Die Grundwasseranreicherung (Dotation) der Lobau

1990

S. 23-28

4 Abb.

Unselbständiges Werk

200057939

The funktion of the Lobau area as a natural recreation area and as a ground- water reservoir has been impaired since the correction of the Danube put an end to extensive flooding, since the ground-water level in the Marchfeld region northeast of the river has been sinking, since drinking water is being withdrawn, and since the river-bed has been deepening. The Lobau was proclaimed a water preserve and, in 1978, a nature preserve, too. This region situated downstream shall become part of a future national park to be composed of the riparian areas of the Danube and March rivers. Now the ground-water in the Lobau shall be enriched via the system of old arms of the Danube with Danube bank filtrate to be taken from the New Danube. Implementation of this project will begin with a natural test, the initial quantity of water totalling 500 litres per second. However, this dotation project can be fully workable only of the Danube hydropower plant Vienna- Freudenau is built. Only then there will be enough water available in the damming positions of the New Danube. The water will flow from the upper part of the New Danube-via a transition facility yet to be built and to be equipped with regulating installations - into the Old Danube. From there it will flow on into the upper mill-dam water and through two already extent weirs into old arms of the river of which some will have to be re-activated. From the lower part of the New Danube dotation water will flow on a stretch about 3 kilometres (1.9 miles) long through several old branches into the so- called Oberleitner water. Finally, this dotation water will flow into a new damming position at the so-called Uferhaus (Riverside House) and from there into the water arms of the lower Lobau. If, after passing this flow stretch about 23 kilometres (13.3 miles) long and after losses as a result of seepage and evaporation, there still is dotation water left, it will flow back into the Danube. Forecast examinations concerning the hydrological and ecological components of this dotation project have already been carried out and programmes elaborated in accordance with these findings. The water level will have to be raised only very slowly so that the biocenoses can adjust themselves to the new environmental conditions.