title: Hydrogeologic Processes Impacting Storage, Fate, and Transport of Chloride from Road Salt in Urban Riparian Aquifers.
abstract: Detrimental effects of road salt runoff on urban streams are compounded by its facilitated routing via storm drains, ditches, and flood channels. Elevated in-stream salinity may also result from seasonal storage and discharge of chloride in groundwater, and previous work has hypothesized that groundwater discharge to streams may have the effect of diluting stream chloride concentrations in winter and enriching them in summer. However, the hydrogeological processes controlling these patterns have not been thoroughly investigated. Our research focuses on an urban stream and floodplain system in Syracuse, NY, to understand how groundwater and surface water exchange impacts chloride storage, fate, and transport. We created a 3D groundwater flow and solute transport model of the floodplain, calibrated to the distributions of floodplain hydraulic heads and groundwater fluxes to the stream throughout the reach. We used a sensitivity analysis to calibrate and evaluate the influence of model parameters, and compared model outputs to field observations. The main source mechanism of chloride to the floodplain aquifer was high-concentration, overbank flood events in winter that directly recharged groundwater. The modeled residence time and storage capacity of the aquifer indicate that restoration projects designed to promote floodplain reconnection and the frequency of overbank flooding in winter have the potential to temporarily store chloride in groundwater, buffer surface water concentrations, and reduce stream concentrations following periods of road salting.
authors.affiliation: Department of Earth Sciences, Syracuse University , 204 Heroy Geology Laboratory, Syracuse, New York 13244, United States.
authors.forename: Sarah H
authors.initials: SH
authors.lastname: Ledford
authors.affiliation: Department of Earth Sciences, Syracuse University , 204 Heroy Geology Laboratory, Syracuse, New York 13244, United States.
authors.forename: Laura K
authors.initials: LK
authors.lastname: Lautz
authors.affiliation: Department of Forest and Natural Resources Management, College of Environmental Science and Forestry, State University of New York , One Forestry Drive, Syracuse, New York 13210, United States.
authors.forename: John C
authors.initials: JC
authors.lastname: Stella
mesh_terms: D004784:Environmental Monitoring; D055868:Floods; D060587:Groundwater; D045483:Rivers; D012965:Sodium Chloride; D014872:Water Movements
chemical_list: D012965:Sodium Chloride