Journal Published Online: 27 August 2020
Volume 44, Issue 4

Evaluating at Three Scales the Hydraulic Conductivity in an Unconfined and Stratified Alluvial Aquifer



The values of hydraulic conductivity (K) were evaluated at three scales in a stratified alluvial aquifer. The small scale is that of hundreds of soil samples for which K was estimated using predictive methods. A first estimate assumed that each sample was homogeneous. A second estimate proceeded with the modal decomposition for the grain-size distribution curve: this quantified the existing and visually confirmed stratification before predicting K. The medium scale is that of hundreds of variable-head (slug) permeability tests in monitoring wells. The large scale is that of 16 pumping tests in steady-state conditions. The aquifer heterogeneity was quantified with the K values distribution curves for small and medium scales and their modal decompositions. The large data sets provided an excellent opportunity to check the lognormal assumption for the K distributions. Large-scale K values were predicted from the small-scale K distribution with assumed stratification and also from medium-scale K distribution: these predicted values were found to be equal to the mean K value of pumping tests. Therefore, if the grain-size distributions are correctly interpreted and the field permeability tests are correctly performed and interpreted, the distribution curves for the small-scale and medium-scale K values explain the large-scale K values of pumping tests, and there is no need to invoke any scale effect.

Author Information

Chapuis, Robert P.
Department of Civil, Geological, and Mining Engineering, Polytechnique Montréal, Montreal, Quebec, Canada
Pages: 23
Price: $25.00
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Stock #: GTJ20180170
ISSN: 0149-6115
DOI: 10.1520/GTJ20180170