Flood risk concepts 1631 Standard of protection

For many years the paradigm in flood management was to 'protect' or 'defend' against flooding, typically through a combination of engineered structures like flood banks or storage reservoirs and channel maintenance to improve conveyance of flood waters downstream. In this approach, the performance of the flood defence is typically expressed as a 'standard of protection' (SoP; see Fig. 16.1). The SoP represents what size of flood the defence should protect against, usually written in terms of the return period. In design calculations, the SoP would be used to determine the crest level of a flood bank or size of a storage pond.

Water level

Fig. 16.1 Channel cross-section with flood bank showing the definition of standard of protection (SoP)

in terms of return period (RP). The difference between the SoP level and the actual crest level of the defence is a freeboard allowance.

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