What is Residual Risk?
The residual risk is the risk that inherently remains after the implementation of a mitigation measure (option) such as flood defences or raising of floor levels. The Thames Tidal Defences (TTD) reduces the probability of flooding below the threshold of 0.1% per annum. However, more extreme events or conditions may occur and those defences could be overtopped leading to a breach. Risk is not finite and the residual risks associated with living behind any defence must be considered. In the case of South Essex the quality of tidal defence is high and probability of flooding low. However the potential consequences of flooding are very large. The term “Residual Risk” is used for South Essex because a considerable proportion of the risk is being effectively managed by the TTD.
