Introduction^[1]

Britain’s killer wave of 1607, often referred to as the Bristol Channel Flood, was a catastrophic event that struck the southwestern coastlines of England and Wales – it occurred around 9 am (but some reports say noon) on 20^th January 1606, although in the modern calendar, this is the 30^th January 1607. The disaster resulted in significant loss of life and widespread destruction, with an estimated 2,000 deaths and thousands of hectares of farmland submerged under flood water. The event remains one of the most devastating natural disasters in British history.

The Event
On that fateful day, a massive wave surged through the Bristol Channel, inundating low-lying areas – the flooding stretched as far as the Glastonbury Tor 14 miles inland, and flooded 200 square miles of Somerset, Devon, Glamorganshire and Monmouthshire. Coastal towns, villages, and agricultural lands were overwhelmed within a short period, leaving little time for people to escape. Reports from the time describe the wave as sudden and ferocious, sweeping away entire communities, livestock, and crops. The floodwaters reportedly reached as far as 14 miles inland in some areas.

The devastation was particularly severe on the Welsh side, extending from Laugharne in Carmarthenshire to above Chepstow in Monmouthshire. Cardiff was the most badly affected town.^[2]

Contemporary accounts speak of churches being filled with water, people climbing onto rooftops for safety, and survivors clinging to debris. The destruction left behind was catastrophic, not just in terms of immediate deaths but also the longer-term economic impact due to the loss of crops, homes, and infrastructure.

Depiction of the 1607 Bristol Channel flood with St Mary’s Church at Goldcliff, Monmouthshire. The scene shows turbulent flood waters and people and animals struggling amidst the chaos.
Drawn by DALL-E, a subset of ChatGPT, 25^th November 2024.

Possible Causes
For centuries, the cause of the killer wave was debated. Traditionally, it was believed to be a storm surge caused by a combination of high tides, strong winds, and low pressure. However, modern research has introduced the possibility that it could have been a tsunami triggered by an underwater landslide in the Atlantic Ocean or seismic activity near the fault lines in the region.

Proponents of the tsunami theory point to the speed and suddenness of the wave, as well as similarities with later confirmed tsunamis. However, others argue that the geographic features of the Bristol Channel are more conducive to storm surges amplified by funnelling effects. The precise cause remains a topic of scholarly debate.

The spring tide in the Bristol Channel on 30^th January 1607 reached a height of 7.86 metres (25 ft 9 in). This occurred in combination with a severe south-westerly gale with peak winds measured at Barnstaple from 3 am to noon and coastal flooding in East Anglia at night on the 30^th, both of which are consistent with a storm tracking eastwards.^[3] It has been demonstrated that the tide and weather event that occurred on this date were capable of generating a storm surge consistent with the observed inundation.^[4]

Legacy
The 1607 flood had a profound impact on the communities along the Bristol Channel, leading to a greater awareness of the dangers posed by the sea. In its aftermath, many religious interpretations emerged, with the event seen as divine punishment or a warning. Some surviving churches in the affected areas still bear high-water marks from the flood, a haunting reminder of the disaster.

Picture: Flood plaque, in St Mary’s Church, Goldcliff, near Newport.
This plaque marks the height of a flood of approximately 5 feet that occurred on the 20^th January 1606 (modern calendar 30^th January 1607).
Attribution: Robin Drayton / Flood plaque, Goldcliff Parish Church
This file is licensed under the Creative Commons Attribution-Share Alike 2.0 Generic license.

Modern flood defences along the Bristol Channel are, in part, influenced by historical knowledge of this event. The killer wave of 1607 remains a stark reminder of nature’s unpredictable power and the enduring vulnerability of coastal regions.

Eyewitness Accounts
Contemporary records, particularly from local clergymen and diarists, provide vivid descriptions of the disaster. One account describes how the water came “with such force and swiftness that no tongue can express, nor pen write.” People were swept away before they could flee, and survivors recounted scenes of utter devastation. Churches became temporary refuges, though many were inundated. One particularly famous marker, etched in a church in Goldcliff, Monmouthshire, records the flood’s height, serving as a sad reminder of the tragedy.

The most detailed information for a single town is found in the Lost Chronicle of Barnstaple, compiled by Dr Todd Gray of Exeter University in 1998 from records written between 1586 and 1611 by the Barnstaple town clerk, Adam Wyatt^[5].

A pamphlet, ‘Gods’ warning to his people of England’, authored by William Jones^[6] of Usk, offers a detailed account of the catastrophic flooding. Jones describes the floodwaters as “huge and mighty Hilles of water, tumbling one over another,” likening them to “the greatest mountaines, in the world, had over-whelmed the lowe Valeyes or Marshy grounds.” He further notes that the approaching waters “dazled the eyes of many of the Spectators,” appearing as “some fogge or miste, comming with great swiftnes towardes them.” These descriptions underscore the suddenness and overwhelming nature of the flood, which led to significant loss of life and property. The pamphlet serves as both a historical record and a moral commentary, interpreting the disaster as a divine warning to the people of England. Such publications were common in the early 17^th century, often framing natural calamities within a religious context to encourage societal reflection and repentance.^[7]

The full version of William Jones’ message was:
“For upon the Tuesday being the 20 of January last É about nine of the clocke in the morning, the Sunne being most fayrely and brightly spred, many of the Inhabitantes of those Countreys before mentioned, prepared themselves to their affayresÉ. Then they might see & perceive a far of, as it were in the Element, huge and mighty Hilles of water, tumbling one over another, in such sort as if the greatest mountaines, in the world, had over-whelmed the lowe Valeyes or Marshy grounds. Sometimes it so dazled the eyes of many of the Spectators, that they immagined it had bin some fogge or miste, comming with great swiftnes towardes them: and with such a smoke, as if Mountaynes were all on fire: and to the view of some, it seemed as it: of thousandes of Arrowes had bin shot foorth all at one time, which came in such swiftnes, as it was verify thought, that the Fowles of the ayre could scarse fly so fast, such was the threatning furyes thereof.”

While William Jones’ pamphlet conveys a religious message, it also resembles early journalism. He includes a series of personal stories about individuals affected by the flood, similar to the human-interest focus found in newspaper reports.^[8]

Religious Interpretations

In 1607, the cultural and intellectual context of the time meant many people attributed the disaster to divine wrath. Sermons following the flood described it as God’s punishment for the sins of the people. Religious pamphlets and writings proliferated, warning of the consequences of moral failings. This theological interpretation was a common response to natural disasters in the pre-modern era when scientific understanding of such events was limited.

Economic and Social Impact

The flood devastated local economies, particularly in agricultural regions. Livestock was drowned in the thousands, and fields of wheat and barley were ruined by saltwater intrusion. This led to famine and economic hardship in the years that followed, as farmland remained unusable for some time. Entire villages were abandoned, and the survivors faced the monumental task of rebuilding their lives and homes.

Socially, the disaster created a shift in settlement patterns, with some communities relocating to higher ground. The psychological toll was significant as well, with the memory of the flood lingering for generations and shaping local traditions and folklore.

The Cause: Modern Investigations

Interest in the killer wave of 1607 was reignited in the late 20^th and early 21^st centuries when researchers began to question the storm surge hypothesis. The tsunami theory, first proposed in the early 2000s, gained support due to the wave’s sudden appearance and the extensive reach of the flooding. Investigations into sediment deposits in the region have sought to find evidence of tsunami-like characteristics, such as the types of sand and debris carried inland. However, the absence of definitive seismic records from 1607 makes it difficult to confirm this theory conclusively.

Another possibility is that the flood was the result of a meteotsunami^[9], a rare phenomenon caused by atmospheric pressure changes that displace large volumes of water. Understanding meteotsunamis is crucial for coastal safety, as they can occur with little warning and have the potential to cause significant damage.

You can see a visual explanation of a meteotsunami at: https://www.youtube.com/watch?v=lx3rTxu8gGw.

The geography of the Bristol Channel, which narrows significantly as it approaches the Severn Estuary, would amplify such a wave, similar to the way a funnel increases water pressure.

The British Geological Survey has suggested that, as there is no evidence of a landslide off the continental shelf, a tsunami would most likely have been caused by an earthquake on a known unstable geologic fault off the coast of southwest Ireland, causing the vertical displacement of the sea floor.^[10] One contemporary report describes an earth tremor on the morning of the flood;^[11] however, other sources date this earthquake to a few months after the event.^[12]

Lasting Legacy

The killer wave of 1607 remains an important case study for understanding flood risks in the UK. It has contributed to modern flood modelling and the design of defences along the Bristol Channel and Severn Estuary, areas still vulnerable to extreme tidal surges. The event has also become a point of interest for historians, geographers, and climatologists, as it represents an intersection of natural disaster, human response, and cultural interpretation.

In popular culture, the 1607 flood has inspired various forms of creative expression, from poetry and art to documentaries exploring its causes and consequences (see below). It serves as a sobering reminder of how vulnerable human societies are to the forces of nature, even in the modern age of advanced technology and early warning systems.

Here are some notable examples:
Poetry and Prose:

• Contemporary Pamphlets: In the aftermath of the flood, pamphlets such as “God’s Warning to the People of England by the Great Overflowing of the Waters or Floods” were published, offering poetic and prose accounts of the disaster. https://en.wikipedia.org/wiki/1607_Bristol_Channel_floods

Art:

• Woodcut Illustrations: A contemporary woodcut image titled “A true report of certaine wonderfull overflowings of waters, now lately in Summerset-shire, Norfolke and other places of England…” depicts the devastation caused by the flood, showing houses and villages being swept away. https://art-landscape.blogspot.com/2011/03/portraying-bristol-channel-floods-1607.html

Documentaries:

• “The Killer Wave of 1607”: This BBC Timewatch documentary, first aired in 2005, investigates the causes of the 1607 flood, exploring theories such as a storm surge or a tsunami. https://www.imdb.com/title/tt0875518/
• “A Tsunami in South Wales? The 1607 Flood in the Bristol Channel and Severn Estuary”: A seminar held in March 2021, featuring Professor Simon Haslett, discusses historical and geographical evidence suggesting that the 1607 flood may have been due to a tsunami. https://www.alumniweb.ox.ac.uk/jesus/events/celebrating-the-welsh-college-tsunami-in-south-wales

These works reflect the enduring impact of the 1607 flood on cultural and historical narratives, inspiring creative interpretations across different mediums.

The Scale of the Disaster

The Bristol Channel Flood of 1607 caused immense damage across 520 square kilometres of land. The floodwaters reportedly travelled up to 14 miles (22 km) inland, affecting both sides of the Bristol Channel, particularly the low-lying areas of Somerset Levels in England and Gwent Levels in South Wales. The tidal surge covered more than 200 square miles of farmland, destroying crops and killing livestock in its path.

Estimates suggest that the wave was between 7.5 and 8 metres (25–26 feet) high, particularly as it surged inland. This height is considered unusually large for a storm surge, lending weight to theories such as a tsunami or meteotsunami.

Casualties
Contemporary reports estimate that at least 2,000 people lost their lives in the disaster, though the true number could be higher. These deaths occurred primarily through drowning, as many people were caught off guard by the speed and ferocity of the wave. The death toll also included indirect casualties in the months and years following the event, as famine and disease spread due to the destruction of agricultural resources and contamination of drinking water.

Economic Damage
The economic impact was severe. Thousands of acres of farmland were inundated with saltwater, rendering the soil infertile for several years. Historical records indicate that many families lost their livelihoods, as their homes, livestock, and crops were swept away. Entire herds of cattle and sheep, crucial to the local economy, were drowned.

At the time, the Somerset Levels and Gwent Levels were among the most fertile agricultural areas in the region, meaning the disaster caused widespread food shortages. For context, saltwater can render farmland unusable for several planting seasons, leading to long-term economic hardship in affected areas.

Geographic Reach
The flood caused devastation along the Bristol Channel, with significant impacts recorded in:

• Somerset: Villages such as Kingston Seymour, Brean, and Burnham-on-Sea were heavily affected.
• Devon: Coastal areas experienced flooding and loss of life.
• Gloucestershire: Towns like Gloucester saw churches and homes submerged.
• South Wales: The Gwent Levels near Newport were among the worst-hit areas, with large stretches of farmland destroyed.

The Severn Estuary acted as a funnel, amplifying the wave as it surged inland. This geographical feature, combined with high tides and the unusual nature of the wave, contributed to the unprecedented flooding.

Analysis and Statistics

In modern terms, researchers have tried to reconstruct the event using hydrodynamic models. Some estimates suggest that the volume of water displaced could have been 2 to 3 billion cubic metres, causing the extensive inland flooding documented in historical accounts.

If a similar event occurred today, the damage would likely run into billions of pounds, given the higher population density and infrastructure development along the Bristol Channel. For comparison, the 2014 Somerset Levels flood, which caused significant damage but no loss of life, resulted in costs of over £100 million.

Historical Context
The population density along the Bristol Channel in 1607 was much lower than today, but the communities affected were particularly vulnerable. At that time, flood defences were minimal, and many people lived in low-lying areas close to the sea. Buildings were often constructed of wood and thatch, making them highly susceptible to destruction by water.

Tsunami Probability
If the 1607 wave were a tsunami, it would be one of the only confirmed historical tsunamis to strike the British Isles. A tsunami of similar magnitude would be expected to affect tens of thousands of people today, with devastating consequences for areas like Cardiff, Bristol, and Newport.

The 1607 flood serves as a crucial case study for understanding extreme weather and tsunami risks in the UK. It has inspired both historical and modern efforts to protect vulnerable coastal regions from future disasters.

Comparison with Other Disasters and Floods

The killer wave of 1607 remains one of the deadliest floods in British history, only rivalled by storm surge floods like those in 1570 and 1953 along the east coast of the United Kingdom. For context:

• The 1953 North Sea flood killed over 300 people in the UK but impacted a much wider area.
• The 2021 flooding in Germany and Belgium caused over 200 deaths, demonstrating the enduring threat posed by sudden flooding events.

There have been other catastrophic floods and extreme wave events in Britain both before and after the killer wave of 1607, although the 1607 flood remains one of the most severe in terms of its scale and impact. Notable examples include events such as the tsunami or extreme weather-related flooding that may have occurred in 535–536 AD, linked to global climate disruptions, and the flood of 1014 (see below), mentioned in the Anglo-Saxon Chronicle, which is thought to have been caused by a tsunami or severe storm. Another significant event was the Great Storm of 1287, which brought a devastating storm surge that reshaped the coastline in areas like Rye and Winchelsea. Similarly, the North Sea floods of 1338–1339 caused severe damage to eastern England’s coastline.

The Flood of 1014
On 28^th September 1014, a catastrophic sea flood struck the British Isles, as documented in the Anglo-Saxon Chronicle:

• “This year, on the eve of St. Michael’s Day, came the great sea flood, which spread wide over this land and ran so far up as it never did before, overwhelming many towns and an innumerable multitude of people.“
• Contemporary accounts, such as that by historian William of Malmesbury, describe a “tidal wave… of astonishing size such as the memory of man cannot parallel, so as to submerge villages many miles inland and … .” See: https://www.patriciabracewell.com/2017/09/the-great-sea-flood/
• The event’s suddenness and the absence of storm reports have led scholars to consider a tsunami as the cause. Research has identified sediment deposits containing marine organisms at sites like Marazion Marsh in Cornwall and Chesil Beach in Dorset, dating to the early 11^th century, supporting the tsunami hypothesis. See: https://www.scotsman.com/news/weather/a-tsunami-hit-britain-in-the-11th-century-due-to-an-asteroid-1440206
• The exact cause remains uncertain, with theories including an undersea earthquake, a submarine landslide, or a comet impact in the Atlantic Ocean. Ice core samples from Greenland show chemical signatures indicative of a comet around this time, and astronomical models suggest a close encounter with Earth in 1014, potentially generating a tsunami. See: https://www.scotsman.com/news/weather/a-tsunami-hit-britain-in-the-11th-century-due-to-an-asteroid-1440206
• While the precise cause is still debated, the 1014 flood stands as a significant event in British history, highlighting the region’s vulnerability to natural disasters. See: https://www.thetimes.com/uk/environment/article/the-comet-that-may-have-caused-a-medieval-tsunami-6009mtw07

Picture: Bristol Channel
This image is in the public domain because it contains materials that originally came from the United States Central Intelligence Agency‘s World Factbook.
File URL: https://en.wikipedia.org/wiki/File%3ABristol_channel_detailed_map.png
Author: User:ChrisO – Wikipedia

Floods after 1607
After 1607, extreme flooding events continued to affect Britain:

• The Great Storm of 1703 caused storm surges along the Bristol Channel and extensive coastal damage.
• In 1755, the Lisbon earthquake generated a tsunami that reached parts of western Britain, including Cornwall, causing flooding in harbours such as Penzance.
• A lesser-known flood occurred in 1817 along the Bristol Channel, resembling the 1607 event but with a lower death toll, likely caused by a storm surge.
• The North Sea flood of 1953 was one of the most devastating in modern British history, resulting in over 300 deaths in the UK and leading to the development of flood defences like the Thames Barrier.
• More recently, in 2014, the Somerset Levels experienced severe flooding due to heavy rainfall, highlighting the ongoing vulnerability of low-lying areas. Although no lives were lost, the economic damage was significant, exceeding £100 million.

Future Recurrence

The UK’s National Risk Register^[13] highlights the threat of coastal flooding. Although advancements in defences and flood warning systems have reduced the likelihood of such events in the near future, the potential financial impact remains significant. Estimates suggest that similar flooding could inflict damages between £7 billion and £13 billion (based on 2007 insured values) on residential, commercial, industrial, and agricultural properties. Additionally, there are concerns regarding the vulnerability of nuclear power stations at Hinkley Point and Oldbury to such flooding events.^[14]

The geography of the Bristol Channel, with its funnel-like shape, makes it particularly vulnerable to flooding. Many past events coincided with high spring tides, amplifying their effects. Earlier periods lacked sufficient flood defences, leaving communities exposed to the full force of such disasters. While modern flood management and warning systems reduce the risk of another event like the 1607 killer wave, the region remains susceptible. Events like the 2004 Indian Ocean tsunami and the 2011 Tōhoku tsunami serve as reminders that even areas with no recent history of tsunamis can face significant risks.

Sources and Further Reading

• http://website.lineone.net/~mike.kohnstamm/flood/jonespamphlet/godswarning.html
• https://art-landscape.blogspot.com/2011/03/portraying-bristol-channel-floods-1607.html
• https://en.wikipedia.org/wiki/1607_Bristol_Channel_floods
• https://en.wikipedia.org/wiki/Climate_of_south-west_England
• https://forms2.rms.com/rs/729-DJX-565/images/fl_1607_bristol_channel_floods.pdf
• https://quod.lib.umich.edu/e/eebo/A00015.0001.001
• https://www.alumniweb.ox.ac.uk/jesus/events/celebrating-the-welsh-college-tsunami-in-south-wales
• https://www.bbc.co.uk/bristol/content/articles/2007/01/30/flood_feature.shtml
• https://www.burnham-on-sea.com/history/1607-flood/
• https://www.gethistories.com/p/gods-warning-to-the-people-of-england
• https://www.gov.uk/guidance/updates-to-national-flood-and-coastal-erosion-risk-information
• https://www.imdb.com/title/tt0875518/
• https://www.livinglevels.org.uk/stories/2018/12/10/the-great-flood-1607
• https://www.patriciabracewell.com/2017/09/the-great-sea-flood/
• https://www.scotsman.com/news/weather/a-tsunami-hit-britain-in-the-11th-century-due-to-an-asteroid-1440206
• https://www.surgewatch.org/historic-events-the-british-channel-floods-of-1607-2/
• https://www.thetimes.com/uk/environment/article/the-comet-that-may-have-caused-a-medieval-tsunami-6009mtw07

Books

• The Day the Sea Came In: 1607 on the Gwent Levels, by Rose Hewlett, published by Gloucestershire House Histories, available from https://www.amazon.co.uk/day-sea-came-Gwent-Levels/dp/1916225209/
• The Great Flood of 1607, by Barb Drummond, published by self, available from https://www.amazon.co.uk/Great-Flood-1607-Barb-Drummond/dp/1912829177/
• The Severn Tsunami? The Story of Britain’s Greatest Natural Disaster, by Mike Hall, published by The History Press, available from https://www.amazon.co.uk/Tsunami-Britains-Greatest-Natural-Disaster/dp/0752470159/

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End Notes and Explanations

1. Source: Compiled from my research using information available at the sources stated throughout the text, together with information provided by machine-generated artificial intelligence at: bing.com [chat] and https://chat.openai.com. Text used includes that on Wikipedia websites is available under the Creative Commons Attribution-ShareAlike License 4.0; additional terms may apply. By using those websites, I have agreed to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organisation. ↑
2. Source: https://en.wikipedia.org/wiki/1607_Bristol_Channel_floods ↑
3. Source: K. J. Horsburgh and M. Horritt, M. (2006). “The Bristol Channel floods of 1607 – reconstruction and analysis”. Weather. 61 (10): 272–277.Cited at: https://en.wikipedia.org/wiki/1607_Bristol_Channel_floods ↑
4. Sources: (1) J. Horsburgh and M. Horritt, M. (2006). “The Bristol Channel floods of 1607 – reconstruction and analysis”. Weather. 61 (10): 272–277, and (2) 1607 Bristol Channel Floods: 400-year Retrospective Risk Management Solutions Report (PDF), Risk Management Solutions, Newark CA, USA, 2007. Cited at https://en.wikipedia.org/wiki/1607_Bristol_Channel_floods ↑
5. Source: https://forms2.rms.com/rs/729-DJX-565/images/fl_1607_bristol_channel_floods.pdf ↑
6. Further Information: see http://website.lineone.net/~mike.kohnstamm/flood/jonespamphlet/godswarning.html ↑
7. Source: https://quod.lib.umich.edu/e/eebo/A00015.0001.001 ↑
8. Source: https://www.gethistories.com/p/gods-warning-to-the-people-of-england ↑
9. • Seiches: Standing waves in enclosed or partially enclosed bodies of water, typically caused by prolonged wind or atmospheric pressure changes. Source: https://oceanservice.noaa.gov/facts/meteotsunami.html
   • Storm Surges: Elevated sea levels due to strong winds and low atmospheric pressure from storms, leading to coastal flooding. Source: https://www.britannica.com/story/what-is-the-difference-between-a-meteotsunami-a-seiche-and-a-storm-surge Explanation: A meteotsunami is a tsunami-like sea wave generated by rapid changes in atmospheric pressure, often associated with fast-moving weather systems such as squalls, thunderstorms, or storm fronts. Unlike traditional tsunamis, which are typically caused by seismic activity like earthquakes or underwater landslides, meteotsunamis result from meteorological phenomena. Coastal features such as shallow continental shelves, bays, and inlets can amplify meteotsunamis, leading to more significant impacts on shorelines. Meteotsunamis are often confused with seiches and storm surges:↑
10. Source:  BBC staff (4^th April 2005). “Tsunami theory of flood disaster”. BBC News Online. Retrieved 13^th November 2010. Cited at: https://en.wikipedia.org/wiki/1607_Bristol_Channel_floods ↑
11. Source:  Simon Haslett (2010). Somerset Landscapes: Geology and landforms. Usk: Blackbarn Books. p. 159. ISBN 978-1-4564-1631-7. ↑
12. Source: Albert Zijlstra (16^th June 2016). “The Bristol Tsunami”. Volcanocafe. Retrieved 10^th April 2018. Cited at: https://en.wikipedia.org/wiki/1607_Bristol_Channel_floods ↑
13. Reference: https://www.gov.uk/guidance/updates-to-national-flood-and-coastal-erosion-risk-information ↑
14. Cited at: https://en.wikipedia.org/wiki/1607_Bristol_Channel_floods ↑