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Water Temperature changes in the Mississippi River Basin
Citation:
Tang, C., R. Dennis, AND E. Cooter. Water Temperature changes in the Mississippi River Basin. Internal Presentation, RTP, NC, July 23, 2015.
Impact/Purpose:
The National Exposure Research Laboratory’s Atmospheric Modeling Division (AMAD) conducts research in support of EPA’s mission to protect human health and the environment. AMAD’s research program is engaged in developing and evaluating predictive atmospheric models on all spatial and temporal scales for forecasting the Nation’s air quality and for assessing changes in air quality and air pollutant exposures, as affected by changes in ecosystem management and regulatory decisions. AMAD is responsible for providing a sound scientific and technical basis for regulatory policies based on air quality models to improve ambient air quality. The models developed by AMAD are being used by EPA, NOAA, and the air pollution community in understanding and forecasting not only the magnitude of the air pollution problem, but also in developing emission control policies and regulations for air quality improvements.
Description:
In this study, we demonstrate the transfer of a physically based semi-Lagrangian water temperature model (RBM) to EPA, its linkage with the Variable Infiltration Capacity (VIC) hydrology model, and its calibration to and demonstration for the Mississippi River Basin (MRB). The results of this off-line coupling compare favorably with observed water temperature data at river gages throughout the MRB. Further sensitivity analysis shows that mean water temperatures increase by 1.3○C, 1.5○C, and 1.8○C in northern, central and southern MRB zones, respectively, under a hypothetical uniform air temperature increase of 3○C. If air temperatures increase uniformly by 6○C in this scenario, then water temperatures are projected to increase by 3.3○C, 3.5○C and 4.0○C. We expect water temperatures to increase as air temperatures warm under climate change. These warmer fresh water conditions could affect water quality, ecosystem health, and electric power plant generation efficiency, including the ability to meet stream discharge standards at those power plants. Lastly, downscaled air temperatures from a global climate model are used to drive the coupled VIC and RBM model from 2020 to 2099. Considering only changes to air temperature, 2020 to 2099 average stream temperatures may increase by 1–8○C above 1950 – 2010 average water temperatures, with non-uniform increases along the river. In some portions of the MRB, stream temperatures could increase above survival thresholds for several native fish species during summer. Follow-on research will
URLs/Downloads:
FINAL_WATER_TEMPERATURE.PDF (PDF, NA pp, 7599.779 KB, about PDF)WATERTEMPERATURE2.PDF (PDF, NA pp, 7650.02 KB, about PDF)