An Integrated Approach to Define Estuarine System Resilience, Applied to the Upper Sea Scheldt, Flanders, Belgium

Abstract

The Upper Sea Scheldt (Flanders, Belgium) is a part of the Scheldt estuary which extends from the North-Sea in the Netherlands to the shipping locks in Ghent with a total length of 160 km. Challenges on flood protection and nature development in this unique fresh water estuarine system are addressed in the Sigma-plan. Cumulative effects of i) the autonomous morphological development of the estuary, ii) the further evolution as a consequence of past realignments and dredging works, and iii) sea level rise, result in an increase of tidal dynamics and turbidity which affect both habitat and light climate, and finally disrupt the ecosystem functions. In order to better understand the system functioning and to prepare for counteracting these undesired evolutions De Vlaamse Waterweg, the waterway manager, has launched a study programme to investigate solutions and to prepare a vision for the future management of the river. An extensive modelling instrument was developed coupling different state of the art modules into one model chain. The developed instrument proved to be highly effective to study (i) the interdependencies between the different river functions which allowed for an integrated analysis and evaluation of potential measures, and (ii) the robustness of the measures for climate change, and allowing the selection of a set of measures providing a desired level of system resilience. As such the results of the study form the backbone for the development of a future vision on estuary management, while the model instrument will continue to be used to study design alternatives and finetune measures for implementation.