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 thernnational policy against flooding has shown the risks of casualties and economic damage to be much greater thanrnanticipated and desired.This seemingly controversial statement is largely attributed to a creeping discrepancyrnbetween the existent set of design standards for dike strength used for dam assessment and reinforcement programsrnin The Netherlands, and a steady social and economic development.These standards, laid down in nationalrnlaw in 1996, are, to a large extent, based on insights from the years 1953–1960.The observed spatial variation inrnsafety standards is not in accordance with the intentions of the law as it hardly reflects the spatial distribution ofrneconomic interests of 'dike-ring-areas'.The societal risk of flooding (the probability of large numbers of casualties)rnin The Netherlands appears to be several orders of magnitude larger than the societal risk for the combinedrnknown external hazards (e.g.industrial hazards and plane crashes).A further increase in flood risks is expected duernto climate change (increased sea level rise and higher river peak discharges), approaching the same order of magnitudernas induced by further economic and social development.Technical solutions should no longer form the solernanswer to this increase.Neither is it only the responsibility of water policy makers to cope with it.Too much focusrnon reducing chances of dike breaches by technical means causes efficient solutions in spatial planning to be overlooked.rnSolutions here include risk and potential damage reduction and avoidance strategies, which can be implementedrnby both national and local authorities.The decrease in public acceptance of risks of flooding hasrncontributed to the need to regard such risks more as external risks than as natural hazards.Compared to other countriesrn(in Europe, and the USA and Japan), the safety level of dikes in The Netherlands is already much higher andrnattuned to the high vulnerability of the population in Netherlands, with its low-lying areas, dense population andrnlarge investments.Disaster response, however, is insufficiently well-prepared.