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By Leon de Jongste and Michel Zuijderwijk, Witteveen+Bos.

These questions were the main driver to organize a knowledge sharing meeting with Witteveen+Bos at February 15th 2019, prepared in collaboration with RiverCare coordinator dr. Ralph Schielen. Witteveen+Bos is one of the partners in RiverCare. During a half-day session, six RiverCare researchers presented their work to experts of Witteveen+Bos with a background in hydrodynamics, morphology, water management and data science. A lively discussion ensued after each presentation. Chairman Maarten Jansen had to move a number of questions to the break as not to run too far out of time. The monumental Rotterdam office and excellent view over the Nieuwe Maas added to the vibrant atmosphere.

River dynamics specialist in Witteveen+Bos, Michel Zuijderwijk gave a presentation on the diversity of river engineering projects at Witteveen+Bos. His experience from Danube River training and dredging works and his involvement in many Dutch river projects in all kind of project phases, showed the versatility of our work. He also highlighted the role of our team in various river projects such as, the Development of the Bangladesh Delta Plan 2100 and the Feasibility study for a bypass of the Itaipu Dam in Paraguay/Brazil.

Menno Straatsma’s vision on intercomparing design alternatives gave a lot of recognition, as in environmental impact assessments it is often difficult to score and compare very different alternatives in a balanced way. Menno Straatsma also showed RiverScape; a Quick Assessment tool for interventions in rivers. RiverScape fits very well in the philosophy of CoDes, a Coastal Design Tool developed and applied by us.

The bank erosion measurements of Gonzalo Duró proved the potential of motion photogrammetry through the use of drones. This technique seems very suitable to us for surveying poorly accessible floodplains and river banks.

How to deal with uncertainty in models and data remains a challenge in our field. Koen Berends argued that a higher relative uncertainty requires more overdesigned interventions to achieve the same effect at the same level of confidence. We noticed that dealing with uncertainties is currently not part of the assessment of effectiveness of interventions taken in the Dutch river systems. This research will help to address uncertainty in (integrated) river management.

Pepijn van Denderen showed us a classification of the morphodynamics of side channels. This is relevant to the lifespan, design and maintenance of the side channels.

We are pleased with the implementation of the work of Victor Chavarrias on ill-posedness in morphodynamic models in Delft3D, as presented. During a upcoming workshop with users, he will demonstrate us both the problem analysis and the modelling strategies to overcome these problems. We are convinced that his research will contribute to the improvement of modelling river morphodynamics in new projects.

Last but not least, Timo de de Ruijsscher showed results of his research about the sill channel geometry at the side channel intake of a physical scale model for the longitudinal training dam.

We look back on a very interesting and open meeting in which experience from both sides, academic and consultancy, was shared and would like to thank the involved researchers to make this event a success!