River Engineering

Rivers are the backbones of the vulnerable river deltas that host major portions of the world population. They are also the arteries of wetlands with the world’s richest biodiversity. Rivers supply water and construction aggregates, and they form ecological corridors and economical axes of transportation. However, rivers also cause havoc when their floods engulf the surrounding land. River engineering serves society by optimizing the numerous benefits while providing protection against flooding.

River works are among the oldest feats of engineering since the times of Chinese Emperor Yu and Egyptian Pharaoh Menes. Today, river managers and engineers are faced with the task of reconciling and optimizing the different aspects of safety, water supply, construction aggregates, navigation, hydropower and ecosystem functioning. These are the ‘functions’ of a river in the words of engineers and the ‘ecosystem services’ in the words of ecologists. The Chair of River Engineering studies and teaches measures to enhance these functions, as well as methods to assess the near-field and far-field effects of these measures, on a short term and in the long run.

The chair has a strong foundation in principles of fluid mechanics and sediment transport, developing and using mathematical codes in the SOBEK and Delft3D modelling systems. At the same time, it maintains a firm basis in field experience and laboratory experiments. The chair is manned by a dedicated staff of river engineers who worked on the Rhine branches, the Meuse, the Yangtze, the Brahmaputra, the Ganges, the Amazon, the Nile, the Colorado and many other rivers around the globe. Having close links to Deltares and Rijkswaterstaat, the staff is involved in the Room for the River programme, implementation of the European Water Framework Directive, the DVR project for sustainable river waterways and studies of climate adaptation. Key areas of fundamental research include the transport of graded sediment, the biogeomorphology of floodplains, detailed morphodynamics including the effects of larges eddies and turbulence, river bifurcations, and the hydraulic and morphological effects of river training structures.

An MSc project in 2009 dealt with the formation and the lifetime of sand bars and beaches along the Colorado River in the Grand Canyon, USA. These bars and beaches are important for fish as well as for camping, but they have been disappearing due to erosion since hydropower projects changed the river’s discharge regime. Searching for ways to restore these bars and beaches, the US Geological Survey carried out a controlled flood experiment in March 2008. Staff and students of the chair were involved in the project as the only non-Americans, because Delft3D was recognised as the most advanced model available. Important model features in this context are large-eddy simulation and the erosion, transport and deposition of graded sediments.

Another MSc project in 2009 regarded sediment nourishment in the river Rhine at Iffezheim, near Karlsruhe, Germany, in close collaboration with the Bundesanstalt für

Gewässerkunde. Similar nourishments are currently in preparation for the Bovenrijn reach of the Rhine in the Netherlands, where ongoing bed degradation is about to create problems for navigation, floodplain habitats and the stability of structures. The MSc student used field data from Germany to verify the capabilities of a two-dimensional morphological model based on Delft3D and to formulate practical recommendations for sediments nourishments in the Bovenrijn. One of the staff members sits on the Fluvial Hydraulics Committee of the International Association of Hydraulic Engineering and Research, which is the leading international forum for research in river engineering. The chair also plays an active role in the Netherlands Centre of River Studies, with frequent collaboration with UNESCO-IHE and the universities of Utrecht, Twente and Wageningen. The chair recently started joint research with the faculty of Aerospace Engineering at Delft University of Technology to develop and test methods of underwater bed sediment grain size observations using multibeam echosounder backscatter.