The missing link in adaptive delta management

Abstract

Decision-makers in low-lying coastal zones are confronted with uncertain developments around flood risk.These drivers are surrounded by large uncertainties, which requires delta management to be adaptive. This research offers insights about adaptive delta management for the Rhine-Meuse estuary from three perspectives: a physical, a socio-political and a integrated perspective. In the physical perspective, the effect of pump capacity on the water system of the Rhine-Meuse estuary is quantified; one of the adaptation options against sea level rise. To assess the adaptation potential of pumps, the case study Delta21 is used; a plan to construct an artificial lake with an area of 35 km2 next to the Maasvlakte 2 in combination with a pump capacity of 10 000 m3/s. The Rhine-Meuse estuary is divided into four sub-areas depending on the
dominant hydrodynamic process: storm surge dominant area, flood storage dominant area, discharge dominant area and transition area. For each sub-area, the effects of Delta21 are computed on 1) water flows, 2) hydraulic loads and 3) failure probabilities. Delta21 succeeds in lowering the hydraulic loads and corresponding failure probabilities. At the same time, reductions are disproportionately over the Rhine-Meuse estuary leading to low reductions in some sub-areas. In the socio-political perspective, the focus is on decision-making and learning processes in management in delta management. The Rhine-Meuse estuary is characterized by a network structure, which means that knowledge and decisions do not belong to one single actor, but those decisions come about during interactions between various groups of actors. Not only the decisions need to be adaptive to cope with uncertain circumstances, but the learning process itself must also become adaptive. To achieve this aim, a conceptual mode is developed. Two case studies are used; the Delta Program and Knowledge Program Sea Level Rise. A longitudinal analysis of the Delta Program resulted in different narratives over time and various learning types. Subsequently, the Knowledge Program Sea Level Rise is analyzed with semi-structured interviews, process-tracing and the conceptual model. Observations and challenges are translated into a roadmap of learning activities. Moreover, the DEALTa learning handbook is developed, to support actors in designing learning activities. The physical and socio-political perspective are united in the integrated perspective. On the level of technical studies, insights are shared about the relation between both aspects and how the integration can be improved in the future.