Sediment management concept Gail
Research institute: BOKU Institute of Hydraulic Engineering and River Research
The Gail river its tributary rivers are strong bedload-carrying rivers, therefore a bedload retention place was installed 1907.
At the moment there are two main problems on the Gail. The first one is the region around the sediment deposition zone in Dellach in the Gail Valley. Until the year 2007 sediment was taken from the sediment deposition zone. In this area the riverbed is eroding by an average of 2 meters in a length of 10 kilometers.
The second one is the region between the Pressegger Lake and Nötsch. In this area in the last 40 years sediment was deposited on the river banks, the result was a reduction in the cross-section; which resulted in rising water levels. During a LIFE Project three 400 meters long model routes for testing the different solutions for minimizing the aggradation were implemented.
The issue of cavity in the sediment deposition zone and the aggradation between the Pressegger Lake and Nötsch are not enough explored yet. The sediment management concept of the Gail should lead to a better understanding of the processes in the Gail and to an identification and interpretation of the reasons for the existing sediment problems.
For this fundamental data, like sediment input of the tributary rivers, hydrological data, continuity of sediment in check dams, grain-size distribution along the river Gail and hydromorphological data, will be analyzed and assessed. Therefore a sediment monitoring, including a tracer study, analysis of surface and subsurface layer from the river bed, direct and indirect measurements of the bedload transport will be realized.
The resulting bedload balancing should be the fundamental database for the management concept and should help to identify key areas for improvement measures.