Kassel study: barrage management can reduce floods

Weather extremes have repeatedly led to flooding in recent years. Where large rivers are affected that are regulated by barrages, these structures could noticeably reduce floods. This is the result of an elaborate study conducted by Prof. Dr.-Ing. Stephan Theobald and Dr.-Ing. Sarah Dickel of the University of Kassel for the Bavarian State Office for the Environment. They examined the corresponding potential of the numerous barrages on the Inn River in Bavaria, where, for example, a major flood in 2013 caused devastating damage in Passau, as well as in numerous other towns. At the time, the Inn reached a record level of 11.60 meters (Passau Ingling gauge), the Danube of 12.90 meters (Passau gauge).

The Kassel researchers concluded that adapted, intelligent barrage management can lower the level by eight to 23 centimeters (Passau Danube gauge) and 17 to 45 centimeters (Schärding Inn gauge) during flood events of different magnitude. The peak discharge of the flood measured at the Passau-Ingling power plant could be reduced by two to nine percent. The study also looked at superimposing a measurement-based control of a flood gate; the combined control achieves water level reductions of 17 to 36 centimeters at Passau and as much as 23 to 68 centimeters at Schärdung. "Barrage management cannot prevent flooding, but it can make a noticeable contribution to flood protection," commented Prof. Theobald. "Even ten or 15 centimeters can make a significant difference for many communities and many homeowners, especially during major floods."

The prerequisite, he said, is to skillfully coordinate the operation of the barrages during flood warnings. This, he says, is made possible by a complex modeling program developed by the scientist and the researcher at the Department of Hydraulic Engineering and Water Resources Management. In simple terms, this involves first lowering the water levels in front of the barrages during a flood warning or forecast and then raising them again at the right time in each case in order to retain water in the reservoir area of the barrages and flatten the crest of the flood wave. 

The study area comprised the Inn River from the Oberaudorf power plant to its confluence with the Danube in Passau, as well as the section of the Danube as far as Jochenstein. Fifteen power plants were considered, eight of which were included in the control. The method can be transferred to other river systems - how large the effect is then depends on the particular characteristics of the watercourse and the barrages.

The study was part of an overall project, the results of which can be found here:
https://www.cee.ed.tum.de/wb/projekte/retentionspotentialstudie-am-inn/

Contact:

Prof. Dr.-Ing. Stephan Theobald
University of Kassel
Department of Hydraulic Engineering and Water Management
E-mail: s.theobald[at]uni-kassel[dot]de