Flow to a well in a five-layer system with application to the Oxnard Basin

Yanhua Li, Shlomo P Neuman

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Nearly 40 years ago, Neuman (1968) developed an analytical solution for drawdown in a system of three aquifers separated by two aquitards when one of the aquifers is pumped at a constant rate. Whereas the simpler case of two aquifers separated by one aquitard has been presented by Neuman and Witherspoon (1969a), the full five-layer solution has not been previously evaluated. We do so here using numerical inversion of its Laplace-transformed version and present selected results graphically in dimensionless form. The solution demonstrates that the effect of pumping propagates across all five layers, adding emphasis to a question previously raised by Neuman and Witherspoon about the validity of leaky aquifer theories that disregard drawdowns in unpumped aquifers. A large-scale, long-term pumping test spanning three aquifers separated by two aquitards near Oxnard, California, has been conducted and analyzed by Neuman and Witherspoon (1972). They evaluated the vertical hydraulic diffusivities of the aquitards using the Neuman-Witherspoon ratio method and their specific storage values on the basis of laboratory consolidation tests. We reinterpret the Oxnard pumping test by coupling the five-layer analytical solution of Neuman (1968) with the parameter estimation code PEST (Doherty 2002) and validate our results against drawdowns from a subsequent pumping test at the site. Our parameter estimates compare favorably with those of Neuman and Witherspoon (1972).

Original languageEnglish (US)
Pages (from-to)672-682
Number of pages11
JournalGround Water
Volume45
Issue number6
DOIs
StatePublished - Nov 2007

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Aquifers
aquitard
aquifer
pumping
drawdown
basin
Consolidation
Parameter estimation
diffusivity
consolidation
Hydraulics
hydraulics
test

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)
  • Water Science and Technology

Cite this

Flow to a well in a five-layer system with application to the Oxnard Basin. / Li, Yanhua; Neuman, Shlomo P.

In: Ground Water, Vol. 45, No. 6, 11.2007, p. 672-682.

Research output: Contribution to journalArticle

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