  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.
