December 20, 2018
Groundwater-River Water Exchange Alters Semi-Arid Ecosystem Dynamics
Study demonstrates how carbon uptake and surface energy fluxes are influenced by lateral groundwater-river water exchange.
The Science
Lateral groundwater-river water exchange could play an important role in determining how ecosystem fluxes will respond to changing hydroclimatic conditions in semiarid regions. However, few studies have collected eddy covariance measurements to quantify the impacts of groundwater-surface water interactions on ecosystem fluxes. Researchers collected a unique dataset demonstrating the critical impact of groundwater-surface water exchange on riparian ecosystem fluxes.
The Impact
This work demonstrates that groundwater-river water exchange could dramatically alter ecosystem carbon uptake and evapotranspiration. Also, to predict the response of terrestrial ecosystems to future Earth system changes, the role of lateral water flow in the groundwater-river continuum must be considered, along with the roles of precipitation and other meteorological variables.
Summary
This research used one year of data collected at two newly established eddy covariance sites (AmeriFlux sites US-Hn1 and US-Hn2) to examine the impact of groundwater-surface water exchange on riparian ecosystem fluxes. In an upland ecosystem without groundwater access, during the dry season carbon uptake was strongly constrained due to the lack of available moisture. In contrast, in a riparian ecosystem, lateral groundwater-river water exchange provided an additional water source, which allowed the ecosystem to maintain high carbon uptake during the dry season.
Principal Investigator
Heping Liu
Washington State University
[email protected]
Program Manager
Paul Bayer
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
[email protected]
Funding
This work was supported by the U.S. Department of Energy (DOE) Office of Biological and Environmental Research (BER) as part of BER’s Subsurface Biogeochemical Research program (now the Environmental System Science program) at Pacific Northwest National Laboratory.
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References
Missik, J.E.C., et al. "Groundwater‐River Water Exchange Enhances Growing Season Evapotranspiration and Carbon Uptake in a Semiarid Riparian Ecosystem." Journal of Geophysical Research: Biogeosciences 124 (1), 99–114 (2019). https://doi.org/10.1029/2018JG004666.