Following the Flow: How water movement impacts ecosystems and contaminants in a riparian wetland
By Tyjaha Steele and Katrina Ford
Researchers at the University of Georgia’s Savannah River Ecology Laboratory studied water movement in wetlands and its role in filtering contaminants in the Tims Branch watershed, a riparian wetland on the Savannah River Site in Aiken, South Carolina.
“We chose this area specifically to understand how water moves. This allows us to predict how wetlands hold onto contaminants,” explains Daniel Kaplan, a senior research scientist at SREL, associate director of the University of Georgia’s Research Institute, and lead investigator of this study.
The research team collected monthly water samples from rainfall, streams, and groundwater at different sites within the watershed. By analyzing stable isotopes of hydrogen (δ²H) and oxygen (δ¹⁸O), they traced how different water sources mixed over time. Additional measurements were collected and helped determine how groundwater chemistry influenced stream water quality.
The study found that groundwater renewed at 2–4% per day, taking about two to four weeks to mix fully. Groundwater contributed up to 4% of stream water in some areas, while stream water comprised nearly 70% of groundwater in others.
These exchanges shifted seasonally, with groundwater flowing into streams more in winter and stream water seeping into the soil in summer, influencing water quality and contaminate movement.
The movement of water within the environment is a key factor in assessing the distribution of various heavy metals and contaminants, including uranium, throughout a riparian wetland. Effective environmental management is crucial to ensuring the health and safety of the Central Savannah River Area.
“For future work, we hope to utilize this hydrological model with other studies to improve contaminant management and reduce risks to both human and environmental health across the CSRA and DOE Complex,” states Kaplan.
The original study titled, “Hydrological controls of a riparian wetland based on stable isotope data and model simulations,” was published in the journal Isotopes in Environmental and Health Studies (IEHS) and was written by Peter H. Santschi, Chen Xu, Peng Lin, Chris M. Yeager, Pieter Hazenberg, and Daniel I. Kaplan. This work was completed in collaboration with researchers from Texas A&M University, Florida International University, and the Argonne National Laboratory, and the University of Georgia’s Savannah River Ecology Laboratory.