H022-11
Simulating Flood-Induced Contaminated Soil and Sediment Transport with a Coupled HEC-RAS 2D and WASP Model

Monday, 7 December 2020: 18:00
Virtual
Afshin Shabani, Oak Ridge Institute for Science and Education, Oak Ridge, TN, United States; Postdoctoral Researcher at Oak Ridge Institute for Science and Education, Oak Ridge, TN, United States, Sean Woznicki, Assistant Professor, Annis Water Resources Institute, Grand Valley State University, Allendale, United States, Megan Mehaffey, Research Ecologist, Environmental Pathways Modeling Branch, Public Health and Environmental Systems Division, Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Durham, NC, United States, Myla Ramirez, Research Scientist, Site Remediation and Waste Management Program,NJ Department of Environmental Protection, Trenton, NJ, United States, Lauren Drumm, NJ Department of Environmental Protection, New Jersey, United States, Ricardito Vargas, Project Manager, Land, Chemical and Redevelopment Division Region 2, US Environmental Protection Agency, New York City, NY, United States, Diana Cutt, Superfund Technical Liaison, Office of Research and Development, US Environmental Protection Agency, New York City, NY, United States and Pai-yei Whung, Senior Scientist, Center for Environmental Measurements and Modeling, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, United States
Abstract:
Increased intensity and frequency of floods raises concerns about release and transport of soil and sediment and associated contaminants to and from streams and rivers. To model these processes during flooding events, we developed an external coupler in Python to link the Hydrologic Engineering Center-River Analysis System (HEC-RAS) 2D hydrodynamic model to the Water Quality Analysis Simulation Program version 8.4 (WASP). The external coupler aggregates flow and conserves mass when transitioning from HEC-RAS 2D to WASP. We applied the coupled model to simulate soil and sediment contaminants’ (i.e., arsenic (As), lead (Pb), benzo(a)pyrene (B(a)P) fate and transport for a 100-yr flood event in Woodbridge Creek, NJ. The sensitivity analysis of WASP sediment transport simulation showed that shear stress is the parameter with the most influence on the erosion and deposition processes. The surface sediment volume at the end of a 48-hr flood simulation ranged from a net loss of 661 m3 to a net gain of 291 m3 for each model segment (50 m). Change in surface sediment concentrations of As, Pb and B(a)P in the 100-year flood ranged from -16 to 2.8 mg kg-1, -266­­ to 16 mg kg-1, and -1.3 to 0.6 mg kg-1, respectively depending on model segment. Results demonstrate that there is significant potential for sediment-driven contaminant transport during extreme flooding, which can be quantified by the coupled models.

Keywords: Flood, Sediment and Contaminant transport, Hydrodynamic Linkage, Water Quality

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