Can the role of macrophytes on downstream C-N-P-Si fluxes in river basins be neglected? An integrated measurement, experimental and model approach quantifying direct and indirect vegetation effects.

It is known that water plants interact with flow and can therefore significantly influence hydrological and biogeochemical processes. Numerical models are mathematical tools to integrate large amount of data to understand complex processes in river ecosystems. Yet very few of the existing models are capable of implementing aquatic vegetation and their role is mostly neglected. The current project, called FLASHMOB (FLuxes Affected by Stream Hydrophytes: Modelling Of Biogeochemistry), proposes a unique combination of a Belgian-Austrian team to combine expertise in numerical modelling with fieldwork and lab experiments. We hypothesize that the interaction between plants (in-stream vegetation) and water flow (hydrodynamic conditions) is key in determining production, downstream transport/retention and transformation of organic matter and associated nutrients. An existing model (DELWAQ) was adapted to floodplain sections of the Danube River and forms the ideal basis for integrating the role of water plants in river systems. Organic matter dynamics and aquatic primary production in the current model are coupled to dynamic surface exchange conditions. The first step is to implement the role of in-stream vegetation in a more explicit way including feedback processes through a stepwise and iterative work plan calculating the specific effects of each aspect of plant-flow interaction separately. Finally, all steps are combined and the total net effect of in-stream vegetation on water quality and –quantity of larger river sections (sub basin scale) can be quantified and used for predictions of future development of river ecosystems.

Keywords:MACROPHYTES

Disciplines:Biochemistry and metabolism, Medical biochemistry and metabolism

Project type:Collaboration project