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Understanding Flood Risk

The article gives an overview of flood risks in the UK. In this article, the readers will learn about what flood risks are.

An overview of risk in the UK.

How can individuals access information regarding flood risk to their property?

The readers will also learn about The Environment Agency’s maps and how to access information regarding flood risks.

Flood risk history of a property by postcode.

Flood risk for planning.

Flood risk assessment.

Flood Risk

Flood risk is determined by combining the probability of a flood occurring and the consequences if it happens. Flood risk depends on the existence of a flood source, i.e., a river, a water passage, and the receptor, i.e., any property at risk of being affected by the flood. Without a pathway that connects the source to the receptor, a flood would be categorised as a hazard, not a risk. Therefore, the probability of occurrence of a flood hazard and the vulnerability of assets to that determines flood risk.

What is the risk of floods?

Flood risk is a combination of the probability of a flood hazard occurring and the consequences of such events. Flood risks impact a country’s infrastructural, social, and economic conditions. In addition, floods have implications for the health and well-being of people.

What is 1 in 100 flood risk?

The phrase 1 in 100 flood risk has been mistakenly understood as a flood that occurs once every 100 years. It actually means that there is a 1% chance of flood in the given area in any year. The phrase is used to distinguish regions falling in flood zone 2 and 3 with a medium and high probability of flooding.

What does flood factor 1 10 means?

The flood factor indicates a comprehensive 30-year risk of flooding to a property. Flood factor ranging from 1-10 suggests the risk of flooding from streams and rivers, rainfall, storm surge, and high tide. Buildings with less than a 0.2% chance of flood reaching their footprint are considered flood factor 1 or at minimal risk.

What does 1% flood mean?

The phrase 1 in 100 flood risk, is the same as 1% flood risk. It means in any given area, there is a 1% of chance of flooding from any source in a year. In the UK, flood zones 2 and 3a have a 1% or higher flood risk, respectively.

Flood risk in the UK

According to the reports of The Environment Agency, 1 in 6 properties is at risk of flooding in England. 2.4 million properties in England are vulnerable and at risk of flood from sea and river. Surface water flooding threatens 3 million properties, and around 600,000 properties are at risk of all forms of flooding. These numbers are likely to increase with climate risk.

Flood Risk Along the river Thames in Oxford

Which areas of the UK are most at climate risk from flooding?

The risk of flooding across the UK is accelerating because of climate change. According to new research top, the ten local authorities at most risk of flooding by the year 2050 are

  1. Cardiff, Wales
  2. Windsor and Maidenhead, England
  3. Warrington, England
  4. London borough of Barking and Dagenham
  5. Neath Port Talbot, Wales
  6. Scottish Borders, Scotland  
  7. Rhondda Cynon Taf, Wales
  8. West Berkshire, England
  9. London borough of Greenwich
  10. Clackmannanshire, Scotland

What are the 3 main causes of floods?

Flooding happens when water overflows into ordinarily dry land. Water overflow occurs from rivers and sea, surface water, drainage, and reservoirs. The leading causes of flooding in the UK, according to The Environment Agency, are population growth and a reduction in green spaces. These factors increase flooding rates and risks when combined with extreme weather conditions.

The Environment Agency Flood Maps

The Environment Agency is central to flood risk emergency management at all levels. The Environment Agency is also responsible for strategic flood risk management for all sources of flooding, i.e., river and sea flooding, reservoirs, surface water, and groundwater flooding.

The Environment Agency Flood Risk maps show the long-term river and sea flooding risks. The maps provide information regarding the extent of flooding, depth, velocity, and degree of risk. The Environment agency maps provide flood risk information for all areas of the UK. These maps are part of the strategic flood risk assessment.

Flood Risk By Postcode

Flood risk by postcode allows the viewers to access flood risk information for every property in England. The Environment Agency Flood Maps allow users to enter their postcode, check for flooding, and see the extent to flood risk in their area. The flood risk maps of Urban Water also provide information on flood risk for all areas of England. In the Urban Water flood map tap, users can see the flood risk to their properties by entering their postcode.

How do I know if my property is in a flood zone UK?

You can access flood risk information from The Environment Agency website. In London, every borough has its flood risk assessment report. In addition, flood risk assessment agencies like Urban Water can provide you with information regarding flood risk to your property. Flood assessment agencies like Urban Water can perform flood assessment tests for your property if you are planning a development.

Flooding history by postcode

The best way to access a property’s flood history is to send an inquiry to The Environment Agency. An enquirer can email their address and postcode to the Environment Agency at

If the address and postcode are unknown, a person can also send a map of the area or include an online link to the map. However, the Environment Agency might not have been able to provide the flood history of every property. In such cases, individuals can redirect their inquiries to the local authorities or flood risk assessment experts. Urban Water also provides flood risk for properties in England.

Where is the biggest flood in the UK?

The most recent biggest flood in the UK was Strom Eunice which happened in February 2022. It is one of the most devasting storms experienced in the UK’s history. Millions of people experienced disruption when record-breaking winds of Strom Eunice hit. Four people died, and many suffered injuries. It created substantial structural damage, power cuts, and transport chaos.

 Is UK flooding getting worse?

Like most of the world, the UK’s flooding is getting worse. Storms and flooding occur more frequently, creating financial crises and costing people their homes and lives. There has been an increase in the sea level, which is gradually eroding land around British Isle. Cities are experiencing more heat waves and heavy rainfall, however managing national flood risk is a priority for the LLFA.

Flood risk for planning

Flood risk for planning requires the identification of flood hazards and potential consequences at an early stage of the planning process. Developments must be allocated in areas with minimal or nonexistent flood risks and the project must assess a flood warning.

It requires all constructions, including transport, residential and commercial buildings, and utility infrastructure, to be allocated in low-risk areas. The guidelines also suggest that development should not be allowed in high-risk regions unless there are no alternative options. If it is necessary to have a development in a high flood-risk area, appropriate land use must be adopted.

Who is most at risk of flooding?

In the UK, the properties in flood zones 2, 3a, and 3b are at the most risk of flooding. When we analyse the social consequences of floods, the economically underprivileged segment is at the most risk of flooding. For example, 61% of low-income renters in the UK do not have an insurance program for home contents. That makes them the most financially susceptible segment in society to flooding.

What is Flood Zone 3 UK?

The planning authorities have divided areas in the UK into flood zones to determine the flood risk of a location. For example, the planning authorities have divided flood zone 3 into two parts, flood zone 3a and 3b. Areas in Flood zone 3 have been shown to have 1% or higher chances of flooding from a river or 0.5% or higher chances of flooding from the sea.

Flood risk assessment

A flood risk assessment, also called FRA, is a report that contains details about flood risk to a development site. An FRA is needed in planning and application for new development. The authorities might refuse the development application if the FRA report is not done correctly.

The risk tool allows planners, developers, and property owners to understand an area’s climate risk. Some areas must carry out flood assessments for their proposed development site. Flood assessment at an early stage of planning can save a lot of time and money. 

In the UK, flood assessment is required for development if it falls into the following categories.

1. If the site for development is located in flood zone 2 and 3, this applies to minor development and change of use too.

2. If the development needs more than one hectare of land in flood zone 1.

3. If the development is in risk zone 1, which has critical drainage issues as notified by The Environment Agency.

Where should I live to avoid flooding the UK?

In the UK, the areas in flood zone 1 have a low probability of flooding from rivers and sea. However, there has been an increase in sea level, and it is better to avoid living near the coast, specific areas like Cornwall East coast areas. Likewise, avoid living in Essex, Kent, Cambridgeshire, and Lincolnshire to be safe from river flooding.

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Argemiro Rivera, <b>BEng(Hons) MSC CEng MICE MCIWEM C.WEM CEnv</b>
Argemiro Rivera, BEng(Hons) MSC CEng MICE MCIWEM C.WEM CEnv

Passion for Water, Flood Risk & Sustainability
I love to dig into complex flood risk and water engineering projects and deliver them. I focus on delivering reliable flood risk information to protect livelihoods and the environment.

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