For decades, the rigidly regulated Salzach has dug deeper and deeper into its canal-like bed. There was a threat of a rupture of the river bed, which would have massive repercussions, and there were problems with flood protection and natural plant and animal communities. Now the body of water is to be transformed into a livable natural area by widening the river.
The Upper Austrian environmental ombudsman has long advocated a free-flowing Salzach, and now things are moving in that direction. The hydraulic engineering administrations of Upper Austria – in particular the water district of Braunau -, Salzburg and Bavaria are implementing the rehabilitation. Due to the earlier straightening of the Salzach, this has deepened and partially lost contact with the foreland.
Positive development
The aim of the rehabilitation measures is not only to stabilize the bed, but also to give the Salzach back its original character to some extent. These include in particular gravel banks, side channels and more dynamics in the river and in the floodplain.
The first kilometers on the Upper Austrian side, below the Tittmoninger Bridge, were renovated under the so-called no-regret measures. “The bank protections were removed, the river widened and the resulting bed load cleared into the river. The first floods have also done a good job and redesigned the bed and the river bank,” said the environmental ombudsman. The hydraulic engineering administration has now applied for the continuation of the rehabilitation of the entire Lower Salzach in Salzburg, Upper Austria and parts of Bavaria: For this purpose, four dissolved bed ramps and eight alternating, dynamic widening sections over a total length of around 25 kilometers and six tributaries with a total length of around 13 kilometers are to be implemented will. The environmental ombudsman’s natural river variant had originally largely dispensed with transverse structures. “Even if the variant that has now been implemented is not the best from an ecological point of view, it is a significant improvement from a water management and ecological point of view and was positively assessed by us in the EIA procedure,” said the environmental ombudsman.
According to the environmental ombudsman, the measures already implemented to clean up the Salzach are bringing more sediment from the Upper and Middle Salzach to the Lower Salzach thanks to increased sediment continuity. “Investigations into the bed load morphology in the Tittmoning Basin indicate that stabilization of the Salzach bed between river kilometers 45 and 35 is possible in the long term simply by widening the water body.”
With the projected expansions and the creation of the tributaries one finds more or less sufficient.
Renaturation is therefore possible without the construction of transverse structures, which also saves a large part of the production costs. “This natural water remediation is therefore ecologically, but also economically a success.”
Source: Nachrichten
