With the Sigma plan, Flanders is working on a buffer against rising sea levels and extreme weather conditions. Along the river Scheldt and its tributaries, flood control areas and depolderings offer the river more room. Through LIFE Sparc - Space for Adapting the River Scheldt to Climate Change (2017- 2022) - the European Union provides financial support for the further development of eight Sigma areas in the provinces of East Flanders and Antwerp. These are Vlassenbroek, Uiterdijk, Groot Schoor in Hamme, Wal-Zwijn, de Bunt, Klein Broek, Groot Broek and Groot Schoor in Hingene (fig.1-1). In these areas, space is created for new, authentic tidal nature or mud flats. Nature restoration is crucial in the fight against climate change. Investing in biodiversity not only benefits endangered species and our living environment. A resilient river with sufficient mud flats and marshes can protect the entire region against the effects of extreme weather conditions. With extensive research and monitoring programs such as OMES (Research Program Environmental Effects Sigma Plan), MONEOS (MONitoring Effects Development-Sketch: NL-BE research program for the ecological functioning of the Scheldt estuary) and the specific monitoring of nature development in the flood areas themselves (INBO) the results of the project are closely monitored. What effect do the construction of these flood control areas and depolderings have on biodiversity in the area and how is the water quality and water level of the Scheldt evolving? This report extracts information from the results of these monitoring programs in order to determine a baseline measurement for the LIFE Sparc project areas. The baseline measurement is defined as the last measured situation before the start of the Sigma works in the area. At the end of the project, this report is supplemented with the latest figures and insights based on these monitoring programs. In addition, eight specific measurement campaigns in the project area the Bunt will yield measurement results on water quality before and after passage through the project area. This will be used to determine the influence of the project on water quality. The former use of the project areas includes mainly agriculture (Uiterdijk, Groot Schoor Hamme and Groot Schoor Hingene), meadows, deserted farmland, Poplar plantations (Vlassenbroek, Wal-Zwijn, de Bunt) in nutrient-rich conditions. Protected habitats and important regional biotopes were present on a small part of the surface. These were almost exclusively relict alluvial forests (91E0, different subtypes) and wetlands (6430 and rbbhf). Relics of the old forest flora were found only very locally. Because of the existing habitat, very few tipical estuarine animals or plants are found. Marsh Warbler was the most common bird, it is a tipical bird living in the shrubs below poplar plantations. The fish population is very moderate: no significant water bodies were present, no predator fish was present, exotic species were found or there were hardly any fish. Only the northern creek in Wal–Zwijn (‘de Kille’) scored "excellent" for fish. Both in Vlassenbroek and in Wal-Zwijn the species composition pointed to direct contact with the estuary. Estuarine fish species swim in these areas in the summer when Scheldt water is let into the polders. As a result, these areas had a higher diversity than the others. No benthos samples were taken in the project areas since there is no tidal nature. Of each area a height map is made. Both the topography in the areas and the bathymetry of the river can change under the influence of the execution of the 8 projects, due to silting up and erosion. The areas that have a higher altitude will evolve faster to reed marshes and floodplane forests with mainly willow, while the lowest lying areas will change into mud flats. Within the river the variation in flow rate is lower during low tide than during high tide. During high tide, a clear period of higher flow rates is observed with maximum rates around 1 hour for high water. 5 The suspended matter content in the Sea Scheldt has been increasing since 2009 and is shifting upstream in the summer period. For T1 (in 2022) the treated parameters will be measured again and the impact of the project areas on biotic and abiotic conditions will be analysed.
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