Traditional analysis of aquifer tests uses the observed hydrograph at one well caused
by pumping at another well for estimating transmissivity and storage coefficient of an
aquifer. The analysis relies on Theis' or Jacob's approximate solution, which assumes
aquifer homogeneity. Aquifers are inherently heterogeneous at different scales. If the
observation well taps into a low permeability zone while the pumping well is located in a
high permeable zone, the resulting situation contradicts the homogeneity assumption
embedded in the traditional analysis. As a result, a practical but important question we
ask: What do we derive from the traditional analysis?
Using numerical experiments in synthetic aquifers, we answer this question.
Results of the experiments indicate that the effective transmissivity, Teff , and storage
coefficient, Seff , values vary with time, as well as the principal directions of the
transmissivity, but both values approach their geometric means of the aquifer at large
times. Analysis of the estimated transmissivity (T) and storage coefficient (S ) using well
hydrographs from a single observation well shows that at early times, both the estimated
T and S values vary with time. At late times, both estimates approach local averages
near the observation well. The T value approaches but does not equal Teff , representing
an average value over a broad area in the vicinity of the observation well while the S value converges to the value dominated by the storage coefficient near the
observation wells (i.e., its average area is much smaller than that of the t value).
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/615770 |
| Date | 10 1900 |
| Creators | Wu, Cheng-Mau, Yeh, Tian-Chyi J., Lee, Tim Hau, Hsu, Nein-Sheng, Chen, Chu-Hui, Sancho, Albert Folch |
| Contributors | Department of Hydrology & Water Resources, The University of Arizona |
| Publisher | Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ) |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Technical Report |
| Source | Provided by the Department of Hydrology and Water Resources. |
| Rights | Copyright © Arizona Board of Regents |
| Relation | Technical Reports on Hydrology and Water Resources, No. 04-03 |
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