2020 journal article
Impact of control structures on hydrologic restoration within the Great Dismal Swamp
ECOLOGICAL ENGINEERING, 158.
The Great Dismal Swamp (GDS) is a 45,000-ha state and federally protected Coastal Plain peatland located on the border of North Carolina and Virginia that contains stands of Bald cypress and the globally threatened Atlantic white cedar. Centuries of drainage and logging have substantially altered the hydrology of the GDS, negatively affecting its ecosystem structure and function. To restore a seasonally flooded, saturated hydrologic regime to portions of the swamp, adjustable water control structures (WCS) were installed at strategic locations within existing drainage ditches. The objective of this study was to determine if the installation of the WCSs significantly altered the hydropatterns of two target restoration areas, resulting in hydrologic conditions comparable to nearby reference sites with desired forest communities. The water table (WT) was monitored for three years prior to WCS installation (pre-WCS) and three years after WCS installation (post-WCS). Comparison of WT data from the pre and post-WCS periods, using jurisdictional wetland criteria and empirical cumulative distribution functions (ECDFs), indicated increased saturated conditions within the target restoration areas following installation of the WCS. Paired Before-After Control-Impact (BACIP) statistical analysis revealed the WCS installation had a significant positive impact on WT levels in the target restoration areas relative to the reference sites. Hydrologic restoration will aid the effort to restore target forest communities within the swamp, reduce fire susceptibility, prevent peat oxidation, maintain carbon storage, and reduce non-target vegetation competition.