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Detecting drawdowns masked by environmental stresses with water-level models

Ground Water

By:
, ,
DOI: 10.1111/gwat.12042

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Abstract

Detecting and quantifying small drawdown at observation wells distant from the pumping well greatly expands the characterized aquifer volume. However, this detection is often obscured by water level fluctuations such as barometric and tidal effects. A reliable analytical approach for distinguishing drawdown from nonpumping water-level fluctuations is presented and tested here. Drawdown is distinguished by analytically simulating all pumping and nonpumping water-level stresses simultaneously during the period of record. Pumping signals are generated with Theis models, where the pumping schedule is translated into water-level change with the Theis solution. This approach closely matched drawdowns simulated with a complex three-dimensional, hypothetical model and reasonably estimated drawdowns from an aquifer test conducted in a complex hydrogeologic system. Pumping-induced changes generated with a numerical model and analytical Theis model agreed (RMS as low as 0.007 m) in cases where pumping signals traveled more than 1 km across confining units and fault structures. Maximum drawdowns of about 0.05 m were analytically estimated from field investigations where environmental fluctuations approached 0.2 m during the analysis period.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Detecting drawdowns masked by environmental stresses with water-level models
Series title:
Ground Water
DOI:
10.1111/gwat.12042
Volume
51
Issue:
3
Year Published:
2013
Language:
English
Publisher:
Wiley
Contributing office(s):
Nevada Water Science Center
Description:
11 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
322
Last page:
332