At 9am on Tuesday 30 January 1607, the tide in the Bristol Channel rose and didn't stop rising. To the horror of people living along the coast, it continued to rise until “mighty hills of water”, as eyewitness William Jones put it, flooded into the low-lying land of Somerset, North Devon and South Wales.
The flooding was swift, “faster than a greyhound can run”, and devastating. It's impossible to find a truly accurate tally but the death toll is estimated to have been between 500-2000 people. Countless animals drowned as the waters reached Glastonbury deep in the heart of Somerset and Monmouth high up the Wye Valley.
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Jones, a Puritan propagandist, wrote vividly of what he saw: “Sometimes it so dazzled the eyes of many of the Spectators, that they imagined it had been some fog or mist, coming with great swiftness towards them: and with such a smoke, as if Mountains were all on fire”.
Of the immediate aftermath he recalls poignantly: “There is little now remaining there to be seen, but huge waters like to the main ocean: the tops of churches and steeples like the tops of rocks in the sea... Many there were which fled into the tops of high trees, and there were inforced to abide some three daies, some more.... beholding their wives, children, and servants, swimming (remediles of all succour) in the Waters. Other some sitting in the tops of Trees might behold their houses overflowne with the waters. some their houses caryed quite away: and no signe or token left there of them”.
Jones reported that many saw this inundation as an act of God: “a second deluge [Great Flood]: or a universal punishment by Water”. But modern scientific analysis has settled on two main theories. In 2002, Ted Bryant of University of Wollongong, Australia, and Simon Haslett of Bath Spa University proposed that the so-called 'Bristol Channel Flood' was a tsunami, caused either by an enormous landslide on the edge of the continental shelf deep underwater or an earthquake. There are indeed reports around the time of the flood that mention tremors, although the timing of these is disputed. Haslett and Bryant also pointed to the descriptions of the height of the waves and that large boulders have been found swept inland, which might testify to the velocity of a tsunami.
The tsunami theory
However, the tsunami theory was countered in 2006 by Kevin Horsburgh of the University of Liverpool and Matt Horritt of University of Bristol who used computer modelling to reproduce a typical storm surge in the Bristol Channel and also mapped out a hypothetical tsunami. They concluded that the flood was probably a storm surge – a combination of an exceptionally high spring tide coupled with gale force winds driving the sea towards shore.
A similar devastating storm surge occurred more recently on 31 January 1953. The North Sea Flood was a combination of a high spring tide and a severe north-westerly gale. Vast areas of low-lying East Anglia, Lincolnshire, Belgium and the Netherlands were flooded and 2000 people died included 307 in the UK. Something similar is likely to have occurred in the Bristol Channel 450 years earlier.
So far, such events are very rare and, with better sea defences and early warning systems, we are more prepared than our ancestors. However, rising sea levels and increasingly violent and unpredictable weather caused by a changing climate might lead to more storm surges and devastating coastal flooding.
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