Delta Life 7

DELTARES, MARCH 2017 21 focus on the effects of flooding, such as the number of potential victims and economic damage. Always basic protection and sometimes a little extra The new standards require the same basic level of protection everywhere behind the Dutch dikes and dunes: a probability of no more than 1 in 100,000 annually that a person can die due to flooding. Where there may be extensive damage or numerous casualties, or in places where the infrastructure is vulnerable, the protection standards have been made more stringent. We don't want large areas to be deprived of electricity or hospital services. So government is investing more in the dikes protecting these areas. On the other hand, we can save money, for example in areas where there are few people or where there are not many valuable or vulnerable buildings. It should be pointed out that the basic level of protection is in place in all these locations. Tackling large calculations with new tools Dike management authorities report to the Minister on the condition of the dikes every twelve years. We have learnt an enormous amount about strengths, loads and uncertainties and so the basis for the approach will involve large calculations. To ensure that everyone works with the same knowledge and methods, a new tool has been developed: the Statutory Assessment Instrument (WBI). Local knowledge is required for each specific section of dike and that knowledge can often be obtained only from the managers themselves. It is combined with specialist knowledge, which the WBI makes accessible to managers and engineering firms with special software. Most management authorities participated in a full rehearsal with the instrument in the autumn of 2016. This involved practising with the WBI to produce a safety assessment. Some technical areas did require fine-tuning but everyone was happy with the collaborative approach. This year will be devoted largely to collecting information and ongoing improvements to the instrument. All flood defences are required to comply with the new safety standards by 2050.