Lower Traun

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Lower Traun

Factsheet: Lower Traun

Country AT
River Name Traun
Site Name Lower Traun
River Characterisation
River typology
Location (Lat Lon) 48.1150011009253, 13.9601254463196
Altitude mid-altitude: 200 - 800 m
Catchment area large: > 1000 - 10000 km2
Geology Calcareous
National code/
River type name
Hydromorphological quality elements

Biological quality elements
Ecosystem Services
EU Directives
Project size 2.3 km
Approximate costs > 1 000 000 Euros
Synergy flood protection, river bed stabilisation
Status Realised
Period of realization 2006-2011
Evaluation Hydromorphological changes
Implemented by Federal Ministry of Agriculture, Forestry, Environment and Water Management

Key features of the case study

The study site of the 6th order alpine stream has a total length of 5,5 km. Hydrological classification corresponds with a moderately nival discharge regime with a distinct annual character. The nowadays heavily modified river within its remains of riparian forests flows through a monotone canal-like channel with a corresponding degraded aquatic community. The start of sustainable river regulation measures was set in 1885. Dams were raised in order to prevent the self steering widening of the water caused by flood events. Several bayous were cut off from the main river bed. The downward gradient was increased by straightening the Traun river over the whole reach of the study site. The transport capacity of the new river bed was optimized hydraulically. The river width was reduced dramatically. The river bed was lowered around several meters over the period of 100 years cause of the increased transport capacity. The whole river restoration project is planned to be fulfilled as gradual development. The first section with a total length of 2,3 km which is presented as case study has already been completed in 2011. Projects for the remaining sections have not yet been concluded but they are planned to be implememted over the next years.

Site description

The Traun is a right tributary of the Danube, which it meets near the City of Linz in Upper Austria. With a total length of 73 km and a total catchment area of approx. 4278 km², the Traun river is one of the largest rivers in Austria.

Measures selection

Success criteria

Ecological response

Hydromorphological response

Monitoring before and after implementation of the project

Socio-economic aspects

Contact person within the organization

Extra background information

As natural running waters are subject to self-steering dynamic processes in the lapse of time several site descriptions and historical maps of the Traun stream course and dthe river bed morphology were analysed. The stream course of the Traun river out of 17th century local maps, maps from 1763 – 1787 (Josephini land survey), 1805 – 1869 (Franciscan survey map), from 1869 – 1887 (Franciscan - Josephini land survey) and from the river regulation project from 1885 has been digitized and combined with the present state of the actual aerial view.


Related Measures

Related Pressures