Bart Schultz
Since the 2nd century BC, there have been three major periods of flooding in Belgium: Dunkirk I, II and III. During these periods, peatlands along the North Sea were covered with clay and sand. The Dunkirk II period took place in the 4th century and Dunkirk III A and B between the 10th and 12th centuries. The floods during the Dunkirk III A period created the Zwin as an inlet from the coast. To prevent the flooded area from expanding, the Blankenberge Dike was constructed from Bruges to Blankenberge. Later, a dike was constructed from Sint-Pieters-op-den-Dijk to Uitkerke.
After the floods during the Dunkirk II period, small-scale polders were constructed, which discharged excess water to the North Sea through discharge sluices at low tide. This resulted in a land level of up to five metres below the flood level.
In the floodable part of the Zwin area, various polders were constructed from the 13th to the 19th century. Most of these are mainly used for agriculture, but various nature reserves have also been developed.
Between Antwerp and Ghent, river polders were constructed in the tidal zone of the rivers, mainly opposite Antwerp on the western bank of the Scheldt. Because the port of Antwerp developed so much afterwards, ports and industrial estates were constructed in some of these polders, for which usually landfill was applied.
Parts of Antwerp are also located in polders. Part of the city is protected from flooding by a quay wall along the Scheldt. The Masterplan for Antwerp provides that this quay wall must be raised by ninety centimetres in the near future. The middle section of it will be made movable. This has already been done in several other cities, such as Cologne in Germany along the Rhine. In Lillo near Antwerp there is a polder museum, which focuses mainly on the history of the polders in the region.
Water Authorities are responsible for water management in the polders, just like in the Netherlands. Initially, there were also many small Water Authorities here. In the past decades, many mergers have taken place and considerably larger Water Authorities have emerged. The list of Water Authorities in Flanders in Wikipedia lists 53 Water Authorities. In addition, there are a number of Water Authorities in Wallonia. In Brussels, the responsibility for water management falls under the government service Brussels Environment.
In the Netherlands, after many mergers, the number of Water Authorities has now been reduced from more than three thousand to 21. Based on the European Water Framework Directive, the division into Water Authorities would preferably have to be based on sub-basins within a country. For the Netherlands, this would mean 19 Water Authorities. So we are almost there. Perhaps in Belgium, further mergers of Water Authorities will be established in the near future in connection with this.
Several Belgian Water Authorities and Provinces show on their websites maps of the polders on their territory. Several authors have also published clear maps of the polder areas. Some examples are included.
