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Modeling one‐dimensional infiltration into very dry soils: 2. Estimation of the soil water parameters and model predictions
Author(s) -
Hills R. G.,
Hudson D. B.,
Porro I.,
Wierenga P. J.
Publication year - 1989
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/wr025i006p01271
Subject(s) - lysimeter , infiltration (hvac) , loam , hydraulic conductivity , soil water , soil science , environmental science , water content , richards equation , hydrology (agriculture) , geology , geotechnical engineering , materials science , composite material
Using a water content based one‐dimensional finite difference algorithm, we model infiltration into a 6‐m‐lysimeter column containing alternating layers of air dried clay loam and sand. We use van Genuchten's equation to model the h−θ relationship and both Campbell's and Mualem's equations to model the K−θ relationship. Several sets of model parameters are estimated using data generated from various combinations of laboratory drainage experiments, laboratory measurements of saturated hydraulic conductivity, lysimeter observations of initial conditions, and lysimeter observations of water redistribution. We find that predictions of infiltration based on field redistribution data give the best agreement with the observed infiltration into the lysimeter. We also find that the use of Campbell's K−θ relationship results in closer agreement between the infiltration model predictions and the lysimeter observations than does the use of Mualem's K−θ equation. The results of this study show that infiltration model predictions for a carefully controlled field scale lysimeter are very sensitive to the field and laboratory techniques used to estimate the soil water parameters.