Repeat of 1607 flood would cost $25 billion

A repeat of the 1607 Bristol Channel floods would cause £13 billion ($25 billion) in insured losses today, according to Risk Management Solutions Inc.

The floods were caused by a major storm surge created by persistent gale force winds and low air pressures, coupled with an exceptionally high tide. Between 500 and 2,000 people were killed in villages and farms along the low-lying coastlines around the Bristol Channel and Severn Estuary.

If the floods were to happen today could raise water levels up to 9.5 meters above sea level in the inner Bristol Channel, above the flood defenses and submerging hundreds of square kilometers of coastal floodplain in the area.

More than 80% of the total losses would occur in the inner Bristol Channel, in the cities of Bristol, Cardiff and Gloucester.

"Current flood defenses might protect areas from a storm surge of up to 8.5 metres, but would not be able to contain a truly exceptional event on the scale of the 1607 floods," said Robert Muir-Wood, chief research officer at RMS.

RMS estimated that the potential cost of a repeat of the 1607 storm would be nearly double the cost of a repeat of the 1953 floods that swept along England's eastern coast.

However, the study estimated that a storm the size of the 1607 floods occurs on average about every 500 to 1,000 years.