It was a crisis, in recent days at many water boards. A lot of rain had fallen in recent weeks and from last Thursday there was suddenly so much wetness, sometimes as much as fifty millimeters in one day, that especially smaller and medium-sized rivers could no longer process the water properly. Floodplains filled up, stream valleys were flooded. There was no serious flooding with major damage.
The Rivierenland Water Board in Tiel probably received the most work of all 21 water boards in the Netherlands. The water managers there had their hands full with the Linge; they eventually managed to limit the nuisance caused by this river, the longest river in the Netherlands at over a hundred kilometres, to flooded basements and gardens in Leerdam and Geldermalsen.
With pumps, pumping stations and water diversions, the water board managed to retain the large amount of water that ended up in the Linge via full ditches in the area as much as possible, so that not all water from the Linge would drain into the Merwede Canal, and thus at Arkel and Gorinchem might walk on the quays.
“We used the Linge as a buffer zone,” said the spokesman for the water board. It was especially exciting whether a number of houses located outside the dike in Leerdam and a parking garage in Geldermalsen could be saved from major damage. That worked.
Increasingly extreme rain
It has once again become apparent that although the Netherlands does endure a fixed amount of water every year on average, all this rain increasingly falls in extreme form, in short periods. “We have to constantly adapt. We may soon have a very dry spring again,” said a spokesman for the Union of Water Boards.
There was no nuisance at the major rivers; the flood wave in both the Rhine and the Meuse has remained well below the maximum capacity of both rivers and will not come close to that in the coming days. By way of comparison: 1,400 cubic meters of water per second will enter the country via the Meuse, compared to 3,500 cubic meters per second during the disaster in Limburg a year and a half ago.
“There really isn’t much going on. We have sufficient space on our main water system,” says water expert Vincent Beijk of Rijkswaterstaat. However, two storm barriers were closed last Sunday: the Hollandsche IJssel barrier in Krimpen aan den IJssel, due to the high water levels, and the inflatable Ramspol barrier near Kampen. The latter was closed due to a combination of wind gusts and precipitation. Moreover, a lot of water had already been discharged into the IJsselmeer, which could not easily be discharged to the Wadden Sea.
January is on average the month in which the highest high water waves flow through the Maas and Rhine. Raised water levels usually follow in the spring when the snow melts in the mountains. “But usually that melting is gradual,” says Beijk. With all the rain you would expect that the groundwater levels have finally returned to the desired level, after the long summer droughts of the past five years.
High water wave
Yet that is only partly true, according to the Vechtstream water board in Overijssel. The abundant rain has indeed replenished the groundwater supply. “But so much rain has fallen in a short time, rain on rain, that we can’t just hold all that water. You would like the rain to fall more gradually, so that it sinks nicely into the soil. We really need more rain in the near future,” said a spokesperson.
The water boards are not very concerned for the coming days, although a ‘high water wave’ from the Rhine and Maas still requires attention, according to a spokesman for the Rivierenland water board. “When the water in the rivers gets high, we get seepage; water that flows into the polders under the dikes. We have to pay attention to that.”
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