ABSTRACT
Alessandra Marzadri1 & Alberto Bellin2 1Center for Ecohydraulics Research, University of Idaho, Boise, ID, United States 2Department of Civil, Environmental and Mechanical Engineering, University of Trento,Trento, Italy
ABSTRACT
Several studies have shown the importance of microbial processes in removing nitrogen from rivers, with first-order gravel bed streams playing a major role in reducing the total load. Consequently, modelling transport of nutrients and contaminant in rivers calls for including temporary storage and nitrification-denitrification processes within hyporheic and riparian zones. In gravel bed rivers alternate zones of high and low pressure generated by bedforms induce a complex flow pattern within the hyporheic zone that interacts with the stream through downwelling and upwelling zones. The two transport equations for NH+4 and NO
− 3 were solved, coupled
with the chained first-order kinetics modelling nitrification and denitrification processes within the hyporheic zone, by using a Lagrangian approach and assuming that dispersion is negligible. With this simple, yet powerful, model the interplay between streambed morphology and nitrogen removal from hyporheic zone of a gravel bed river including the interplay between ammonium and nitrate were studied.
