Pumping-induced drawdown and stream depletion in a leaky aquifer system

Area of Science:

• Hydrogeology
• Environmental Engineering
• Water Resources Management

Background:

• Groundwater pumping impacts streamflow, typically modeled using interconnected stream-aquifer systems.
• Existing models often assume an impermeable layer beneath the pumped aquifer, which may not reflect reality.

Purpose of the Study:

• Develop a semianalytic solution for drawdown and stream depletion that accounts for aquitard leakage.
• Investigate the role of aquitard leakage as a recharge mechanism in stream-aquifer systems.

Main Methods:

• Developed a new semianalytic solution for analyzing stream-aquifer interactions under pumping conditions.
• The solution does not require the assumption of an impermeable formation underlying the aquifer.

Main Results:

• Pumping-induced leakage through an underlying aquitard can be a significant recharge source.
• The importance of leakage increases with the distance between the pumping well and the stream.
• Ignoring aquitard leakage can lead to overestimations of drawdown and stream depletion.

Conclusions:

• Aquitard leakage is a crucial factor in stream-aquifer system assessments, even with low-transmissivity aquitards.
• Accurate estimation of aquitard properties is vital for effective water resources management and water rights adjudication.
• The new solution offers a versatile tool for practical assessments of pumping-induced stream-aquifer interactions, provided site-specific data support leakage.