Benefit of starting early

Abstract

To fulfil the new safety standards of the Netherlands against flooding in the future, a great deal of work needs to be performed to prepare the flood defences system, at a quicker pace than is currently achieved. For this reason the HWBP is researching methods which can improve the efficiency of dike reinforcement projects. This thesis was initiated to analyse what could be done in the transition period between registration of a dike reinforcement project at the HWBP programme and the start of the reconnaissance phase of the project, as it is potentially useful to utilize this time period. This thesis focuses on the impact of implementing monitoring and soil investigation earlier was analysed, because information collected before or during the transition period can be used for the benefit of the dike reinforcement projects. For this a theoretical case of the dike trajectory at Amerongen was used, for which piping is the dominant failure mechanism. The benefit in performing additional soil investigation and monitoring is dependent on the project phase in which the measurements are started and/or performed. The aim of this research was determine when the methods need to be implemented, how much investment is needed and what the expected benefit of the measures is. The benefit can be expressed in expected project costs in case of stronger parameters are found and in expected annual risk if weaker parameters are found. For the applied case dike trajectory at Amerongen the expected reduction in project costs is 19,4% of the initially estimated project costs if the measurements were performed or started early. In comparison, the expected project cost reduction for the common project structure is 13,3%. The investment costs due to monitoring and soil investigation was 4,6% of the estimated project cost when starting early and 4,1% for the common project structure. In conclusion, by investing 0,5% of the estimated project costs on starting monitoring and soil investigation early in the dike reinforcement project a 6,1% reduction in the project costs is expected.