Semi-Analytical Modeling of Transient Stream Drawdown and Depletion in Response to Aquifer Pumping

TL;DR

This paper introduces semi-analytical models that incorporate transient stream stage changes in response to groundwater pumping, improving predictions of stream depletion over traditional fixed-stage models.

Contribution

The paper develops new semi-analytical models accounting for transient stream stage drawdown, addressing a key limitation of existing fixed-stage models.

Findings

Models reduce to fixed-stage models with large stream storage.

Field data confirms stream stage drawdown occurs due to pumping.

Application estimates aquifer parameters and streambed conductance.

Abstract

Analytical and semi-analytical models for stream depletion with transient stream stage drawdown induced by groundwater pumping are developed to address a deficiency in existing models, namely, the use of a fixed stream stage condition at the stream-aquifer interface. Field data are presented to demonstrate that stream stage drawdown does indeed occur in response to groundwater pumping near aquifer connected streams. A model that predicts stream depletion with transient stream drawdown is developed, based on stream channel mass conservation and finite stream channel storage. The resulting models are shown to reduce to existing fixed-stage models in the limit as stream channel storage becomes infinitely large, and to the confined aquifer flow with a no-flow boundary at the streambed in the limit as stream storage becomes vanishingly small. The model is applied to field measurements of aquifer and stream drawdown, giving estimates of aquifer hydraulic parameters, streambed conductance and a measure of stream channel storage. The results of the modeling and data analysis presented herein have implications for sustainable groundwater management.