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Transient and Steady‐State Solute Transport Through a Large Unsaturated Soil Column
Author(s) -
Porro I.,
Wierenga P. J.
Publication year - 1993
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.1993.tb01811.x
Subject(s) - tritiated water , steady state (chemistry) , infiltration (hvac) , moisture , water content , transient (computer programming) , transient state , chemistry , water transport , water flow , tracer , hydraulic conductivity , soil science , soil water , environmental science , thermodynamics , geology , geotechnical engineering , tritium , physics , organic chemistry , engineering , computer science , nuclear physics , electrical engineering , operating system
The use of steady‐state models can sometimes reduce the computational resources and input data required for solution of transient transport problems. A large column experiment was performed to test whether solute transport parameters determined from a steady flow experiment may be used in transient, unsaturated flow and transport model predictions. Tritiated water and bromide were applied at a steady rate to the top of a 0.95 m diameter by 6 m deep soil column containing unsaturated soil. After 10 days, tracers were eliminated from the irrigation water. When the soil moisture content within the column ceased to change, another 10‐day pulse of tritiated water and bromide was applied, followed by water without tracers. Transport model parameters were determined through optimization, using breakthrough curves observed at various depths. The tritiated water and bromide pulses lagged behind the wetting front during infiltration into the relatively dry soil. The bromide pulse moved 17–20% faster than the tritiated water pulse, because of anion exclusion. Breakthrough curves for the transient and steady‐state experiments were similar. Because the solute fronts lagged significantly behind the moisture fronts, steady‐state transport parameters, when used in a fully transient numerical model, fairly described the transport under transient conditions.