Flooding threat as experts examine dike

28 January 2004

AMSTERDAM — Inspectors began work on Wednesday morning to determine the cause of a mystery dike subsidence, but the situation remained serious as 543 evacuated residents of the southern Limburg city of Stein waited to be allowed to return home.

The water level in the Julianakanaal has been lowered by about 1.2m, allowing experts from the Department of Public Works and Water Management to examine the dike. Inspections started at about 8am on Wednesday.

But the department also said the subsidence of the dike — which is “seriously undermined” — remained a mystery. The dike was last inspected on Tuesday morning, but no problems or areas of concern had been detected.

The fire brigade said there was still a chance the dike might break, posing a risk of 2m flooding to the town of Stein, near Maastricht. The marshy region behind the dike is about 6m lower than the normal water level in the canal.

Stein Mayor Ed Meijer announced on Wednesday morning that residents were not yet allowed to return to their homes. The residents were evacuated on Tuesday afternoon because their houses were at immediate threat from the possible flooding.

The mayor had said on Tuesday night that it could be several days before residents would be allowed home. He said the condition of the dike — about 10m of which has subsided — remained “alarming”.

Police are patrolling Stein to prevent the arrival of “disaster tourists” and to thwart possible burglaries after the mayor announced an emergency decree at about 4.30pm on Tuesday. He also requested residents to await news of possible threats by checking teletext on L1, a type of disaster broadcaster.

Meanwhile, the water management officials are also inspecting other parts of the dike and it is possible that divers will be called in. Department staff and the fire brigade worked throughout the night to strengthen the dike with large sandbags, each containing about a cubic metre of sand. The sandbags were delivered by truck.

A pedestrian saw the subsided stretch of dike on Tuesday afternoon. With water trickling out of the canal, the passer-by alerted authorities, resulting in the cancellation of all shipping on the canal and the evacuation of threatened residents.

The locks in the Maastricht suburb of Limmel and at Born were closed, allowing a slow fall in the canal’s water level. The water level is still falling, but only by a gradual 5cm per hour to prevent the dike from weakening further.

The Julianakanaal is an important shipping route through the province of Limburg and supplies coolant water to chemical concern DSM, which has a plant located several kilometres from Stein. But the company has emergency pumps and will only be hindered if the dike breaks.

Work on strengthening the dike will continue on Wednesday and the fire brigade said the job was not without its dangers because if a pontoon knocked against the dike, the situation could worsen, an NOS news report said.

Most evacuated residents were staying with relatives of family, but others have been given temporary shelter by the municipal council.

A dike expert with the Delft Technical University has said the dike subsidence could be the result of the drying out of the dike, which largely consists of clay. The dike wall might also have been too steep.

The collapse of a peat-based dike near the central town of Wilnis last year was blamed on extreme dry weather, which caused the peat to dry out and become too light. This caused the dike to tear and as water seeped into the dike, it collapsed under the added strain.

About 450 Wilnis residents were affected by the eventual flooding and the damage bill amounted to an estimated EUR 60 million.

Subject: Dutch news