Long-Term Water Table Dynamics of Forested Wetlands: Drivers and their Effects on Wetland Hydrology in The Southeastern Atlantic Coastal Plain

Abstract

Sustainable management of forested wetlands requires an understanding of water Table (WT) dynamics affected by rainfall and evapotranspiration (ET) and management practices, designed to sustain water quality, quantity, and ecosystem functions and productivity. In this paper analysis of long-term data from four drained and six undrained sites on coastal forested wetlands showed that their growing season WT dynamics depends upon ET as affected by vegetation stand age, with undrained sites yielding deeper WT than the drained young sites but shallower than the mature ones. Wetland hydrology criterion was not met on any of the drained sites including with controlled drainage and one unditched site with moderately well-drained sandy soil, where the WT was within 30 cm of the surface for <8% of the time compared to 31% or greater on undrained sites. WT response was similar on both drained and undrained watersheds soon after vegetation removal compared to the baseline level. Similarly, the WT dynamics on all soil types and vegetation behaved similarly during extreme storms. No trend was found in limited annual mean WT data. These results may have implications for coastal wetland forest restoration and modeling studies relating wetland hydrology as affected by anthropogenic and natural disturbances.