Method to Assess Climate Change Impacts on Hydrologic Boundaries of Individual Wetlands

Potential impacts of climate change on the position of the wetland-hydrology boundary were estimated for four sites in the Eastern U.S. Precipitation and temperature predictions were obtained from the Hadley general circulation model (UKMO-HadCM3) because it most closely approximated observed precipitation for the period 1950–2000. The DRAINMOD hydrologic model was used to compute daily water table levels over two time periods: 1983–2012 (current conditions) and 2041–2070 (future conditions). For each site and time period, the model simulated water table depths for a soil pedon (Typic Paleaquult) that previous work demonstrated was on the wetland-hydrology boundary. Results for the Pitt County site in NC showed that by 2070 the wetland-hydrology boundary would have moved “downhill” to a point that was approximately 17 cm lower in elevation than where the boundary was in 2012 due to a 20% increase in evapotranspiration. Similar analyses were done for hypothetical wetland soils in Miami FL, Easton MD, and Portland ME where the wetland hydrology boundaries were estimated to drop in elevation by 5, 10 and 25 cm, respectively. Our results demonstrated that climate change may have significant impact on wetland boundaries.