The PhD topic will focus on the study of the interaction between waves and currents and flexible bodies, such as seagrass plants, to develop Coastal Defense systems based on the principles of 'Building with Nature'. Sustainable coastal protection and mitigation of flooding and erosion hazards using coastal defense structures with low environmental impact is of great importance in the adaptation process towards global climate change and sea-level rise. Coastal ecosystems like salt marsh vegetation and seagrass meadows can play an important role in dissipating energy from waves and currents, while at the same time they provide high ecological and economical values. Within this research, pioneering large-scale 3D experiments will be executed in a state-of-the-art new wave tank in Belgium with seagrass, establishing a database for numerical and theoretical validation and for fundamental understanding of the waves-current-vegetation interaction. A CFD-based solver and an analytical model dealing with waves-current-vegetation interaction will be developed.