An Integrated Approach to Flood Risk Management Management and Spatial Quality Enhancement for a Netherlands’ River Polder Area

Abstract

In the previous paper, the aspect of including interventions from different flood risk safety layers is explained quite concisely. In this publication, an extended approach for the inclusion of interventions from different flood risk layers are described in more detail.

The paper demonstrates how the Netherlands’ policy shift from a probability-based flood risk target to a risk-based flood risk target increased the range of interchangeable measures for flood risk protection. Though applying a risk-based mindset, the Netherlands’ flood risk reduction targets were, until recently, defined as probability-based safety standards. This resulted in a uniform dike-ring approach in which different dike-rings have different safety standards, based on, amongst others, the perceived economic value of the area, which are applied uniformly to the whole dike-ring. Within this probability reduction based system it is possible to define interchangeable flood risk management interventions at different locations, for instance, by proposing interventions of different scales, as demonstrated in the previous publication. The ‘Room for the River’ project is an example of providing alternative probability reduction measures, since both dike elevation and load reduction reduce the probability of a flood.

However, applying risk-based flood risk targets conceptually considerably extends the amount of interchangeable flood risk measures. Not only does it, next to probability reduction measures, allow for the inclusion of consequence reduction measures (such as flood proofing buildings, elevating areas, and improving evacuation), but compared to the uniform dike-ring approach, it also allows for differentiations in probability standards per dike segment. This conceptually more fine-meshed perspective of the dike-ring extends the amount of variable locations for flood risk management interventions.

In the research-by-design study described in this paper, the examined method for the aspect of ‘changing the layer of the flood risk intervention’ is applied to the Albasserwaard case study area. The paper demonstrates how the Netherlands’ recent shift from a probability standard target towards a risk-based target, by increasing the amount of interchangeable flood risk management interventions for the case study area, strengthens the possibility of deploying the developed method and the use of spatial quality as an ex-ante criterion.