ABSTRACT
In Asia and Europe floods are the most common natural disaster and in terms of economic damage, the most costly ones (Cred, 2008). Although the projected impacts may be marginal increases on the already large flood losses, climate change will probably have a major impact on the way in which we deal with flooding in the longer term. This especially holds true for urbanized areas in deltaic regions. Countless studies show that we should start now to adapt to climate change, to prevent costly emergency interventions in the future. This means that flood risk management strategies must meet present needs, while providing an adjustment path for the future (Pahl-Wostl, 2006; Ashley et al., 2007; Miller, 2007). For example, if governments were to take no action the UK population at risk will increase from 1.6 to 3.6 million and the cost for flood defences will increase from 3.9 to 48 million GBP by 2080 (Foresight, 2005). In developing countries the projected impacts are even worse. Particularly vulnerable are the rapid expanding mega-cities in these regions. With more than 90% of its population living in urban areas, Japan and The Netherlands are two of the most urbanized countries on earth. Urbanization and climate change are generally recognized as the major pressures inducing or intensifying floods and their impacts. Worldwide the challenge to address low probability-high impact flood risk and to reduce urban flood vulnerability has however, only recently received serious attention. This is likely because in traditional flood management approach responses to mitigate urban flood risks have been often set outside the realm of the urban system (e.g. where confined at catchment level) and responses at city level if any were predominantly passive using robust solutions such as urban defences and increasing the capacity of major culverts (Zevenbergen, 2008). In Japan, however, due to the regular occurrence of major flood events disaster relief and compensation mechanisms, damage mitigation measures specifically for urban areas have been implemented some decades ago. Transition and developing countries could learn from the lessons of Japan and from other developed countries, such as The Netherlands, which have already made the transition from agricultural to industrial, service-based economies. The first group is not yet stuck on past investments and, consequently, has greater freedom of movement.
