Water-safety strategies and local-scale spatial quality

Abstract

Delta regions throughout the world are subject to increasing flood risks. For protection, regional water-safety strategies are being developed. Local-scale spatial qualities should be included in their evaluation. An experimental methodology has been developed for this purpose. This paper concentrates on water safety in The Netherlands. The Deltaprogram aims to ensure the country's water safety until 2100. A sub-programme, Rhine Estuary–Drechtsteden, defines scenarios for water-safety interventions that use combinations of permanent or flexible, opening or closing of connections between the Dutch delta, North Sea and river systems. Cross-sections show water levels throughout the urbanised Rhine Estuary region, based on forecasts for each of the scenarios, and local-scale interventions, such as dykes or flood barriers. The interventions are rated using existing and new criteria for the evaluation of spatial quality. Dominant criteria for each area have been used to define design criteria. The choice of a solution on a regional scale is shown to have a significant impact on the spatial quality on a local scale. In particular, water-safety interventions that result in extreme water levels have a negative impact. The methodology is suitable for estimating the impact of a regional water-safety strategy on a local scale and provides valuable design criteria.