Is development in the defended floodplain at greater risk than development in the undefended floodplain?
The answer to this question depends on how flood risk is managed, including catastrophic failure of a flood defence. Areas that flood but are unprotected would generally be at greater probability of flooding more regularly. However, because of that, any development in these areas would be designed to cope with this recurrent condition, therefore the consequences of flooding would generally be lower. This means risk, which is the product of probability times consequences, would be manageable. When building behind defences, the probability of flooding is reduced, particularly when built areas are defended to a very high standard such as in South Essex. However, for historical reasons and because of this high degree of protection, development has taken place extensively up to the edge of the flood defence and is likely to continue to take place in the future. This means that if the flood defence was to fail, the consequences in terms of risk to life and damage to property would be extreme
