Assessment of climate-proof flood defence alternatives along the Nederrijn/Lek (HSGR07)
Because of the prospect of climate change, as well as various other changes, the boundary conditions for flood defences may be subject to changes in the future. This project therefore assessed, at various levels of detail, climate-proof flood defence alternatives for three locations along the Nederrijn/Lek that currently do not meet the standards. These alternatives should, after completion, be so robust that they will not need to be strengthened for a long time (approx. 100 years), and provide extra safety at the same time.
Transection Dike strengthening
The mission can be accomplished for a part of the village of Streefkerk by widening the dike considerably on the riverine side, giving the current dike body the function of a high supporting slope. As a result, existing buildings would not need to be demolished. From a planning perspective, the dike will keep its distinct appearance and the link between the village and the river can be strengthened. Despite its higher initial investment costs, this climate-proof design will be financially more attractive over the course of 100 years compared to the conventional solution.
Another solution, using a system with two parallel dikes, was explored for the area of Lienden. The area between the two dikes can be flooded in a controlled manner during extreme events in order to prevent any instances of piping. At the same time, the current need to strengthen the main dike will completely or partially disappear and the resulting system would be highly adaptable to changing circumstances.
The last location, Arnhem, demonstrated that realising such unconventional flood proofing alternatives requires a high level of commitment and cooperation among all stakeholders involved. All these stakeholders need to be involved from the very start and the timing of such integrated projects is consequently of crucial importance.