Living with Floods: Strategy Development for Flood Management in the Rhine Basin

To contribute through research to the development of a resilient strategy for flood management in the Rhine Basin, and recommendations on how to implement such a strategy. Research covers investigating the possibilities to match increased room for the river and spatial planning behind the dikes at the lowest possible costs (damage).

The high flooding of the Rhine River in 1993 and 1995, in combination with the growing awareness of global climate change, has made the public and respective authorities realise that flood protection cannot continue to be maintained by endlessly increasing the height of dikes.

Instead, more room should be given to the river in order to allow it to discharge more water at a lower water level.

Recent studies have shown that a significant rest risk remains when the measures are limited to the floodplain and the riverbed.

The following approaches will be pursued to reach the optimal costs-benefit ratio:

• Selection of areas for additional discharge or storage with a large effect on the water level and limited damage;
• Compartmentalisation of the current dike rings by construction of additional dikes to protect areas with a high potential damage;
• Differentiation in the safety level of different (compartments of) dike rings;
• Adaptation of the land use and especially the construction of new infrastructure to the spatial needs of flood management; and
• Investigation of possibilities to combine hydraulic functions with other land use types (agriculture, nature, recreation and housing) in such a way, that all functions are enhanced.

A computational framework is being compiled to assess the flooding pattern and depth, the flood damage and the downstream effects of controlled flooding.

This framework will be based on a Geographic Information System and one and two dimensional hydraulic models. For the evaluation of different alternatives the cost-benefit ratio is not the only criterion. Other criteria such as robustness flexibility, economic development, and protection and development of landscape, natural and cultural values will also be taken into account.

The assessment of the required room for the rivers focuses not only on the scientific evaluation of alternatives, but also reveals how room for the river can be ensured including public awareness raising, institutional and legal matters.

These aspects will be dealt with in three pilot studies, in which the investigations will focus on the possibilities and problems of the implementation of the proposed measures at a local level. In these pilot studies close co-operation will be sought with local authorities and stakeholders, such as water boards, municipalities and inhabitants.

The results of the project will be published in a number of scientific journals.