1953 North Sea Flood
On the night of 31st January and morning of 1st February 1953, devistating flooding occurred around the North Sea coasts of the Netherlands, the UK and Belgium. It was the worst natural disaster to affect the UK in modern times. A deep Atlantic depression that moved down the North Sea combined with spring tides to generate very high storm tides that overwhelmed coastal defences and swamped coastal settlements. There was a large inability for communities to be properly warned of the impending disaster at the time, so many towns had no idea of what was going on before it was too late. 
Preceding the flooding, weather and astronomical conditions coincided perfectly to give rise to large tides. Spring tides were already expected to result in high water levels - a deep Atlantic depression tracked south-eastwards down the North Sea, with strong northerly winds on its western flank. These gale force winds forced water south, down the North Sea, at the time of high tide. The natural shape of the coastline between the UK and the Netherlands acted to funnel the water as it was pushed south. This increased the height of the storm tide and exacerbated the flooding problems. As well as this, the strong winds also generated large waves on top of the tides that eroded sea defences and caused further damage. 
What is a storm surge?
According to the Met Office, it is a change in sea level caused by a storm. Storm surges are well known hazards with tropical cyclones, although in the UK, we experience storm surges generated from Atlantic cyclones. The low pressure in the centre of the storm actually causes the sea level to rise: by about 1 m for every 100 hPa drop in pressure. The cyclone responsible for the North Sea Flood had a minimum central pressure of around 960 hPa, resulting in a 'pressure surge' of about 50 cm. The wind from the storm can also push the surface water towards the coast, which results in coastal flooding. Sometimes, the geography of the coastline itsself can funnel water towards a region and locally worsen the flooding. The geography of the coast in the southern North Sea was one of the factors that made the floods so deadly. 
Surface pressure analysis for 0600 on 1st February 1953. A strong Atlantic depression, with a minimum central pressure of 964 hPa is moving down the North Sea. 
Credit: Met Office. 
The highest tides locally exceeded 5.6 metres above mean sea level and these were able to flood large areas of coastal land. The Netherlands was hit particularly badly - since a large proportion of the country is less than a metre above sea level (around 20% is below sea level). 1,836 people died here, as a result of catastrophic breaches in dykes and sea defences. 70,000 people were evacuated from the worst affected areas, almost 50,000 buildings were damaged, and an estimated 30,000 animals drowned. Almost 10% of Dutch farmland was flooded with seawater - which rendered the land unusable, as the salt water kills crops and makes the ground ungrowable. This had a long term impact on the economy long after the floodwaters receded. 
Meanwhile, the east coast of the UK, notably East Anglia, were hit especially hard. In England, 307 people were killed, while 19 more were killed in Scotland, which was battered hard by the storm surge and violent winds: the maximum gust was 126 mph, at Costa Hill, Orkney. Existing sea defences were destroyed or simply overtopped, leading to the evacuation of 32,000 people and the flooding of 160,000 acres of land. There was significant damage to the infrastructure of many coastal areas: power supplies, transport links (road and rail), sewage and water services were all put out of action. In today's money, the damage total was £1.2 billion in the UK.
Predicted storm surge heights from an ocean model. The highest surge is concentrated in the southern North Sea, as the water is funneled southwards. The southern regions of the Netherlands were the worst effected areas - where the highest storm surge was. Locally, the surge was even higher.
Credit: Environment Agency
Diagram showing the worst affected regions of the UK from the flooding. Parts of central London were also flooded, before the Thames Barrier was built.
Credit: Met Office
The flood was a turning point in the development of coastal defences. After governments realised that there was the possibility for further devistating floods such as this one in the future, they developed schemes to protect their countries from the sea. These new developments ultimately paved the way for sea defences in countries around the world. In the UK, major investments were made to restore and improve sea defences, and the Thames Barries was built as a consequence of the flooding - it was opened in 1984, at a cost of £1.6 billion in today's money, serving the purpose of protecting London from a potential North Sea storm surge. In the Netherlands, a very ambitious flood defence scheme began construction in the 1960s - the Delta Works. It consists of a series of dams, dykes, levees, sluices, locks and storm surge barriers to protect a large area of the Netherlands from storm surges. The Oosterscheldekering is the largest single dam/ storm surge barrier, at 9 km long. 
Aerial view of the Oosterscheldekering dam/ storm surge barrier, illustrating its size.
Close-up view of one section of the Oosterscheldekering.
In the UK, an official service for forecasting coastal flooding was developed: the Tides Warning Centre. This has been integrated into the Met Office and is part of the Flood Forecasting Centre, which is a joint venture between the Environment Agency and the Met Office. Advanced atmospheric and ocean models used by the Met Office and other meteorological/environmental institutions (in other countries), provide early warning of these flood events, and can more accurately forecast where and how significant the flooding will be. These improvements, along with the advances made with flood defences, have minimised the impacts of more recent storm surges. This is quite an achievement, given the steady rise in sea level we are experiencing.
Example of the catastophic flooding in the UK.
Credit: Associated Press