Direct solution of unsaturated flow in randomly heterogeneous soils

Z. Lu, S. P. Neuman, A. Guadagnini, D. M. Tartakovsky

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Scopus citations


We consider steady state unsaturated flow in bounded randomly heterogeneous soils under the influence of random forcing terms. Our aim is to predict pressure heads and fluxes without resorting to Monte Carlo simulation, upscaling or linearization of the constitutive relationship between unsaturated hydraulic conductivity and pressure head. We represent this relationship through Gardner's exponential model, treating its exponent α as a random constant and saturated hydraulic conductivity, K(s), as a spatially correlated random field. This allows us to linearize the steady state unsaturated flow equations by means of the Kirchhoff transformation, integrate them in probability space, and obtain exact integro-differential equations for the conditional mean and variance-covariance of transformed pressure head and flux. We solve the latter for flow in the vertical plane, with a point source, by finite elements to second-order of approximation. Our solution compares favorably with conditional Monte Carlo simulations, even for soils that are strongly heterogeneous.

Original languageEnglish (US)
Title of host publicationComputational methods in water resources - Volume 2 - Computational methods,surface water systems and hydrology
EditorsL.R. Bentley, J.F. Sykes, C.A. Brebbia, W.G. Gray, G.F. Pinder, L.R. Bentley, J.F. Sykes, C.A. Brebbia, W.G. Gray, G.F. Pinder
Number of pages8
ISBN (Print)9058091252
StatePublished - 2000
EventComputational Methods in Water Resources - Calgary, Canada
Duration: Jun 25 2000Jun 29 2000


OtherComputational Methods in Water Resources

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)
  • Engineering(all)
  • Environmental Science(all)


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