Floods

Austria, Czech Republic, Poland and Germany were all affected by severe flooding between July and August of 1997. It was the worst flooding seen in the Czech Republic for decades and consequently 46 people died due to drowning.

Such was the scale of the rainfall between the 5^th and the 9^th of July in 1997, that more than 225 landslides were activated in the region of Vsetín Czech Republic.

The rainfall totals according to the monthly weather report was between 450-600mm, which fell between the 5^th and the 9^th(see map). This reached totals of 400-500% of the long time average. This large scale rainfall has occured in the past in Moravia. In July of 1897, the heaviest European rainfall was recorded at 345mm in 24 hours. It occurred in the Jizerske Mountains on the 29^th of July, 1897, and subsequently caused the death of 180 people.

During the days of wide urban expansion in the industrial revolution, level land near rivers provided ideal sites for new factories and extensive uncontrolled development of flood plains took place. Flood defence measures have therefore been necessary to protect such buildings and since 1918 flood defence walls have been present along stretches of the Bečva.  The huge floods of July 1997, however, destroyed most of this defence (154950000 CZK of river defence damage, pers comm.: Hanslian, 1999) as the river pursued its own course, flooding wide areas irrespective of vertical objects.

Since 1997 intensive flood defence construction has occurred in the major towns of Vsetín, Valašské Meziříčí, and Rožnov p. R.. The river channel has been straightened and trees cut back from the water's edge and natural river banks replaced by walls of concrete (see Plates ).

Artificial waterfalls/ steps have also been built in the water channel to decrease the energy of the river and create sedimentation behind the rim of the steps (see Plate).

This helps to keep the river channel downstream deeper to hold a higher volume. The sediment is then periodically dug out.

This flood defence scheme is extremely expensive with building material brought from the whole district. This also has a great impact on the ecology with loss of important riverside vegetation and fauna such as the otter and kingfisher . The large steps built particularly affect fish, for example, stopping the migration of salmon upstream for their natural reproduction.

During the floods there was much speculation from scientists that harmful pathogens could be spread due to many animals being killed but the water quality actually improved due to the natural self-cleaning abilities of the river. After the floods the river bed was much wider and was regaining its natural state but since the flood defence it has been straightened thus increasing its speed and energy. This energy will be mostly concentrated downstream, after the confluence of the Bečva rivers, on the lowland areas such as Choryně and Hustopeče who have little or no defence and are liable to future heavy flooding.

Water companies such as Povodí Moravy are responsible for river protection but there is a problem as this law is in confusion with the law for nature protection and at the moment there is no harmonisation between these laws.

The PLA and nature conservationists Dvorský and Dvorská oppose this flood defence construction and feel the river should be left to find its own course as it will surely flood again irrespective of flood defence. The floods of 1997 were a great catastrophe and the result of 100 years water. The present flood defence is only capable of withstanding a flood event of 20 years water.