Abstract
Abstract. The southeastern United States hosts extensive forested wetlands, providing ecosystem services including carbon sequestration, water quality improvement, groundwater recharge, and wildlife habitat. However, these wetland ecosystems are dependent on local climate and hydrology, and are therefore at risk due to climate and land use change. This study develops site-specific empirical hydrologic models for five forested wetlands with different characteristics by analyzing long-term observed meteorological and hydrological data. These wetlands represent typical cypress ponds/swamps, Carolina bays, pine flatwoods, drained pocosins, and natural bottomland hardwood ecosystems. The validated empirical models are then applied at each wetland to predict future water table changes using climate projections from 20 general circulation models (GCMs) participating in Coupled Model Inter-comparison Project 5 (CMIP5) under the Representative Concentration Pathways (RCPs) 4.5 and 8.5 scenarios. We show that combined future changes in precipitation and potential evapotranspiration would significantly alter wetland hydrology including groundwater dynamics by the end of the 21st century. Compared to the historical period, all five wetlands are predicted to become drier over time. The mean water table depth is predicted to drop by 4 to 22 cm in response to the decrease in water availability (i.e., precipitation minus potential evapotranspiration) by the year 2100. Among the five examined wetlands, the depressional wetland in hot and humid Florida appears to be most vulnerable to future climate change. This study provides quantitative information on the potential magnitude of wetland hydrological response to future climate change in typical forested wetlands in the southeastern US.
Highlights
Wetlands provide ecosystem services such as groundwater recharge, water quality improvement, flood control, carbon sequestration, wildlife habitat, and recreation (Hammack and Brown, 2016; Richardson, 1994)
The objectives of this study were to (1) construct and validate empirical models of wetland groundwater dynamics using long-term observational data in five typical southern forested wetlands; (2) forecast water table changes in the five wetlands under 40 climate change scenarios (i.e., 20 general circulation models (GCMs) and two CO2 emission pathways); and (3) investigate the key mechanisms driving the impacts of climate change in southern forested wetlands
The results show that the models performed reasonably well for all five wetlands, and could be used to predict future changes in water table level due to climate change
Summary
Wetlands provide ecosystem services such as groundwater recharge, water quality improvement, flood control, carbon sequestration, wildlife habitat, and recreation (Hammack and Brown, 2016; Richardson, 1994). The importance of water table level in regulating ecosystem function has long been recognized (Sun et al, 2000). Water table level controls biogeochemical cycles and emissions of greenhouse gases such as CH4, CO2, and NOx, and has an influence on regional and global climate (Paschalis et al, 2017). Zhu et al.: Modeling the Potential Impacts of Climate Change small change (less than 10 cm) in wetland water table level may have profound impacts on wetland structure and other ecosystem functions (Webb and Leake, 2006)
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