title: Numerical study of wave effects on groundwater flow and solute transport in a laboratory beach.
abstract: A numerical study was undertaken to investigate the effects of waves on groundwater flow and associated inland-released solute transport based on tracer experiments in a laboratory beach. The MARUN model was used to simulate the density-dependent groundwater flow and subsurface solute transport in the saturated and unsaturated regions of the beach subjected to waves. The Computational Fluid Dynamics (CFD) software, Fluent, was used to simulate waves, which were the seaward boundary condition for MARUN. A no-wave case was also simulated for comparison. Simulation results matched the observed water table and concentration at numerous locations. The results revealed that waves generated seawater-groundwater circulations in the swash and surf zones of the beach, which induced a large seawater-groundwater exchange across the beach face. In comparison to the no-wave case, waves significantly increased the residence time and spreading of inland-applied solutes in the beach. Waves also altered solute pathways and shifted the solute discharge zone further seaward. Residence Time Maps (RTM) revealed that the wave-induced residence time of the inland-applied solutes was largest near the solute exit zone to the sea. Sensitivity analyses suggested that the change in the permeability in the beach altered solute transport properties in a nonlinear way. Due to the slow movement of solutes in the unsaturated zone, the mass of the solute in the unsaturated zone, which reached up to 10% of the total mass in some cases, constituted a continuous slow release of solutes to the saturated zone of the beach. This means of control was not addressed in prior studies.
authors.affiliation: Center for Natural Resources Development and Protection, Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ 07102, United States.
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Geng
authors.affiliation: Center for Natural Resources Development and Protection, Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ 07102, United States. Electronic address: boufadel@gmail.com.
authors.forename: Michel C
authors.initials: MC
authors.lastname: Boufadel
authors.affiliation: Changjiang River Scientific Research Institute (CRSRI), Changjiang Water Resources Commission of MWR, Wuhan 430010, China.
authors.forename: Yuqiang
authors.initials: Y
authors.lastname: Xia
authors.affiliation: School of Water Resources and Environmental Science, China University of Geoscience-Beijing, Beijing 100083, China.
authors.forename: Hailong
authors.initials: H
authors.lastname: Li
authors.affiliation: Center for Natural Resources Development and Protection, Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ 07102, United States.
authors.forename: Lin
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102, United States.
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Jackson
authors.affiliation: Department of Mechanical Engineering, Clemson University, Clemson, SC 29634-0921, United States.
authors.forename: Richard S
authors.initials: RS
authors.lastname: Miller
mesh_terms: D001493:Bathing Beaches; D004784:Environmental Monitoring; D060587:Groundwater / Q000032:analysis*; D057446:Hydrodynamics; D008962:Models, Theoretical; D012623:Seawater / Q000032:analysis*; D012822:Silicon Dioxide / Q000737:chemistry*; D012996:Solutions / Q000032:analysis; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D012996:Solutions; D014874:Water Pollutants, Chemical; D012822:Silicon Dioxide
keywords: Groundwater flow; Laboratory beach; MARUN numerical model; Tracer; Waves