Quantifying and modelling interactive GRADients in VEGetation-hydrodynamic systems: the key to an improved prediction of aquatic system resilience to environmental change (GRADVEG)

• Applicant: Maike Paul, Ph.D.
• Subject Area: Ecology and Biodiversity of Plants and Ecosystems ; Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 258393347

The interaction of vegetation with waves and flow is getting more and more attention, especially in the light of potential benefits for shore protection measures in coastal and riverine areas. Buoyancy and stiffness are considered important parameters on the individual plant level that influence plant motion under hydrodynamic forcing and consequently energy dissipation by vegetation. For vegetation meadows, biomass is proposed as key parameter for the description of wave attenuation. However, the influence of individual plant parameters on wave and flow attenuation is not yet fully understood. Moreover, information is lacking how a non-uniform vertical distribution of vegetation properties affects hydraulic resistance. This project therefore aims at quantifying the effect of stiffness, buoyancy and biomass and their gradients along the plant height on bio-physical interactions. Within the project, the natural range of these vegetation parameters will be established and related to the hydrodynamic conditions a population grows in. Additionally, the effect of changing physical parameters (e.g. salinity) and parasite colonisation on a plant's mechanical condition will be evaluated. Based on the established parameter range, surrogates with different gradients of the three key parameters will be developed and used to carry out a detailed laboratory study. During the experiments, both the individual plant as well as the meadow scale will be addressed. Measurements will cover the flow field around the vegetation and the vegetation response to hydrodynamic forcing including drag. The physical experiments will be supported by a numerical study to explore relevant parameter ranges. In return, the laboratory measurements will provide validation data for a further development of the numerical model. Moreover, velocity and drag measurements will be carried out at selected field sites to assess how well the results from the surrogate study can be transferred to natural vegetation. Hydrodynamic conditions under investigation will include waves, currents and a combination of waves and currents to cover the whole range of natural hydrodynamic conditions and hence make the study's outcomes widely applicable.

• DFG Programme: Research Grants