Author(s): Jiaming Liu; Yang Xiao; Carlo Gualtieri
Linked Author(s): Carlo Gualtieri, Yang Xiao
Keywords: No keywords
Abstract: The hyporheic zone is the volume within streambed where stream water and surface water mix. In a compound channel, as floodplains are submerged, solutes in the water column enter the hyporheic zone and react with the solutes upwelling from the groundwater. Those reactive processes, such as aerobic respiration, nitrification, and denitrification, still need to be clarified. In this paper, a 3D hydrodynamic model coupled to a 2D groundwater and biogeochemical model was applied to investigate the effect of bank slope angle and ambient groundwater discharge on such processes. A denitrification zone was found below the floodplain for bank slope angle = 90°, being elongated in the horizontal direction with smaller angles. Furthermore, a lower angle of the bank slope decreased N entering the streambed and increased nitrogen removal. A decrease in ambient groundwater affected negatively both aerobic respiration and denitrification reactions. The model becomes a source of NO3 at ambient groundwater flows less than -0.9 m/d. At the end, those results demonstrated that bank slope angle and ambient groundwater discharge significantly affect solute transport and biogeochemical processes in the hyporheic zone of a compound channel.
Year: 2022