Environmental Significance of the Groundwater-Surface Water Interaction Zone
The subsurface interaction zone is a critical environmental interface where groundwater and surface water meet. It is a diffuse and extended zone that exists beneath and along the inland margins of most streams and rivers. Owing to seasonal changes in surface water volumes driven by precipitation, the zone experiences water flows that are dynamic in direction and magnitude, with significant surface water recirculation. Microorganisms flourish from the mixing of nutrients present in both surface water and groundwater.
The subsurface interaction zone influences the ecosystem health and quality of surface waters, and displays feedbacks to climate. Unwanted solutes of anthropogenic origin in groundwater (contaminants, nutrients) can be transformed to less harmful forms in this zone, while biogenic processes may generate greenhouse gases of climate concern. Understanding the function of this zone and developing robust models that predict its control on environmental chemical fluxes to surface water is crucial for sustainable energy, agriculture and legacy waste management.
Key science gaps being addressed by research are:
- Factors controlling the dynamics, extent and function of the subsurface interaction zone under non-stationary climate
- Role of subsurface interaction zone processes in modulating the flux of contaminants, nutrients, and biogenic gases between groundwater and surface water
- Robust models that integrate microbiology, hydrology and geochemistry for local- and regional-scale predictions.
Our vision is to bridge spatial and temporal scales at which fundamental processes and their coupling are best quantified by observation and experiment in the laboratory and field, with those at which applied model predictions are required (often at the watershed scale) using a multiscale analysis and modeling framework.
Research Activities
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Reach-scale Behavior
We will assess effects of daily, seasonal, and yearly variations in the hydrologic cycle and climate on groundwater-surface water interactions....
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Local-scale Behavior
We will monitor microbial community structure, biogeochemical processes, and hydrology across the groundwater-surface water mixing zone...
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Fine-scale Processes
We will develop fundamental understanding of coupled hydrologic and biogeochemical processes that control the reactive transport of contaminants...
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Multiscale Science and Modeling
We will apply novel multiscale modeling that integrates bottom-up model development and optimal hybrid multiscale model deployment...
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Data Assimilation
We will establish and maintain a central repository for processing, Quality Assurance and Control, storage, and dissemination...
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Contacts
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DOE Program Managers
Paul Bayer
David Lesmes -
BER-CESD Sector Manager
Charlette Geffen
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Principal Investigators
John Zachara
Jim Fredrickson
Tim Scheibe
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Project Coordinator
Sonia Enloe -
Content Manager
Sarah Shoemaker
Acknowledgements
This research is supported by the U.S. Department of Energy (DOE), Office of Biological and Environmental Research (BER), as part of BER's Subsurface Biogeochemistry Research Program (SBR). This contribution originates from the SBR Scientific Focus Area (SFA) at the Pacific Northwest National Laboratory (PNNL).
A portion of the research is performed within the Environmental Molecular Sciences Laboratory (EMSL), a DOE Office of Science User Facility sponsored by BER and located at PNNL.