2021

Interview Bert Rousseau (water-link) regarding the impact of the high-water levels in Belgium

The heavy weather events of July 2021 also had major consequences in Belgium. The province of Liège (Luik) was particularly affected. At that time, there was concern about the lock near Liège, where the Meuse and the Albert Canal come together. The drinking water company water-link extracts water from the Albert Canal to produce drinking water. In what way was water-link confronted with the high-water crisis of 2021?

The Albert Canal provides 40 per cent of the drinking water supply to Flanders. The canal is entirely supplied by the Meuse. This also applies to the Nete (Nèthe) Canal, a side branch of the Albert Canal.

Flanders is highly dependent on the Meuse. Not only for drinking water production, but also for various economic activities, such as businesses and shipping. The Albert Canal is in fact a major industrial axis along which major companies are situated. The water in the Albert Canal runs on into the Port of Antwerp.

In this location, around the port, freshwater mixes with the salt water in the Scheldt. Flanders is confronted with the problem of disturbed silt, particularly during dry periods when there is too little freshwater. To keep an eye on matters, drinking water company water-link measures the conductivity. This will be further elaborated in later sections of this report.

Water from the Albert Canal

Process technologist Bert Rousseau from water-link tells us about the impact of the high water in 2021. Bert is responsible for the monitoring of the raw water source from the Meuse, the Albert Canal, and the Kempen canals.

"We had learned from reports that the Meuse was likely to overflow its banks. We monitored the flow rates of the Meuse and saw that they were rising to previously unrecorded levels. Normally, the average flow of water via the Meuse is 250 cubic metres per second. On 15 and 16 July, the flow rate of the Meuse increased to 3,000 m3 per second. In the past, we have sometimes measured flows between 1,000 and 2,000 m3 per second, but never above 3,000 m3 per second, and certainly never in the summer. It was indeed highly exceptional.

Despite these events, the Albert Canal itself maintained a slowly flowing water course. This is because high flow rates are not permitted – as these would cause the dikes to collapse. At that time, it was feared that the lock at Liège might collapse. It was under high pressure during the flood. Fortunately for the shipping sector, the lock held up."

Canal system

To provide Flanders with water, seven canals were constructed between 1827 and 1947: known as the Kempen Canals. Of all the Belgian canals, the Albert Canal is the most important, because it connects Liège and Antwerp. The canals are artificial watercourses. As Bert further elaborates: "The natural watercourses in which the rainwater ends up are separate from this canal system. The only supply the canal system has are the locks at Liège – otherwise, very little water comes in. This means that there are never major changes in the flow rate of the Albert Canal, not even during extreme rainfall.”

Measurement during the high-water peak

Coincidence or not: the day that the flow rate in the Meuse reached its highest peak was also the day that Bert had planned to do sampling, from both the Albert Canal and the Meuse. "At that time, we took samples from the turbulent Meuse water that was rushing past. From these samples, besides the suspended matter content, we also determined pesticides and nutrients.

In the Meuse, the suspended matter content was very high, because everything was being churned up. As soon as the Meuse water came into the Albert Canal, it calmed down. The flow rate reduced, the water flowed more slowly, and the suspended matter settled. This happened mainly at the start of the Albert Canal.

At our abstraction point a little further along, all the suspended matter had already settled. We continued to monitor to see whether any extra contaminants would appear. After all, we didn't know what the effect of extra water running off the fields and from wastewater treatment plants would be. But after the analyses, it emerged that the dilution effect of the enormous mass of water ensured that we had no problems with contaminants."

Dilution effect

The question that arises is: how extreme was the dilution? "To determine that, we measure the conductivity. In normal periods, the conductivity of the water we abstract from the Albert Canal is between 400 and 500 µS/cm. In 2021, due to the wet summer, the conductivity reached a maximum of 556 µS/cm. The water that we abstracted that originated from the high water measured 339 µS/cm.

As a comparison: in dry periods, the measurement values here can rise to above 800 µS/cm (the maximum value at the end of the drought in 2020 was 838 µS/cm and in 2019 865 µS/cm)."

"Never previously so clean"

What were the consequences of this dilution? "For us, the high flow rate turned out positively. To be honest, the Meuse water has never previously arrived at us so clean. Our experience therefore differs from that of our colleagues in the Netherlands and Brussels, because they abstract directly from the Meuse. Our colleagues had to shut off the water abstraction due to the turbidity of the Meuse. Our situation is different because we use the Meuse water from the Albert Canal."

Climate-proof drinking water

The high water in 2021 is an illustration of extreme weather events that can occur as a result of climate change. In preceding years, water-link was confronted with extreme drought. In 2019 therefore, a plan was initiated to make it possible to cope with the consequences of extreme weather in the future. At that time, different options were put forward to provide for a climate-proof drinking water supply. Some examples: desalination at the Oelegem site; reuse of effluent from the Antwerp sewage treatment plant (STP) as process water for industry; construction of an extra storage basin; and the linking of the water networks of water-link with those of groundwater company Pidpa.

Implementation of master plan

Where are we now with the implementation of these measures? Bert: "With the measures included the plan, we must be better prepared for extremely dry periods. We expect extreme drought to occur more often. At this point, some of the projects mentioned above have already been completed; others are still under way. Current state of affairs?

The linking of the water-link and Pidpa water networks is finished, so that we can intervene for each other in emergency; the project for the reuse of the effluent from the Antwerp STPis still underway, but there have already been pilot tests in the port of Antwerp; we’ve also looked at the use of a desalination plant, but we’re currently reserving this option as a backup measure; the project for an extra storage basin in Oelegem, to increase the reserves, is still in full throttle This is happening in collaboration with the government of Flanders."

Everything is about water availability

"Another example of a climate measure comes from Vlaamse Waterweg (Flemmish Waterway), the operator of the Albert Canal. Pumps are being installed at each lock, so every time the locks operate, the water can be pumped back up. This means the water availability in the canal is more reliable.

Moreover, the government of Flanders has been busy on a reactive consideration framework. Different experts have mapped out the impact of various water-saving measures and have provided the Flemish government with a toolbox based on their findings. This is the 'Reactive Consideration Framework.' When severe drought arises and the Albert Canal comes under significant pressure, the government can impose highly targeted measures, while having insight into the consequences of the measures. It goes without saying that restricting the abstraction for drinking water production will only be done as a last resort, given the major social impact it could carry."