Grantee Research Project Results
Predicting Impacts of Rerouting Drainage Water From the Pamlico Sound to Restored Wetlands—A Critical Component to Galvanize Stakeholder CooperationEPA Grant Number: FP917483
Title: Predicting Impacts of Rerouting Drainage Water From the Pamlico Sound to Restored Wetlands—A Critical Component to Galvanize Stakeholder Cooperation
Investigators: Messer, Tiffany L
Institution: North Carolina State University
EPA Project Officer: Jones, Brandon
Project Period: August 16, 2012 through August 15, 2015
Project Amount: $126,000
RFA: STAR Graduate Fellowships (2012)
Research Category: Academic Fellowships , Fellowship - Bio-Environmental Engineering
Wetland restoration project partners need to know with certainty that drainage water moving from the restoration site will not impose negative hydrologic and water quality impacts downstream. Previous studies in the Albemarle-Pamlico peninsula in North Carolina have reported wetlands receiving agricultural drainage water to store water while reducing nutrients, sediment and fecal bacteria. However, controlled experiments have been difficult to complete, and wetland effectiveness is variable depending on such factors as soil type, loading rate and wetland to watershed ratio, which has made stakeholders hesitant to enroll land for wetland restoration projects. This research will determine with confidence the maximum hydraulic and nitrogen loads that can be diverted from the Pamlico Sound without negatively impacting downstream areas through the combination of field and wetland mesocosm observations coupled with modeling efforts. Additionally, socio-economic attitudes of project partners will be documented as this project progresses to determine how to build stronger bonds between stakeholders.Approach:
Six large wetland mesocosms containing two excavated wetland soils from future wetland sites in eastern North Carolina have been constructed in a greenhouse. Twenty-four batch studies will be conducted over a 2-year period in the mecososms with nitrogen pollutant loads typical of agricultural drainage water. Hourly nitrogen (N), carbon and dissolved oxygen concentrations and yearly biomass and soil samples will be monitored. Differences in nitrogen removals will be determined using a mass balance approach. Hydrologic monitoring and modeling efforts at the restoration site will be completed using water table elevation data loggers and water quality grab samples. Water table data, along with soil, crop and climatic data, will be used to calibrate the hydrologic model DRAINMOD to predict the volume of drainage water that can be pumped from the agricultural fields into the planned wetland restoration areas. The model will be validated by comparing predicted water levels to those measured in the wetland. Predicted N concentrations, from the model, will be compared to measured N concentrations at the inlet and outlet of the wetland mesocosms.Expected Results:
Denitrification, a microbially mediated transformation of nitrate to nitrogen gas that escapes from the wetland to the atmosphere, has been identified as the primary pathway for nitrogen removal in wetlands. Requirements for denitrification, which include anoxic conditions, carbon sources, suitable temperature and suitable pH conditions, are found in wetlands in the southeastern United States during most of the year. Therefore, nitrogen is expected to assimilate at a high level through physical and biogeochemical transformations while drainage water flows through the restored wetlands and will be significantly affected by carbon availability, nitrogen loading and water table fluctuations. Additionally, the completion of this project could lead to changes in local perceptions of conservation groups by the agricultural community, which may further lead to partnerships on larger projects that will have huge impacts on both coastal and economic conditions in eastern North Carolina and other coastal communities.
Potential to Further Environmental/Human
The restoration project in this study has the potential to become the largest project of its type in North Carolina, and significantly improve water quality in the prime shellfish waters of the Pamlico Sound. This research project will be instrumental in galvanizing stakeholders with differing attitudes on wetland restoration success, and maximize the project’s impact. Lost oyster beds and wetland hydrology could be recovered due to improvements in water quality and hydrology from this and future projects. Improvements in the ecology of the sound and adjacent forest, reduced fire risks and pumping costs, and a boost in the region’s economy could be additional impacts. Findings will advance the scientific understanding of innovative ways to manage coastal resources, and will be utilized in outreach activities, such as extension workshops and community events, to solidify critical partnerships. This project could become a national model for how large-scale environmental projects can avoid sacrificing agricultural production while resulting in win-win projects for landowners, local citizens and the environment.
wetland restoration, denitrification, DRAINMOD