Water systems and risk analysis

Abstract

Worldwide the water management sector is about to review the design standards for water systems, as expected climate changes may possibly increase the frequency of flood events. This paper reviews new flood standards for surface water systems in The Netherlands, also presenting a cost-benefit analysis. Flood standards were formulated after several serious incidents in 1998 and 2001 to inform residents about the level of protection that they may expect to receive. At this moment all water boards are about to evaluate their water systems using these standards. The cost-benefit approach has been applied to determine whether the necessary measures to comply with such standards were cost-effective. We found that the standards make too much a simplification of the variety of water systems, and lead to costly measures without being beneficial while many small-scale floods in The Netherlands do not cause any significant damage. A better starting point to anticipate on climate change is to prevent damage, instead of the prevention of flooding.