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Stochastic Analysis of Unsaturated Flow in Heterogeneous Soils: 3. Observations and Applications
Author(s) -
Yeh T.C. Jim,
Gelhar Lynn W.,
Gutjahr Allan L.
Publication year - 1985
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr021i004p00465
Subject(s) - hydraulic conductivity , anisotropy , water content , soil water , capillary pressure , soil science , capillary action , groundwater recharge , surface runoff , vadose zone , moisture , geology , environmental science , geotechnical engineering , materials science , groundwater , porous medium , porosity , aquifer , physics , composite material , optics , biology , ecology
Results of stochastic theory for flow in heterogeneous soils are analyzed by comparisons with laboratory experiments and field observations, and through applications examples. The two key theoretical results are (1) the variability of capillary pressure or moisture content increases when mean capillary pressure increases and (2) the anisotropy ratio (horizontal/vertical) of effective (mean) unsaturated hydraulic conductivity increases when mean capillary pressure increases or mean moisture content decreases. Comparisons with the field data on moisture content and capillary pressure variability show trends similar to those predicted by the theory. Calculations of hydraulic conductivity anisotropy based on two actual soils show that the variations in soil texture produce large changes in anisotropy as the mean capillary pressure changes. Several previously reported field observations and laboratory experiments support the theoretical finding of a capillary pressure dependent hydraulic anisotropy for unsaturated flow. The importance of this anisotropy effect in applications involving groundwater recharge, irrigation, surface runoff generation, and waste isolation is discussed.