Discharge, Groundwater Gradients, and Streambed Micro-Topography Control the Temporal Dynamics of Transient Storage...

Area of Science:

• Environmental Science
• Hydrology
• Geomorphology

Background:

• Contradictory interpretations of transient storage modeling (TSM) hinder understanding of stream solute transport.
• Hydrologic conditions significantly influence solute transport, necessitating accurate TSM parameterization.

Purpose of the Study:

• To calibrate and assess the identifiability of TSM parameters under various hydrologic conditions.
• To investigate the influence of in-stream and hyporheic exchange on transient storage in streams.
• To develop a hydrograph illustrating dynamic storage evolution with changing discharge.

Main Methods:

• Conducted 30 instantaneous tracer experiments in the Weierbach stream, Luxembourg.
• Employed an iterative modeling approach to calibrate TSM parameters.
• Utilized near-stream groundwater wells and LIDAR scans to assess hyporheic zone and sediment areas.

Main Results:

• Increasing discharge leads to greater parameter interaction, requiring more data for identifiable TSM parameters.
• At low discharge, transient storage is governed by in-stream and hyporheic exchange.
• At high discharge, in-stream storage zones integrate into the channel, and hyporheic exchange decreases.

Conclusions:

• Transient storage dynamics in streams are complex and discharge-dependent.
• Accurate TSM parameter estimation requires considering both in-stream and hyporheic processes.
• The generated hydrograph provides valuable predictive insights for tracer experiments.