Impact of climate change and climate anomalies on hydrologic and biogeochemical processes in the Chesapeake Bay Watershed

Authors: WAGENA, MOGES - Virginia Tech; COLLICK, AMY - University Of Maryland Eastern Shore (UMES); ROSS, ANDREW - Pennsylvania State University; RAU, BENJAMIN - University Of Maryland Eastern Shore (UMES); SOMMERLOT, ANDREW - Virginia Tech; FUKA, DANIEL - Virginia Tech; NAJJAR, RAYMOND - Pennsylvania State University; Kleinman, Peter; EASTON, ZACHARY - Virginia Tech

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2018
Publication Date: 6/1/2018
Citation: Wagena, M.B., Collick, A., Ross, A.C., Rau, B., Sommerlot, A., Fuka, D.R., Najjar, R.G., Kleinman, P.J., Easton, Z.M. 2018. Impact of climate change and climate anomalies on hydrologic and biogeochemical processes in the Chesapeake Bay Watershed. Science of the Total Environment. 637-638:1443-1454. https://doi.org/10.1016/j.scitotenv.2018.05.116.
DOI: https://doi.org/10.1016/j.scitotenv.2018.05.116

Interpretive Summary: USDA’s experimental watersheds have long served as a test bed for new technologies to improve the management of water resources in agriculture. This study evaluated the consequences of changing weather patterns hydrology and water quality in one of USDA’s experimental watersheds in the Chesapeake Bay region. Results suggest that changing weather with affect water quality in agricultural watersheds, requiring shifts in management strategies used today.

Technical Abstract: Diffuse nutrient pollution from agricultural landscapes is a priority water quality concern and the cause of mitigation activities worldwide. Climate change and climate variability impact hydrology, nutrient cycling, and ultimately water quality, which can complicate mitigation measures. Climate change can also influence greenhouse gas (GHG) emissions by changing stoichiometric nutrient ratios, soil moisture, and soil temperature, all controls of microbially mediated emissions. This research quantifies the impact of climate change and climate anomalies on hydrology, nutrient cycling, and greenhouse gas (GHG) emissions in an agriculturally dominated Chesapeake Bay watershed. We initialize the Soil and Water Assessment Tool-Variable Source Area model using a multi-year management database of individual agricultural fields in the WE-38 research watershed in central Pennsylvania. We force the calibrated model with seven downscaled and bias-corrected regional climate models for a historic period (1975 -1998) and a future period (2045-2068) and derived climate anomalies to assess the impact of climate change on hydrology, nitrate-N (NO3-N), phosphorus (P), and sediment export, and on emissions of nitrous oxide (N2O) and di-nitrogen (N2). Results indicate that climate change, through an increase in precipitation, will result in increases in winter/spring flow (4.9%) and the subsequent increase in export of mineral P (27.3%), total P (21.7%), sediment (27.2%), N (0.85%), N2O(17.7%), and N2(28.6%). Conversely, decreases in summer flow (-17.3%) and the export of mineral P (-20.1%), total P (-18.5%), sediment (-15.0%), NO3-N (-12.2%) are driven by greater evapotranspiration, which result from increasing summer temperatures and increases in N2O (18.1%0 and N2 (12%). On a mean annual basis increases in flow (2.9%), sediment (7%), NO3-N (2.5%) and mineral P (8.1%), total P (4.8%) export, and N2 (28.2%), and N2O (20.0%) emissions are forecast. While the changes in flow are related directly to changes in precipitation and temperature, the changes in nutrient and sediment export are, to some extent, driven by changes in agricultural management that climate change induces, for instance, earlier spring tillage and altered nutrient application timing. These results suggest that climate change will influence water quality and GHG emissions in the Chesapeake Bay region perhaps making it more difficult to meet water quality goals for the region.