La
Licorne
RIVER TRAINING
The flow in the River Maas is very
much at will of the weather conditions. Notably depression that are accompanied
by heavy and lasting showers make the stream swell fast and formidable. The
topography in the upper reaches of the river is such that rising water will
flood its narrow valleys. The downstream flat netherlands, however, are exposed
to widespread flooding. Therefore, as from about 1200 AD dikes have been put in
place. At first to protect towns, fortifications and country manors, and later
to prevent great parts of the interiors from flooding.
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In particular the lands around Heusden endured hardship in times of high water. To the north they had do with Rhine water flooding into the Maas plains. Simultaneously Maas water coming from the east would continue to build up in the area. To the south the yield of regional water inflows would accumulate, and last but not least from the west marine floods might come in. |
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For the protection of the Lands of Heusden embankments were raised and the entrance to the Minor Maas was closed in 1273. |
From around the same time dikes have
been put up elsewhere to be gradually extended and improved in ever lasting
efforts to protect people, lands, good and livestock. Starting from somewhere
near Cuijk the embankment along the Maas had been raised and continued
downstream to where it is linked with the coastal defense system. Whenever the
river swells to come out of its confines, the dike will curb the water to the
outer marches.
While the water is standing up
against the dike the latter gets more or less soaked. When it has to endure the
pressure for a long time it might start to leak. In that case the risk of dike
breakage becomes eminent and the waterboards will be particular alert to
prevent that to happen. For in case the situation really becomes critical they
will divert some of the flow to enter the polders in order to give counter pressure
on the inland side of the dike. This measure also helps to lower the flood
levels by spreading the water mass over a larger area. For this purpose certain
portions of the dikes were deliberately constructed with a low crest allowing
high water to spill over into the polders. In 1569 such an inlet was
constructed near Cuijk for controlled flooding of large portions of interior
land along the Maas. Consequently the affected flood plain up to the coastal
estuary remained uninhabited for a long time.
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Around the year 1900 the Maas was cut off from the Rhine and given a new course, near the alignment it once possessed as a minor branch. This major excavating job was carried out by hand labor and took ten years to complete. Care was taken to provide adequate profile for the reinstated river. By giving the Maas its own way out to the open sea the flood hazard from the Rhine was brought under control. |
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To the west the sea defense
progressed as well. However, the in-flow from southern reaches remained a
problem, because high levels in the Maas would prevent the tributaries from
discharging into the river. Therefore a canal was excavated for the
surroundings of 's-Hertogenbosch
diverting the water by gravity to the west. Additional pumping facilities were
installed.
Other measures for controlling
floods concerned straightening the river course by cutting off meanders, and
clearing obstacles such as rising vegetation. However the thus faster flowing
river would score its sides and start meandering again. For this, numerous
jetties have been constructed to train the stream into its confines.
All together this made it possible
to start closing the spillways and to make the plains free from flood year-round.
Nevertheless, withstanding all efforts numerous breaches have occurred, and
were repaired. In such a country the fight against water has to be taken
seriously. Heavy floods as recently as in 1994 and 1995 have shaken up the
ignorant authorities once more. However, as recent as in 2005 new alams were
issued, also on account of the rise in the sea-level.