HyMoCARES

Alpine Rivers are working for Us

Study site

The river Salzach leaves the northern eastern Alps near the town Salzburg and flows along the Austrian and Bavarian border through the Alpine foothillsThe river has its source in the Kitzbühler Alpen/Österreich at a height of 2300 m a.s.l. and flows into the Inn (344 m a.s.l.); its total length is 225 km.  In 1817 the river Salzach was a braided river. In the past 100 years, the river moved to a monotonous and straight river morphology due to various human activities such as widh reduction, bed load retention in the upstream catchment and gravel extractions. As a consequence, a significant incision of the river bed (up to 5 meters in approximately 100 years) has been observed causing a significant lowering of the groundwater table. In addition, the risk of sudden river-bed break-through, especially during floods, increased as demonstrated by some events near Salzach (Amt der Salzburger Landesregierung 1969).

Historical variations, location and view of the Salzach river in the pilot area reach (Photo: Stockhammer, 2004).

 

Restoration project

The restoration site “Lower Salzach” is located between 15 km in the north of the town of Salzburg to the confluence of the Salzach and the river Inn. The main aims of the restoration project (started in 2008) are: i) raising river bed and water level, ii) reducing the risk of sudden river-bed break-through, iii) widening the river bed by a self-acting bank erosion and iv) restoring the connection with adjacent wetlands and floodplains. To reach these objectives the following actions have been implemented: construction of a rip rap-section/revetment for stabilizing the river bed, construction of a step & pool ramp and the partial removal of some bank protections.