Invariant solutions of Richards' equation for water movement in dissimilar soils

M. Sadeghi, B. Ghahraman, A. N. Ziaei, K. Davary, K. Reichardt

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Scaling methods allow a single solution to Richards' equation (RE) to suffice for numerous specifc cases of water flow in unsaturated soils. During the past half-century, many such methods were developed for similar soils. In this paper, a new method is proposed for scaling RE for a wide range of dissimilar soils. Exponential-power (EP) functions are used to reduce the dependence of the scaled RE on the soil hydraulic properties. To evaluate the proposed method, the scaled RE was solved numerically considering two test cases: infiltration into relatively dry soils having initially uniform water content distributions, and gravity-dominant drainage occurring from initially wet soil profiles. Although the results for four texturally different soils ranging from sand to heavy clay (adopted from the UNSODA database) showed that the scaled solution were invariant for a wide range of flow conditions, slight deviations were observed when the soil profile was initially wet in the inf ltration case or deeply wet in the drainage case. The invariance of the scaled RE makes it possible to generalize a single solution of RE to many dissimilar soils and conditions. Such a procedure reduces the numerical calculations and provides additional opportunities for solving the highly nonlinear RE for unsaturated water flow in soils.

Original languageEnglish (US)
Pages (from-to)1-9
Number of pages9
JournalSoil Science Society of America Journal
Issue number1
StatePublished - Jan 2012
Externally publishedYes


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