltration and drainage approximations based on capillary and gravitational driving forces. Wetting front advances within bins create water deficits that are satisfied by capillary-driven interbin flow. The method inherently provides numerical stability by precluding the need to directly estimate nonlinear gradients through numerical schemes. Comparisons of the performance of this method against RE solutions for theoretical, laboratory, and field data in both well-drained and high water table conditions are presented. The new method produces infiltration flux estimates with errors less than 10% compared to a widely used RE solution in tests on multiple soil textures with and without high water table conditions while providing unconditionally guaranteed conservation of mass.