The Scheldt

Since the last ice age, about 10.000 years ago drainage from large parts of North-western France and Flanders to the north has been along the Scheldt River. The 'primordial valley' of the Scheldt coincided south of Antwerp with today’s Scheldt valley. The river flowed along present-day Antwerp towards the Brabant wall, then through current Krammer-Volkerak and emptied into the Meuse at Maassluis. The wall of Rilland, a north-south situated deck sand ridge in Zeeuws-Vlaanderen, prevented a more western runoff. From the Early Atlantic, about 8,000 years ago, the influence of the North Sea increased. A few sea arms penetrated the marsh and cover sand landscape of the low country’s from the west at that time. About 6000 years ago, an estuary near Tholen contacted the Scheldt valley. The Scheldt then followed a more westerly course at the site of today's Eastern Scheldt (Antrop & van der Reest, 2001).

Between 300 and 700 AD, the full area of current Zeeland flooded, mostly out of low-lying peat. The Scheldt estuary acted as a burglary channel. The peat was knocked out in many places and mudflats were deposited instead. During the Dunkirk Ill transgression in the 9th century two more burglary channels would be formed. One was formed south of the then Scheldt estuary, the Honte and even further west the Sincfal, later the Zwin, was formed. The Sincfal would form a natural border between the Frisians and Flanders. At that time, the Honte was nothing more than a creek. During the 13th century it would come into contact with the Sincfal and the Scheldt, since this change the Scheldt water runsoff westward via the Western Scheld (Antrop & van der Reest, 2001).

The first use of the Western Scheldt dates between 35 and 70 thousand years; fishing and bridge building were common around this time. This is known due to archaeological finds. The first mentions of the Western Scheldt in writings date from the Romans called Plinius, Tactius and Ceasar. In this period, the Scheldt was deep. During the roman period, the Scheldt was slowly cultivated, resulting in rapid modernization of the area. Stone building, castles and rapid urbanization became common in the area. Many of today’s ferries still use the same location as their Roman predecessors (Bureau Voorlichting, 1993).

To protect themselves from floods, inhabitants of the Scheldt region from the 9th century onwards Vliedbergen and built individual dikes that were not closed. From the 10th century onwards, the inhabitants started collectively and often under encouragement of the lord of the abbeys with the construction of ring dikes. In a period of about 50 years (between 1200 and 1250) large parts of Walcheren, Zuid-Beveland and Zeeuwsch -Vlaanderen were provided with enclosed ring dikes (Antrop & van der Reest, 2001).

The Scheldt River is a freshwater river with some saltwater influences coming from the North Sea and the Western Scheldt. With the tidal influence of the North Sea the Western Scheldt is brackish and the Scheldt river can also become brackish depending on this tidal influence of the North Sea/Western Scheldt, the seasons and other weather events.

Fish species frequently found in the Western Scheldt and Scheldt river delta are cod, flounder, whiting, anchovy and dab. Also shrimps, crabs, mussels an oysters are found here. The Western Scheldt is an important migration route for migratory fish that swim from fresh water to salt water and vice versa. Some fish, for example the sea and river lamprey, twaite shad, and anchovy, have a special protection status (Wageningen University & Research, 2007).

The salinity of the Western Scheldt and the Scheldt plays a key role for the water quality. Salinity affects the oxygen concentration in water. Salinity also has an effect on the way marine animals and plants take up heavy metals and other chemicals from the water. The fluctuation of salinity in the area makes the area see different species in different areas and this changes throughout the seasons. The species that prefer fresh water will move more land inwards towards Antwerp and beyond and the saltwater species will move more towards the North Sea (Life-sparc, 2022). Recently, the RIVM has announced a statement saying no fish are to be allowed to be eaten that has been fished from the Western Scheldt, because of the increased amount of PFAS in the Western Scheldt. This is since PFAS is linked to serious health risks such as cancer (PZC, 2022).

The current functions of the Western Scheldt can be described as hosting shipping and industry on the shores, outflow of waste and cold water inflow, recreation, nature, fishery and mineral extraction. All these functions may not always operate in harmony with each other. Shipping is a major component of the Western Scheldt, the maintenance and growth of the industry dependent on dredging in the Western Scheldt to enable large-capacity ships to reach Terneuzen and Antwerp. Dredging also has a negative impact on the nature and flow of the Western Scheldt. In 1930, the Western Scheldt was dredged by half a million cubic meters a year; by 1985 it was 12 million. In the harbors 2 up to 5 cubic meters of sediment must be dredged every year (Bureau Voorlichting, 1993).

Besides its use as an important shipping route, the Scheldt also has many other functions, such as the disposal of sewage and wastewater and the supply of cooling water, recreation, nature, fishing and mineral extraction. These uses are often difficult to coordinate. Policy plans provide the guidelines to balance these functions according to needs and uses (Bureau Voorlichting, 1993).

The brick industry became a major industry between the 19th and 20th centuries. Annual floods in the upper area of the Scheldt River allowed rich sediment to be trapped. This facilitated this form of exploitation of river resources. The deposition of these alluvial clays was not only a natural occurrence, human interventions increased its effect. Deforestation increased the river’s water discharge causing more erosion. This resulted in more overflow along the river banks, increasing the deposition of the sendiment (van Strydonck & de Mulder, 2000).

Clay from the Scheldt can be traced back to products from the 14th century, indicating a history of use of this natural resource. Clay from the Scheldt is most famous for its use in Scheldt stone, known as a porous stone with low compressive strength but high durability. The harvesting and production of Scheldt stone would usually take place in the upper reaches of the Scheldt. This is the case because in the lower Scheldt, the clay and sediment would contain too many organic substances that would significantly reduce its quality. However, the Scheldt stone would fall out of favour in recent decades (van Strydonck & de Mulder, 2000).

The culture of the Scheldt was formed around the use of the river. After settling along the river inhabitants attempted to prevent floodings. Reducing those risks required interventions that changed the landscape. The resources provided by the river, along with its important access to the sea, made it an economic boost for the area around it. However, the floods also submerged many towns and villages, resulting in a diverse landscape of industry, cities, large green spaces and wetland. All these factors have played a key factor in forming the local culture and still do.

The need to contain the river and keep it open for trade requires a lot of political effort between countries but also on the local level. In modern times, we have seen this happen with the depoldering of the Hertogin Hedwigepolder. The depoldering of the Hertogin Hedwigepolder was the result of an agreement between the Netherlands and Flanders as part of nature development. Depoldering is regulated in the same treaty as deepening of the Western Scheldt. The discussion on depoldering shifted to an identity-undermining conflict, because locals in the Netherlands did not want to cede land to the sea, but for the Flemish side it was a necessity to allow the dredging of the Scheldt to continue. Politically, other solutions were sought to meet nature restoration goals and to prevent depoldering. However, this did not result in alternatives. Depoldering of the Hedwigepolder encountered strong opposition in Zeeland. Zeelanders have a great enemy in the sea that binds them together and from to which they derive their Zeeland identity. Many families in Zeeland know people who have experienced the disaster of 1953 (Kole, 2013). Cases like this highlight how different areas along the Scheldt have been shaped by life along the river and how their cultural identity is formed around it.

Antwerp and much of Flanders prospered after the Viking age due to the access to the sea and rich agriculture land. During the Western Scheldt, access was not yet an issue and floods only affected the lower lying farmland in the estuary. These floods were countered by creating flee hills where farmers could flee with their lifestock in case of flooding. However, this did not prove effective enough. Monks were the first to adapt the landscape with the construction of dikes. Human interventions such as salt winning caused the land subside, widening the river and putting more pressure on the dykes, which often broke due to the poor construction techniques used during this period (Bureau Voorlichting, 1993).

Over the centuries, the Scheldt became tamed and forced in formation according to human needs. This has had an undeniable impact on the ecological and morphological formation of the area. While ecological shifts can be rapid and very sudden, morphological shifts are gradual and often spanning years. Drastic and harsh measures such as dike construction, watermills or straightening parts of the river caused sudden and substantial changes for the local fauna along the river (van Strydonck & de Mulder, 2000).

These effects were the most visible for migratory fish, with the exception for brown trout and burbot; all other species that disappeared were migratory. The loss of these species was mainly caused by industrial overfishing during the 19th century. Besides overfishing, obstructions in the Scheldt made the migration of these species more difficult. The interventions in the river also made the mating grounds less accessible, further reducing the population. Waterworks the Scheldt also had a negative impact on the bird population, as the construction of dikes and canalization of the river meant a loss of regularly flooded wetlands (van Strydonck & de Mulder, 2000).

The most obviously affected population was the plant community. Periodic floodings before the human interventions spread along the river banks, creating all kinds of plant communities. Riparian forests, marsh vegetation and freshwater marshes largely disappeared along the Scheldt. The lower Scheldt in particular is unique for its salt and freshwater influences, depending on the tide. These are unique biotopes on a European scale (van Strydonck & de Mulder, 2000).

During the days of today there are not many differences from long time ago, most activity done by the humans are dredging and replacing of nourishments meaning maintenance of the dikes. The only difference would be that it dredges sand instead of peat and the main goal is use the sand for construction materials or either replacing the eroded sand of the dikes and dunes. In addition, the Depth of the Scheldt is deeper and deeper within the years to come due to the increase of the ship sizes therefore the new legislation is trying to maintain the depth at -13 m NAP.

The main problem of dredging is that it does not only affect the seabed or riverbed, but it also does affect sea life. Within the dredging activities, bacterial colonies might be affected, so the whole food chain of sea life is affected, making the water's quality worse. This will result in a reduction of fish and even vegetation. In addition, in some cases it can also poison the soil and will destroy even more the vegetation and sea life.