Abstract. The purpose of this study was to determine the elevation dynamics of a created tidal marsh on the North Carolina coast. Deep rod surface elevation tables (RSET) and feldspar marker horizons (MH) were installed in plots to measure net surface elevation changes and to quantify contributing processes. Twelve total plots were placed on four elevation gradient transects (three transects within the created marsh and one within a reference marsh), with three plots along each transect. Elevation gradient transects included a low marsh plot dominated by , a middle marsh plot dominated by , and a high marsh plot dominated by . RSET and MH were measured in December 2012, January 2014, April 2017, and March 2018. Elevation change ranged from 1.0 to 4.0 mm year-1 within the created marsh and from -0.4 to 2.0 mm year-1 within the reference marsh. When compared to the long-term linear trend in local relative sea level rise (RSLR) of 3.10 ±0.35 mm year-1, the middle marsh plots within the created marsh trended toward survival, with an observed elevation increase of 3.1 ±0.2 mm year-1. Alternatively, the low and high marsh plots within the created marsh trended toward submergence, with observed elevation increases of 2.1 ±0.2 and 1.3 ±0.2 mm year-1, respectively. These results indicate that a created marsh can display elevation dynamics similar to a natural marsh and can be resilient to current rates of RSLR if constructed with a high elevation capital. Surface elevation changes were observed over a short time period and in a relatively young marsh, so it is uncertain if these trends will continue or how the long-term relation with RSLR will develop. While this study provided initial data on the ability of created tidal marshes to respond to observed sea level rise, subsequent observations are needed to evaluate the long-term elevation dynamics. Keywords: Resiliency, Sea level rise, Surface elevation tables, Tidal marsh, Vertical accretion.

HighlightsBased on current emissions, mean water table decline in these wetlands will likely range from 25 to 65 cm by 2100.Projected changes could lead to a decline or loss of the important ecosystem services that wetlands provide to society.Results indicate a potential need to allocate more resources to developing strategies for managing wetlands.Abstract. Wetlands are especially at risk from climate change because of their intermediate landscape position (i.e., transition between upland and aquatic environments), where small changes in precipitation and/or evapotranspiration can have substantial impacts on wetland hydrology. Because hydrology is the primary factor influencing wetland structure and function, the important ecosystem services that wetlands provide may be altered or lost as a result of climate change. While a great deal of uncertainty is associated with the projected impacts of climate change on wetlands, hydrologic models and downscaled climate model projections provide tools to reduce this uncertainty. DRAINMOD is one such process-based hydrologic model that has been successfully adapted to simulate the daily water level fluctuations in natural wetlands. The objective of this project was to determine the range of possible impacts of climate change on the hydrologic regimes of non-riverine, non-tidal Coastal Plain wetlands in North Carolina. DRAINMOD models were calibrated and validated for two minimally disturbed, natural wetland sites using observed water table and local weather data. Two representative concentration pathway (RCP) scenarios were evaluated: RCP4.5 and RCP8.5. Nine models were selected from an ensemble of 32 climate models to represent the range of possible changes in mean precipitation and temperature. Downscaled climate projections were obtained from the U.S. Bureau of Reclamation. Simulations were run from 1986 to 2099, and results were evaluated by comparing the projected mean water table levels between the base period (1986-2015) and two future evaluation periods: 2040-2069 and 2070-2099. The model simulation results indicated that the projected mean water table level may decline by as much as 25 to 84 cm by the end of this century (2070-2099) for the RCP8.5 scenario and may decline by 4 to 61 cm for the RCP4.5 scenario. In Coastal Plain wetlands, declines in water tables can lead to the subsidence of organic soils, which can lead to the loss of stored carbon and increased risk of peat fires. Lower mean water levels can also lead to shifts in vegetation community composition and loss of habitat functions for wetland-dependent fauna. These results provide an overview of the potential impacts of climate change on North Carolina wetlands, and they provide a range of scenarios to inform and guide possible changes to water management strategies in wetland ecosystems that can be implemented now to limit the loss of ecosystem services over the long term. Keywords: Climate change, DRAINMOD, Hydrology, Modeling, North Carolina, Wetlands.

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