Evolution of the radius of investigation during recovery tests

Etienne Bresciani, Raghwendra N. Shandilya, Peter K. Kang, Seunghak Lee

Research output: Contribution to journalArticlepeer-review

Abstract

Pumping tests are routinely performed to characterize aquifers. In particular, recovery tests involve analyzing the residual drawdown after the termination of pumping. Evaluating the radius of investigation of pumping tests is important for test design and interpretation. However, the radius of investigation during the recovery phase has rarely been discussed in the literature. Here, we derive exact (semi-analytical) and approximate (fully analytical) solutions for the radius of investigation during the recovery phase, and present a sensitivity analysis for typical parameter values. During recovery, the radius of investigation shows non-monotonic behavior: it first increases, then decreases, and eventually vanishes. The maximum radius can be up to five times larger than that at the end of the pumping phase in the investigated range of parameter values. However, the conditions yielding a large radius of investigation are such that the time at which the maximum occurs is relatively large: up to one hundred times the pumping duration, depending on the parameters. Thus, in practice, one may need to find a compromise between the size of the investigated area and the time required for the test. In addition to the aquifer parameters, we observe that the pumping rate and duration, and the apparent measurement resolution are key parameters controlling the radius of investigation during recovery. Finally, the approach is applied to a field example. This study provides fundamental insight on the radius of investigation of recovery tests as well as practical solutions, thereby facilitating the design and interpretation of recovery tests in practice.

Original languageEnglish (US)
Article number125346
JournalJournal of Hydrology
Volume590
DOIs
StatePublished - Nov 2020

Bibliographical note

Funding Information:
We are indebted to Thomas Klinka (BRGM, France) for his support in finding the field example and related information. The authors acknowledge support from the Korea Research Fellowship program funded by the Ministry of Science and ICT through the National Research Foundation of Korea (grant 2016H1D3A1908042), the Future Research Program (2E30510) funded by the Korea Institute of Science and Technology (KIST), and the Korea Environmental Industry & Technology Institute (KEITI) through the Subsurface Environment Management (SEM) Project (2018002440006) funded by the Korea Ministry of Environment (MOE). PKK also acknowledges the College of Science & Engineering at the University of Minnesota and the George and Orpha Gibson Endowment for its generous support of Hydrogeology, and the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR). Alraune Zech and two anonymous reviewers are gratefully acknowledged for their comments, which helped improve the manuscript.

Funding Information:
We are indebted to Thomas Klinka (BRGM, France) for his support in finding the field example and related information. The authors acknowledge support from the Korea Research Fellowship program funded by the Ministry of Science and ICT through the National Research Foundation of Korea (grant 2016H1D3A1908042 ), the Future Research Program (2E30510) funded by the Korea Institute of Science and Technology (KIST), and the Korea Environmental Industry & Technology Institute (KEITI) through the Subsurface Environment Management (SEM) Project (2018002440006) funded by the Korea Ministry of Environment (MOE). PKK also acknowledges the College of Science & Engineering at the University of Minnesota and the George and Orpha Gibson Endowment for its generous support of Hydrogeology, and the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR). Alraune Zech and two anonymous reviewers are gratefully acknowledged for their comments, which helped improve the manuscript.

Publisher Copyright:
© 2020 Elsevier B.V.

Keywords

  • Aquifer test
  • Buildup test
  • Pumping test
  • Radius of investigation
  • Recovery test
  • Well test

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