Dutch dikes, and risk hikes – A thematic policy evaluation ofrisks of flooding in The Netherlands

摘要

Dams in The Netherlands have never been stronger, yet the first country-wide assessment of thenational policy against flooding has shown the risks of casualties and economic damage to be much greater thananticipated and desired.This seemingly controversial statement is largely attributed to a creeping discrepancybetween the existent set of design standards for dike strength used for dam assessment and reinforcement programsin The Netherlands, and a steady social and economic development.These standards, laid down in nationallaw in 1996, are, to a large extent, based on insights from the years 1953–1960.The observed spatial variation insafety standards is not in accordance with the intentions of the law as it hardly reflects the spatial distribution ofeconomic interests of 'dike-ring-areas'.The societal risk of flooding (the probability of large numbers of casualties)in The Netherlands appears to be several orders of magnitude larger than the societal risk for the combinedknown external hazards (e.g.industrial hazards and plane crashes).A further increase in flood risks is expected dueto climate change (increased sea level rise and higher river peak discharges), approaching the same order of magnitudeas induced by further economic and social development.Technical solutions should no longer form the soleanswer to this increase.Neither is it only the responsibility of water policy makers to cope with it.Too much focuson reducing chances of dike breaches by technical means causes efficient solutions in spatial planning to be overlooked.Solutions here include risk and potential damage reduction and avoidance strategies, which can be implementedby both national and local authorities.The decrease in public acceptance of risks of flooding hascontributed to the need to regard such risks more as external risks than as natural hazards.Compared to other countries(in Europe, and the USA and Japan), the safety level of dikes in The Netherlands is already much higher andattuned to the high vulnerability of the population in Netherlands, with its low-lying areas, dense population andlarge investments.Disaster response, however, is insufficiently well-prepared.