The North Sea flood of 1953, also known as the Big Flood or East Coast Flood (in England) or as the Flood Disaster (Dutch: Watersnoodramp), was a flood caused by a heavy storm surge in the North Sea that struck low-lying coastal areas of the Netherlands, Belgium, and the United Kingdom. More than 2,000 people were killed on land and hundreds more at sea. It was the worst natural disaster of the 20th century in the United Kingdom and the worst in the Netherlands since the Middle Ages.
The storm and flooding occurred during the night of Saturday, 31 January to the morning of 1 February 1953. A combination of a high spring tide and a severe European windstorm caused a storm tide of the North Sea. Most sea defences facing the surge were overwhelmed, resulting in extensive flooding. The combination of wind, high tide, and low pressure caused the sea to flood land up to 5.6 metres (18 ft 4 in) above mean sea level.
Realising that such infrequent events could reoccur, the Netherlands and the United Kingdom carried out large studies on strengthening of coastal defences. The Netherlands developed the Delta Works, an extensive system of dams and storm surge barriers. The UK constructed storm surge barriers on the Thames Estuary and on the Hull where it meets the Humber Estuary.
At the time of the flood, 20% of the land of the Netherlands was below mean sea level (subsequently, with the expansion of Flevoland, this proportion has increased), and the next-highest 30% sat at less than 1 metre (3.3 ft) above sea level. Such land relies heavily on sea defences and was worst affected, recording 1,836 deaths and widespread damage. Most of the casualties occurred in the province of Zeeland.
In England, 307 people were killed in the counties of Lincolnshire, Norfolk, Suffolk and Essex. Nineteen were killed in Eastern Scotland.
Twenty-eight people were killed in the north of West Flanders, Belgium.
More than 230 deaths occurred on seacraft along Northern European coasts as well as on ships in deeper waters of the North Sea. The Stranraer–Larne car ferry MV Princess Victoria sank in the North Channel east of Larne with 134 fatalities, and many fishing trawlers sank. Nine small vessels foundered in the seas around the British Isles with the loss of all hands; these included the Swedish steamer Aspo (22 crew lost), the British steamer Yewvalley (12 crew lost), the British trawlers Sheldon (14 crew lost), Michael Griffith (13 crew lost) and Guava (eleven crew lost), the Dutch motor vessels Salland (nine crew lost) and Westland (eight crew lost), the Dutch trawler Catharina Duyvis (16 crew lost), and the Belgian trawler Leopold Nera (five crew lost).
From midday on 31 January 1953, water was driven from the northern reaches of the North Sea between Norway and Scotland by a strong northwest gale. A storm surge developed along the coast of the Netherlands, which coincided with a high spring tide, leading to many water levels on the Dutch coast on the morning of 1 February 1953 being higher than any previous recorded figures, particularly in the southwestern areas of the country. At 10:30 p.m. on Saturday evening 31 January, it was low tide but, this time, the water remained high. The strength of the hurricane had broken the tidal movement.
On the night of 1 February 1953 around 3 a.m., many dykes in the province of Zeeland and adjacent areas of South Holland and North Brabant proved unable to resist the floodwaters. On both islands and mainland, large areas of the country were flooded.
At 4 p.m. on 1 February, the flood reached a second high. The water rose even higher than during the first flood, and more dykes broke. Many people who had survived the first flood died, as the houses whose rooftops they had sheltered on collapsed due to the persistent water pressure. At that time, the government did not yet know that Schouwen-Duiveland, Goeree-Overflakkee and Tholen were almost completely under water, and no large-scale rescue operations had yet taken place. The depression of the storm was not exceptionally deep compared to previous storms and floods in the Netherlands, such as those which occurred in 1894, 1906 and 1916. However, the storm track was substantially different and propagated at a markedly slower rate than those events. The storm moved east from the Atlantic to the north of Scotland, then curved sharply to propagate into the German Bight, progressing in a south-eastern direction over land. As a result, storm winds from the northwest were stronger and more sustained than the previous events, leading to a higher and longer surge.
Only on Monday 2 February were fishermen the first to sail deep into the disaster area to save hundreds of people. Rescue operations from the air were hardly possible: the Netherlands had only 1 helicopter and had to wait until other countries offered help.
On Tuesday 3 February, a large flow of people and relief supplies started. Planes dropped sandbags, dinghies, boots, food and water over the disaster area. At the same time, thousands of Dutch soldiers, administrators, aid workers and volunteers arrived to carry out coordinated actions in the disaster area. Tens of thousands of residents were being evacuated from the area to shelters elsewhere in the country. Foreign helicopters and amphibious vehicles also came into action on Tuesday, but the vast majority of rescue operations had already been completed by then.
Donations and relief supplies were pouring in at the National Disaster Fund in The Hague. Other countries, including Britain, Sweden and Canada, sent more than 61 million guilders in relief supplies.
Many people still commemorate the dead during the Herdenking Watersnoodramp on 1 February.
Rijkswaterstaat had warned about the risk of a flood. At the time of the flood, none of the local radio stations broadcast at night, and many of the smaller weather stations also only operated during the day. The following broadcast from the Royal Netherlands Meteorological Institute (KNMI) was made at 6.15pm (18:15) on 31 January 1953 on Hilversum Radio:
Over the northern and western parts of the North Sea, a strong gale rages between northwest and west. The storm field is extending further. It is expected that the storm will continue for the whole night, and given this fact, this afternoon at 5.30pm the areas of Rotterdam, Willemstad and Bergen op Zoom have been warned for dangerous high water.
Another warning was broadcast shortly before midnight on 31 January 1953, followed by the Wilhelmus, after which broadcasts ceased for the evening, as was standard in the Netherlands at the time. As a result, the warnings of the KNMI did not penetrate the flood-threatened area in time. People were unable to prepare for the impending flood. The disaster struck on a Saturday night, and hence many government and emergency offices in the affected area were not staffed.
As telephone and telegraph networks were disrupted by flood damage, amateur radio operators went into the affected areas with their equipment to form a voluntary emergency radio network. These radio amateurs provided radio communications for 10 days and nights, and were the only people able to maintain contact from affected areas with the outside world.