Increasing Water Management Capability at Great Dismal Swamp National Wildlife Refuge to Enhance Resilience
Managers at the Great Dismal Swamp National Wildlife Refuge initiated a project to replace water management structures to restore hydrological function, increase water storage of drained forested peatlands, and sustain groundwater levels. The major climate impacts addressed by the project were increased incidence of severe wildfires (resulting from drought and past land-use practices), increased flooding from heavy rain events, and increased frequency and intensity of drought. Refuge managers have noted successful restoration of historic forest composition and an increased consideration of holistic water management for multiple benefits, including ecosystem health and flood and fire protection.
The Great Dismal Swamp National Wildlife Refuge encompasses more than 112,000 acres of biologically and culturally significant habitats (e.g., Important Bird Area designated sites, National Park Service Natural Landmarks, and Underground Railroad Network to Freedom site) in southeastern Virginia and northeastern North Carolina. The U.S. Fish and Wildlife Service (USFWS) was directed to manage, preserve, and protect the Refuge by the Dismal Swamp Act of 1974. The Refuge is home to forested wetland habitats with peat soils that capture and store carbon. Climate change-driven reductions in precipitation (including a 2004–2011 drought) along with large wildfires in 2008 and 2011 and historic land-use development (e.g., draining, logging) have caused the drying of soils, which in turn increases the risk of catastrophic wildfires that can destroy habitat and emit carbon. The 2008 and 2011 fires emitted approximately 6.2 million metric tons of CO2; rewetting the peat soil reduces fuel loads available for wildfires and limits the risk of additional carbon loss. Refuge staff wanted to prevent further damage from highly-destructive events, address climate change impacts (e.g., increased incidence of wildfire, flooding, and drought), and restore the site’s hydrological function. In 2012, a restoration and water management project was initiated to prevent wildfires, slow water drainage, rewet peat soils, and reduce flooding risks within the Refuge.
This peatland restoration project was conducted between 2012 to 2016 and focused on 20,000–25,000 acres in the northeast corner of the Refuge. The project used an adaptive management approach to replace 14 water management structures to increase the water storage potential of drained forested peatlands, making them more resilient to impacts such as fires and flooding. The core strategy focused on replacing existing water management structures, rather than having to get permitting and public approval on new water management structures. The priority was replacing water management structures installed on-site by the timber industry in the 1940s and 1950s before the Refuge designation. In determining implementation options, managers used U.S. Geological Survey datasets, internal hydrology and forest research, consultants, and a structured decision-making process to strike the right balance in meeting water management, fire and flooding protection, and habitat restoration goals. Refuge staff aimed to achieve multiple wildlife and human community benefits, including increased water storage, reduced vulnerability of peat soils to drought events, enhanced conditions for peat accumulation and carbon sequestration, improved wildlife habitat diversity, improved water quality, community protection from flooding and wildfire risks, and reduced wildfire smoke impacts on public health in surrounding areas.
The project cost $3,130,000 and was funded through the USFWS Hurricane Sandy Resilience Program. Project partners included Christopher Newport University, City of Chesapeake, City of Suffolk, North Carolina Department of Environment and Natural Resources, The Nature Conservancy, U.S. Army Corps of Engineers, U.S. Geological Survey, and Virginia Department of Game and Inland Fisheries.
Outcomes and Conclusions
The project was completed in four years and produced a number of products (e.g., a final report, a hydrological model of the Refuge, and wetland permitting monitoring data). Noted outcomes include a reduction in pollution and restoration of historic forest composition. According to managers of the Refuge, the project led to a greater consideration of managing water for the greater good of the ecosystem, including forest diversity, long-term resilience, and flood and fire protection. Over the long term, success will be indicated when data show that the Refuge has been able to keep groundwater levels higher for longer periods of time to successfully rewet habitats. An additional success would be notable species composition changes (e.g., tree community types) in the Refuge. The Refuge is currently monitoring physical and ecological parameters within the project area, including surface and groundwater elevations and forestry plot data (e.g., species composition, percent canopy cover, regeneration, and growth). The next steps for the Refuge include the implementation of a Habitat Management Plan, which will help to guide management decisions and monitoring efforts.
Sims, S.A., Braddock, K.N., Gregg R.M. (2021). Increasing Water Management Capability at Great Dismal Swamp National Wildlife Refuge to Enhance Resilience. [Case study on a project of the Great Dismal Swamp National Wildlife Refuge]. Product of EcoAdapt’s State of Adaptation Program. Retrieved from CAKE: https://www.cakex.org/case-studies/increasing-water-management-capability-great-dismal-swamp-national-wildlife-refuge-enhance-resilience (Last updated October 2021)