IAHR, founded in 1935, is a worldwide independent member-based organisation of engineers and water specialists working in fields related to the hydro-environmental sciences and their practical application. Activities range from river and maritime hydraulics to water resources development and eco-hydraulics, through to ice engineering, hydroinformatics, and hydraulic machinery.
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You are here : eLibrary : IAHR World Congress Proceedings : 35th IAHR Congress - Chengdu (2013) : THEME 4 - HYDRO-ENVIRONMENT : Dune Morphology Control on Redox Conditions Within the Hyporheic Zone
Dune Morphology Control on Redox Conditions Within the Hyporheic Zone
Author : Alessandra Marzadri, William J Reeder, Daniele Tonina and Alberto Bellin
River morphology has a direct impact on stream nutrient removal and transport because of its influence on the hyporheic hydraulics. Microbially mediated transformations such as nitrification and denitrification processes that occur within the streambed sediment depend on the amount of reactants transported into the sediment. The interaction between stream flow and streambed topography regulates the hyporheic fluxes and thus affects the biogeochemical processes occurring in the sediment. Here we investigate the control by dune-like bed forms and flow on prevailing aerobic and anaerobic conditions within the streambed hyporheic zone. We apply a new Damk”hler number, D , which is defined as the a ratio between the median hyporheic residence time and the time to consume dissolved oxygen to a prescribed threshold concentration below which anaerobic conditions are present, i.e. D = t \t . a up,50 lim Values of D larger than 1 indicate prevailing anaerobic conditions, whereas values smaller than 1 a prevailing aerobic conditions, within the hyporheic sediment. Our results show a direct relationship between dune shape, ratio between dune amplitude and wavelength, streambed depth and flow velocity on D and consequently on the volume of the hyporheic sediment in aerobic and anaerobic conditions. a
File Size : 281,970 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 35th IAHR Congress - Chengdu (2013)
Article : THEME 4 - HYDRO-ENVIRONMENT
Date Published : 18/07/2016
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