Detecting drawdowns masked by environmental stresses with water-level models.
Bottom Line: 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.
Affiliation: US Geological Survey, 2730 N Deer Run Rd, Carson City, NV 89701, USA.Show MeSH
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Mentions: The reliability of differentiating environmental fluctuations and pumping responses with the drawdown estimation approach was tested with a numerically simulated hypothetical aquifer test, for which drawdowns were known because they were simulated. This hypothetical system was designed with some degree of hydrogeologic complexity. The hydrogeologic framework was conceptualized as layered sequences of hydrostratigraphic units that were offset vertically more than 500 m across a major fault (Figure 3). The fault was simulated as an interface where hydrostratigraphic units were juxtaposed; the fault was not assigned unique hydraulic properties. This hypothetical sequence is similar to the vertical distribution of units that were mapped in cross sections beneath Pahute Mesa (National Security Technologies, LLC 2010).
Affiliation: US Geological Survey, 2730 N Deer Run Rd, Carson City, NV 89701, USA.