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About UsStudy on the flood control effect of Ruhrverband reservoirs
With its eight reservoirs, the Ruhrverband is actively involved in flood management and makes an important contribution to flood control in the areas downstream of reservoirs. However, it is difficult to combine flood management with one of the Ruhrverband’s core tasks: securing the supra-regional supply of drinking water. On the one hand, having a high level of water in the reservoirs makes sense if you want to be able to benefit from the water reserve for as long as possible during dry periods; on the other hand, reservoirs should have as much free storage as possible if they are to provide effective flood control. This conflict is exacerbated by the unpredictability of extended dry or wet periods.
As the Ruhrverband is obliged to reserve some storage capacity during the winter months, the Henne, Möhne, and Bigge reservoirs are not fully filled so that water can be retained in the event of a flood, allowing the water level in downstream river sections to gradually decrease. However, the reservoirs receive only about one quarter of the water in the Ruhr catchment area which is why they can only absorb the peak of high water events.
In major flood events, however, the Ruhrverband reservoirs do contribute quite considerably to reducing run-off - as on August 22nd, 2007, when up to 270 cubic metres of water were retained per second. At that stage, the Hattingen gauge showed a maximum of 772 cubic metres per second. In other words, without reservoirs the flood would have been a great deal higher.
During a flood, reservoir control is coordinated continuously with the district government in Arnsberg which is in charge of the high water warning system along the rivers Ruhr, Lenne, and Volme. Experts believe that, due to climate change, we may see more or heavier floods in future. For that reason, a research project sponsored by the North Rhine-Westphalian Ministry of the Environment currently investigates the flood control effect of Ruhrverband reservoirs in different climatic conditions. Its findings are to help the Ruhrverband face the challenge of flood control in the best possible way now and in the future.
