Journal of Hydraulic Structures

Journal of Hydraulic Structures

Well Hydraulics in a Two-Zone Aquifer under Ambient Flow: Analytical Study

Articles in Press

Document Type : Research Paper

Authors
Ali Mahdavi 1
Ying-Fan Lin 2
1 Department of Civil Engineering, Arak University, Iran
2 Department of Civil Engineering, Chung Yuan Christian University, Taoyuan, Taiwan
10.22055/jhs.2026.52699.1391
Abstract
Pump-and-treat performance depends on capture zones around pumping wells. In low-permeability aquifers, constant-rate models often misrepresent flow. This study develops a mathematical model for groundwater flow under constant-head pumping to delineate the well capture zone. The model includes wellbore skin and the regional hydraulic gradient. Closed-form expressions for drawdown and stream function support flow-net analysis in the skin and formation zones. Adaptive finite-element simulations validate the solutions. Results identify a downstream stagnation point, define capture-zone envelopes, and quantify transit time as functions of ambient-flow strength and aquifer contrasts. Wellbore flow increases only when skin permeability exceeds formation permeability; when formation conductivity exceeds skin conductivity, skin-radius effects become negligible. Dimensionless transit time decreases from ~90,000 to ~30,000 as ambient-flow strength increases from 0.01 to 0.03, indicating regional gradients accelerate transport, while heterogeneity exerts a weaker influence. A least-squares parameter-estimation procedure recovers hydraulic conductivity and ambient-flow velocity. The framework supports design and evaluation of constant-head pump-and-treat systems in low-permeability aquifers.
Keywords
Analytical groundwater modeling
Aquifer heterogeneity
Capture zone delineation
constant-head pumping
Two-zone groundwater flow
Subjects
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Journal of Hydraulic Structures

Articles in Press, Accepted Manuscript
Available Online from 12 November 2026