Description of the project area
The Pielach originates in the northern foothills of the Alps, approx. 5 km northwest of Annaberg, at an altitude of about 800 m above sea level. The river then flows into the Danube near Melk at an altitude of 208 m above sea level. The total length of the Pielach is 67,5 km and it has a catchment area of 590 km².
In the lower reaches, the low water flow (MJNQT) is 1,82 m³/s, the mean water flow (MQ) is 6,46 m³/s and the 100-year flood event (HQ100) is 370 m³/s.
The project area extends from the Pielach’s estuary into the Danube upstream to the estuary of the Nattersbach at river kilometre 59,3 in the so-called “Pielachleiten region”.
The lower reaches from the mouth to the Danube up to Prinzersdorf shows natural and well-structured river stretches. Upstream, many sections of the Pielach were straightened and the riverbed was narrowed considerably. This resulted in the extensive loss of river-typical structures. The regulation of the river greatly increased the bedload transport capacity of the Pielach, which led to loss of the gravel bed. In addition, the Pielach is fragmented into sub-segments by continuity interruptions (obstacles for fish migration). Also in the upper reaches, there are still some continuity interruptions and there are some short river regulation measures.
The Pielach is currently in good to moderate hydromorphological condition.
Hot Spots & Highlights
Three nature reserves “Pielachmündung-Steinwand”, “Pielach-Ofenloch-Neubacher Au” and “Pielach-Mühlau” are located in the natural river sections in the lower reaches of the river. Up to Rabenstein an der Pielach the entire river stretch is part of the Natura 2000-FFH European protected area “Lower Austrian Alpine Foothills”. The Natura 2000 bird sanctuary “Pielachtal” extends from the mouth of the Danube to Hofstetten-Grünau.
The natural treasures of the Pielachtal include rare species such as the Kingfisher and the Huchen. One of the last self-reproducing populations of this impressive fish species, also called “Danube salmon”, can still be found in the Pielach today. A LIFE project has already been implemented to protect this habitat.
The Pielach Valley offers visitors a colourful range of natural, scenic and cultural experiences.
Need for action
The section of the Pielach from the Danube estuary to the Prinzersdorf estuary has a good ecological status according to the fish ecological assessment. Here, measures have to be implemented to ensure the good ecological status in the long term. The upstream water body shows only a moderate status. There are deficits in hydrology, continuity and morphology. Due to the lack of gravel islands and habitats that are characteristic for this river type, a type-specific fish stock cannot develop. In the upper reaches, the main priority is to restore the longitudinal continuity.
Numerous flood protection projects have already been implemented on the Pielach in recent years. Some are currently being implemented. But there is still a need for action in the middle section of the Pielach between Prinzersdorf and Obergrafendorf. Individual flood protection projects are currently being planned.
The aim of the GE-RM Pielach is to coordinate flood protection measures with the necessary measures to achieve good ecological status. The concerns of nature conservation (Natura 2000, nature reserves, bird protection), but also existing uses (e.g. water abstraction, tourism and recreational functions, fisheries) must be taken into account and measures with multiple benefits (so-called synergies) must be found.
Outlook and time plan
The River Development and Risk Management Concept (GE-RM) for the Pielach will be finalised by the end of 2021. This will be followed by detailed planning of pilot projects. The structural implementation of the pilot measures is planned for the second project phase of the IRIS-project starting in 2022.