Development and implementation of ecological and economical flood protection measures at an alpine river

¹ Institute for Hydraulic Engineering and Calibration of Hydrometrical Current-Meters, Federal Agency for Water Management, Severingasse 7, 1090 Vienna, Austria
² Breuß Mähr Bauingenieure GmbH, Ingenieurbüro für Kulturtechnik u. Wasserwirtschaft, Straßenbau, Flussbau und Wasserkraftanlagen, Werben 19, 6842 Koblach, Austria
³ Amt der Vorarlberger Landesregierung, Abteilung Wasserwirtschaft, Josef-Huter-Straße 35, 6901 Bregenz, Austria

^* Corresponding author: ursula.stephan@baw.at

Abstract

The river Lutz as many other rivers in Austria was forced into a straight and narrow river bed. Several weirs were erected to stabilise the river bed, but which, too, impeded organism passability. After decades with several floods the protection measures were in bad condition. In 2005, a 500-years flood caused heavy damage along the river and destroyed a main railway line. This incident initiated comprehensive planning activities to improve both, the flood protection as well as the ecological status of the river. Several technical measures focussing on stabilising the river bed, increasing the discharge capacity and improving the ecological status such as a step-pool-ramp with variable width, an open rip-rap, an increased river width as well as embankment groynes as an ecological and dynamic bank protection instead of a bank reinforcement were proposed. These measures were tested for feasibility and optimized in a physical model experiment.