Evaluation of the streambed leakage concept in analytical models using data from three pumping tests

Authors

Sefan J. Kollet, Lawrence Livermore National LaboratoryFollow
Vitaly A. Zlotnik, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

2007

Comments

Published by Kollet & Zlotnik in Hydrogeology Journal (2007) 15

Abstract

Two-dimensional analytical models of pumping induced drawdown and stream depletion account for the streambed properties and stream geometry. Using data from three pumping tests performed under various hydrologic conditions, the following hypotheses were tested: (1) a partially penetrating stream at a certain distance from the pumping well can be represented by the streambed leakage term in the analytical models; (2) in the streambed leakage term, the streambed conductance coefficient λ=(WK′)/m′ accounts for the average stream width W, the streambed thickness m′, and hydraulic conductivity K′. The first hypothesis was tested by comparing results from tests under flow and no-flow stream conditions. The second hypothesis was tested by comparing results from two tests under low and high streamflow conditions. Similar estimates of the hydraulic conductivity and storativity for all tests indicate the validity of the streambed leakage term. The drawdown data of the test under low- and high-flow conditions (varying W) do not follow the predictions of the analytical models, which results in inconsistent λ estimates. Thus, for different hydrologic conditions, λ cannot be scaled solely by the stream width W. One possible explanation for this result is streambed dynamics caused by the changes in the stream stage.