The frequency of flood loss events is increasing, both regionally and globally, due to the rising population and subsequent development of flood-prone areas, and as a result of environmental and climatic changes. This observation is not universally true for the time series of the losses themselves, at least not in the past one or two decades. One explanation for this is the improvement in flood control and flood protection in certain countries, both for floods that originate in the sea (storm surges) and for inland floods. While the qualitative effect of protection measures – reducing losses – is undisputed, quantitative examples are rare. Performance, or efficiency, needs to be calculated by comparing the costs of investment and maintenance against the losses prevented after a measure was put in place. In this article, a quantitative analysis of the performance of flood control measures is presented for four cases: the storm surge protection of the city of Hamburg, the Mississippi River and Tributary project, the activities of the Tennessee Valley Authority and the Sylvenstein Reservoir in Bavaria. In each case, a significant benefit has been observed in the past decades, proving that flood protection pays off many times over.

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