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Evaluating relative sensitivity of SWAT-simulated nitrogen discharge to projected climate and land cover changes for two watersheds in North Carolina, USA
Gabriel, M., Chris Knightes, E. Cooter, AND R. Dennis. Evaluating relative sensitivity of SWAT-simulated nitrogen discharge to projected climate and land cover changes for two watersheds in North Carolina, USA. Hydrological Processes. John Wiley & Sons, Ltd., Indianapolis, IN, , online, (2015).
We investigated how projected changes in land cover and climate affected simulated nitrate (NO3−) and organic nitrogen (ORGN) discharge for two watersheds within the Neuse River Basin North Carolina, USA for years 2010 to 2070. We applied the Soil and Water Assessment Tool (SWAT) watershed model to predict nitrogen discharge using (1) atmospheric carbon dioxide (CO2) concentrations predicted by the Intergovernmental Panel on Climate Change (IPCC), (2) land cover change predicted by the Integrated Climate and Land Use Change (ICLUS) project and (3) precipitation and temperature simulated by two statistically downscaled and bias-corrected Global Circulation Models (GCMs). We determined the sensitivity of simulated nitrogen discharge to separate changes in each treatment ( CO2,  land cover, and  precipitation and temperature (PT)) by comparing each treatment to a reference condition. Results showed nitrogen discharges were most sensitive to changes in PT over the 60-year simulation. Nitrogen discharges had similar sensitivities to the CO2 and land cover treatments which were only one-tenth the influence of the PT treatment. Under the CO2 treatment, nitrogen discharges increased with increasing ambient CO2. NO3− discharge decreased with increased urbanization; however, ORGN had a varied response. Under the PT treatment, there was high spatial variability in nitrogen discharges. In a single year, certain sub-basins showed an 80% increase in nitrogen discharge relative to reference, while others showed a 400% decrease. With nitrogen discharge showing high sensitivity to PT change, we suggest more emphasis should be placed on investigating impacts of PT on nutrient transport in the Neuse River Basin. This article is protected by copyright. All rights reserved.
Published in the journal, Hydrological Processes.
Record Details:Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL EXPOSURE RESEARCH LAB
ECOSYSTEMS RESEARCH DIVISION