Lee Flood Relief Channel

Flood defences are rated according to the probability that a particular level of flood water will be exceeded at least once in a specific period, so a 100-year flood represents a level that would only be expected to occur once in 100 years. This is often known as 1 per cent protection. The level of flooding in 1947 was estimated to be a 1.4 per cent occurrence, and the flood channel, when it was first designed, was built to cope with this level of flooding. Since it was completed in 1976, there have been no major flood events in the Lea Valley, although there have been three occasions when the river system was full virtually to its capacity: in 1987, 1993 and 2000. Since its completion, the…