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Understanding Flood Maps for Effective Planning

In this article, readers will learn about


    • Flood Maps

    • Importance of Flood Maps in Planning

    • Flood Risk Assessment for Planning

    • Flood Zones and Planning

    • Accessing Flood Maps Online

    • Benefits of Flood Mapping in Planning

    • Future Trends in Flood Mapping and Planning

    • Tips for Effective Planning Using Flood Maps

Flood maps must be provided for every potential project, development, or activity in the United Kingdom. These maps commonly represent possible flood hazards such as rivers, sea, surface water, and groundwater. You can use the flood maps to identify how the floods may affect your development and put preventive measures where necessary.

What Are Flood Maps?

Flood maps are the graphical representations of probable flood locations under diverse sources and circumstances. They are derived from data from preceding years, hydrological and hydraulic models, ground topographies, and climate change projections. They also illustrate the likelihood of flooding, depth, velocity, and length of floodwater exposure.

Flood Map
Flood Map

Importance of Flood Maps in Planning

Flood maps are essential for planning because they help you:

Understand the flood risk

Flood maps will assist in determining whether your specific site area or a certain condition can bring about flooding from any source. Furthermore, this aids you in estimating the level of flooding that is likely to affect your site, for example, the depth of the flood waters, time, speed, level of property damage, and hazard.

Avoid or reduce the flood risk

The best way to minimise the flood risks of your project, development, or activities is by having a reliable flood map flood map and take actions such as raising the floor levels, installing flood barriers, designing drainage systems or even relocating some crucial items.

Comply with the planning policy

Appropriate flood maps can prevent any further flooding if the developments conform with the national and local planning policy that is flood-free and does not increase the flooding risk elsewhere. Moreover, it will illustrate your conformity with the sequential and exception tests for planning applications in flood risk areas.

Role of Environment Agency Flood Maps

The Environment Agency (EA) is the primary public body responsible for managing flood risk from rivers and the sea in the UK. It also manages flood risk from all sources of flooding, including groundwater, reservoirs, and other surface water. One of the significant roles of the EA is to generate and manage flood maps that depict the hazards and implications of flooding in a certain area. These maps are used for various purposes, such as:

 Flood Risk

The Environment Agency Flood Maps are like expert detectives. They analyse and examine different places to determine flood occurrence points. They gather vast amounts of information on rivers, precipitation, and the topographies of land. This enables them to clearly show area that are most at risk.

Sharing Important Information

After collecting all the data, the Environment Agency flood maps do not hide the information. They spread whatever they come across to the rest of the world. This therefore implies that you, local governments, and builders can access those maps online. Knowing the risk helps us make smarter choices.

Helping with Planning

Environment Agency Flood Maps will let you know whether flooding poses potential threats. The land will flood if they tell you so. In this case, consider choosing another site or developing special arrangements for protecting your development,

Flood Risk Assessment for Planning

When applying for planning approval for a development site in the UK, you may conduct an FRA as a part of your application. FRA stands for flood risk assessment and assesses the likelihood and consequences of flooding by multiple causes, namely, rivers, seas, surface water, groundwater, reservoirs and sewers. The FRA also highlights the steps that could be taken to prevent, minimise or manage the flood implications of the site and its surrounding areas.

A flood risk assessment (FRA) helps ensure the proposed development is safe from flooding and does not contribute to flooding elsewhere. It also illustrates that it complies with national and local flood risk management policies.

The FRA should consider the following:

  • The type and scale of the development.
  • The sources of flood risk.
  • Consequence of flooding on the development and its environment.
  • Mitigation measures for flood risk.

The FRA should be submitted with the planning application to the local planning authority. The local planning authority will then determine whether to approve the FRA and other considerations.

Flood Risk Assessment
Flood Risk Assessment

Looking for a Flood Risk Assessment of your Site?

Urban Water is a leading company in flood risk assessment. We offer a range of services for housing, commercial and industrial developments, including sequential and exception tests, flood risk reports for planning applications, and hydraulic river modelling approved by the Environment Agency and water authorities. 

We use the latest data and tools to do your flood risk assessment and produce accurate and reliable flood risk reports that meet the requirements of the National Planning Policy Framework (NPPF) and the Flood Risk Regulations (FRR). 

Flood Zone Designation 1
Flood Zone Designation

Flood Zones and Planning

According to the EA, there are three flood zones designated as Flood Zones 1, 2 and 3 and others.

Flood Zones

Flood Zone 1

Areas classified as flood zone 1 have a less than 0.1 % chance of flooding, sometimes called a 1: 1000 year chance.

Flood Zone 2

Flood zone 2 areas have a 0.1 – 1 % chance of flooding from rivers in any year 1 in 100. Or  0.1 – 0.5 % probability of sea flooding (from 1:1000 and up to 1:200).

Flood Zone 3

Flood zone 3 is split into zones 3a and 3b by local planning agencies. However, in mapping for flood zone 3, EA does not distinguish between these locations. Flood zone 3 involves less than 1 % of river floods and storm floods of less than half a percent.

Flood Zone 3a

A flood zone 3a occurs where the observed probability level exceeds 50% for both sea and rivers. Within this zone is a flood of 100-year recurrence in the river and a sea flood of 200-year recurrence annually.

Flood Zone 3b

Flood zone 3b encompasses an active floodplain, representing the most vulnerable area for flooding due to river or sea overflow. This is typically classed as land with a 3.33% possibility of flooding, sometimes known as a 1:30 chance.

How do flood zones affect planning in the UK?

The planning consequences will vary depending on the type of development and its vulnerability. It is by adhering to the principles of the National Planning Policy Framework (NPPF), especially that of development and flood risk, that PPG guides developers to implement.

Development should be diverted from areas of high risk, and all developments within a high-risk area should be capable of not being subjected itself or causing flooding in neighbouring districts for their full existence period. Developments within Flood Zones 2 and 3 must begin with the sequential test followed by a shift to the exception test only in exceptional circumstances.
In the sequential test, various sites are compared regarding flood risks and the best site for development among them is identified as having the lowest flood risk level. Finally, the exception test applies when all other appropriate sites with low-rise risks are unavailable or if the development generates widespread sustainability benefits rather than flood risks. The exception test has two parts: demonstrating that it is safe during the entire project lifespan but with considerable gains and benefits to the local community, overwhelming the flood risk.

The PPG offers direction on how to perform this FRA and other tests. The PPG provides guidance on how to do site-specific flood risk assessment (FRA), which is required for a planning application. A Flood Risk Assessment (FRA) is a document that identifies and assesses risk from water from outside site boundaries and within the area of your site and suggests actions to avoid risk or reduce it. If your development is in flood zone 2 or 3 and more than one hectare, or if there are problems with critical drainage, you must have an FRA.

The PPG also contains information regarding which type of development can be allowed or not allowed from a flood hazard standpoint in each flood zone according to its flood vulnerability classification. For instance, high-risk development, including residential homes, hospitals or schools, should not pass flood zone 3a or 3b without exception test. Just like that, no essential infrastructure like a power station, water treatment works or emergency services are allowed to exist in flood zone 3b except if the infrastructure’s design can allow them to stay operational even during a flood condition.

Accessing Flood Maps Online

The long-term flood risk for an area in the UK can be determined using flood maps. These demonstrate their potential risks and effects from various sources like rivers, sea, rainwater and reservoirs. In the UK, there exist various ways of obtaining flood maps online that are tailor-made according to one’s preferences and specific requirements. We have these maps in our maps section.

Flood map for planning

The **Flood map for planning** is a government service. This service will tell you if your planning application requires an assessment of flood risk and provide a downloadable printable flood map for planning and flood risk assessment data. This service can be accessed using a postcode, place, national grid reference or coordinates.

Check the long-term flood risk for an area

Alternatively, the government also provides another option of using the **Check the long-term flood risk for an area.** This service tells the overall flood risk and how to manage it over the long term from a number of different directions. You can use this service by entering your postcode or place.

Check for flooding

The fourth option is the **Check for flooding** service, which displays the current flood alert regions and warning zones. This service is provided by the Met Office and the Environment Agency on a regular basis. This can be done by entering your postcode or place or by viewing a map.

Am I at Risk?

One may also seek by using the **Am I at Risk?** flood tool provided by The Flood Hub. There, you can find who your Lead Local Flood Authority (LLFA) is and then go to the map and learn more about your flood risk. You can use this tool by entering your postcode and selecting your property.

Accessing flood maps online
Accessing flood maps online

Benefits of Flood Mapping in Planning

Flood mapping can provide many benefits for planning in the UK, such as:

Risk Mitigation

Flood maps are vital in identifying flood-prone regions. This information enables planners to plan for land use to ensure that they locate residential, commercial and critical facilities away from flood-prone zones. Community members should learn to avoid high-risk zones in order to minimise the possibility of flood damage.

Disaster Preparedness

Flood maps are invaluable for improving the preparation process for disasters. They assist in the formulation of good evacuation plans, early warning systems and emergency responses. As such, whenever floods happen, lives and properties are already protected.

Durability of Infrastructure

Flood mapping should form part of any infrastructure built for resistance to flooding. Therefore, roads, bridges, and buildings can be constructed using flood-resistant material coupled with elevation, minimising the expenses towards repairs following a flood.

Environmental Protection

The preservation of the environment is also enhanced through flood mapping in guiding sustainable land use. It helps to secure the natural life of wetlands and natural floodplains, which play a crucial role in sustaining local ecosystem balance against flooding.

Economic savings

Smart flood map planning is often more cost-effective in the long run. The financial cost of flood damage is reduced by avoiding flood-prone areas and using resilient construction practices that benefit both people and communities over a long period.

Future Trends in Flood Mapping and Planning

New technologies are emerging to make better flood maps and plans. Some of the future trends in flood mapping and planning in the UK are:

  • Utilising satellite data, LiDAR, and rainfall radar for the map’s high-resolution and higher accuracy. Advanced models, including probabilistic and dynamic ones, should also be applied.
  • Improving flood map accessibility and ease of use by creating web pages and interactive tools for different scenarios like different climate projections and land use change adaptations.
  • Reviewing the plans based on the latest evidence, stakeholders’ feedback, and policy changes every six years as per the Flood Risk Regulations 2009.
  • Natural flood management, sustainable drainage systems, property-level protection, community engagement, and emergency planning should be implemented to reduce flood risk.
  • Developing more all-encompassing flood maps illustrating multiple causes of flooding along with the effects of cascades and cumulative impacts.
  • Working with other countries, such as Scotland and Wales, to exchange best practices, data, and resources for flood mapping and planning across river basin districts and national boundaries.
Future trends in flood mapping
Future trends in flood mapping

Tips for Effective Planning Using Flood Maps

Here are some tips for effective planning using flood maps in the UK:

  • To know whether or not you need to carry out a flood risk assessment as part of a planning application, check the flood map for planning service on GOV.UK. You can also find printable flood maps containing your flood zone and obtain flood risk assessment data.
  • Check the latest flood warnings, alerts, and a five-day forecast on GOV.UK. Use the check for flooding service. You can also find your location’s river, sea, groundwater, and rainfall levels.
  • Navigate to our Maps, type your postcode, and you can see the flood risk that surrounds your postcode as well as neighbouring ones. Similarly, you can compare the flood risk with other regional postcodes.
  • Go to and view the extent of flooding risk at surface water. It will also inform you of how to read the map as well as its implications for you.
  • For information and advice on flood risk management and planning, contact the Environment Agency or your lead local flood authority. They will help you find a flood risk consultant, apply for planning permission, create a flood plan, and take action during a flood.

These tips will help you make the right choices and take mitigating actions for the risk of experiencing floods and their effects.


Besides, the flood map can help select reliable areas for establishing construction facilities, infrastructure, and disaster management service providers, as well as effective choices for mitigation, adaptation, and resilience. Hence, all planners should learn to read such maps to increase the standards of living, health, and sustainability in a community.

However, flood maps are critical during planning to ensure fewer adverse effects of floods. In addition, Urban Water’s flood risk assessment will meet your planning needs as required by relevant flood hazard regulations. Contact us today to discuss more on the project.

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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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