2
Identifying Soil and Transport Properties Using a
Model of Infiltration-Redistribution Flow and
Transport in the Unsaturated Zone
s.c. Lessoff 1, P. Indelman 2
J Dept. of Fluid Mechanics and Heat Transfer, University of Tel Aviv, Ramat
Aviv 69978, Israel. e-mail: slessofJ@eng.tau.ac.il Tel.: +972- 3-640-8930.
Fax: +972- 3-640-7334
2 Faculty of Civil Engineering, Environmental and Water Resources Engineering,
Technion, Haifa 32000, Israel, e-mail: Indelman@techunix.technion.ac.il
Tel.: +972-4-829-2427. Fax: +972- 4-822-8898
Abstract
Reactive transport properties under unsteady unsaturated flow conditions are
estimated from field-measured transport data. The data is from a recent field
experiment (Dror et al. 1999a,b) in which herbicides (Bromacil, Atrazine, and
Terbuthylazine) applied at the soil surface were transported by a few cycles of
intermittent irrigation, and concentrations were measured to a depth of 1.2 m by
gas chromatography. An analytic stochastic model of flow and reactive transport
accounting for multiple infiltration-redistribution cycles is applied in an inverse
mode to identify soil and chemical transport properties and measurement
uncertainty. Transport, measured at the end of water redistribution, is more
sensitive to residual water in the field and less sensitive to the hydraulic
conductivity and maximum saturated moisture content. Sorption in the field is
found to be less than laboratory-based predictions. The degradation-rate
coefficients agree with laboratory measurements.
1 Introduction
Predicting and controlling the behavior of organic chemicals in the field is a
difficult and complex problem due to the large number of processes that affect
contaminant propagation. In some field tests, organic chemicals leach to
groundwater with unexpected rapidity (Flury 1996), while in others they remain in
the field for exceptionally long periods (Bowmer 1991). A large body of literature
is devoted to improving our understanding of chemical behavior at field scale and
to relating field behavior to quantifiable transport processes.
H. Rubin / P. Nachtnebel / J. Fuerst / U. Shamir
Preserving the Quality of Our Water Resources
© Springer-Verlag Berlin Heidelberg 2002
Identifying Soil and Transport Properties Using a
Model of Infiltration-Redistribution Flow and
Transport in the Unsaturated Zone
s.c. Lessoff 1, P. Indelman 2
J Dept. of Fluid Mechanics and Heat Transfer, University of Tel Aviv, Ramat
Aviv 69978, Israel. e-mail: slessofJ@eng.tau.ac.il Tel.: +972- 3-640-8930.
Fax: +972- 3-640-7334
2 Faculty of Civil Engineering, Environmental and Water Resources Engineering,
Technion, Haifa 32000, Israel, e-mail: Indelman@techunix.technion.ac.il
Tel.: +972-4-829-2427. Fax: +972- 4-822-8898
Abstract
Reactive transport properties under unsteady unsaturated flow conditions are
estimated from field-measured transport data. The data is from a recent field
experiment (Dror et al. 1999a,b) in which herbicides (Bromacil, Atrazine, and
Terbuthylazine) applied at the soil surface were transported by a few cycles of
intermittent irrigation, and concentrations were measured to a depth of 1.2 m by
gas chromatography. An analytic stochastic model of flow and reactive transport
accounting for multiple infiltration-redistribution cycles is applied in an inverse
mode to identify soil and chemical transport properties and measurement
uncertainty. Transport, measured at the end of water redistribution, is more
sensitive to residual water in the field and less sensitive to the hydraulic
conductivity and maximum saturated moisture content. Sorption in the field is
found to be less than laboratory-based predictions. The degradation-rate
coefficients agree with laboratory measurements.
1 Introduction
Predicting and controlling the behavior of organic chemicals in the field is a
difficult and complex problem due to the large number of processes that affect
contaminant propagation. In some field tests, organic chemicals leach to
groundwater with unexpected rapidity (Flury 1996), while in others they remain in
the field for exceptionally long periods (Bowmer 1991). A large body of literature
is devoted to improving our understanding of chemical behavior at field scale and
to relating field behavior to quantifiable transport processes.
H. Rubin / P. Nachtnebel / J. Fuerst / U. Shamir
Preserving the Quality of Our Water Resources
© Springer-Verlag Berlin Heidelberg 2002