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London Flood Risk Map - Guide for 2023

London flood risk map provides information for mitigation, emergency and planning. The flood map can be found on the  Environment Agency website and in the local boroughs’ pages. 

London flood risk maps are the basis for managing risk. Flood maps evaluate the risks to any proposed development.

This article includes

Information regarding London flood maps.

Sites to access strategic flood risk assessment reports for all London boroughs

Information about flood zones

Current London flood risk maps

Thames Estuary 2100 plan

Key Maps

This is a complete guide for London flood risk maps. 

We have all the flood level information for the river Thames in London. 

In this chapter, you will find links to strategic flood risk assessment reports flood risk maps of all London boroughs. 

Let’s get started 

Finding information on flood risk maps

The Environment Agency Flood Risk Map is the most important for planning and long-term flood risk.  We have created our  Comprehensive flood risk map with all the Environment Agency information in one place.

We have the flood level of the river Thames. Send us an email if you need this information. 

We have gathered data to access Strategic Flood Risk Assessment and Flood risk maps for all the major Boroughs of London. 

To see the SFRA of any borough of your interest, just google “strategic flood risk assessment” and add the name of your council. 

Climate Change Adaptation Map

The section guides you about climate change adaptation maps.

London climate risk adaptation map displays information about risks and vulnerability to climate change across Greater London.

The map is there to help the Mayor and London-based organizations to allocate resources to the most vulnerable communities towards climate change.

In this section, you will find  information and maps of 

  1.  Climate Risk and Vulnerability
  2. Greater London Green Infrastructure
  3. Urban Heat Island Map
  4. London Sustainable Drainage Systems Case Studies Map
  5. Nature Based Solutions

Climate Risk and Vulnerability

Climate vulnerability identifies people who are exposed to the effects of climate change, i.e., flooding or heat waves; it also takes into account the capacity of people to respond to such changes and their ability to cope. The city-wide map utilises different metrics to identify areas with high exposure to climate risks and the concentration of the most vulnerable populations in different areas. The climate risk maps help the Major address climate risks and resource allocation to vulnerable segments of society.

Guidelines to view the maps

London climate risk maps provide information on flood risk, overall risk, and heat risk. The maps are used in combination with individual metrics to determine flood risk.

In the map, the left side displays risk maps of selected areas. The right side of the slider shows information about environmental exposure or social vulnerability metrics. On the right corner layer list will allow you to customise information.

Use the eye icon to select one or more options from the layer you want to see, and the slider tool will allow you to compare the information.

Follow the instructions below

london flood risk map
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Pictures Source: London Climate Risk App

Greater London Green Infrastructure

London’s Green infrastructure map aims to provide individuals and organisations with information to understand and improve London’s green infrastructure.

The map provides a baseline to help monitor London environmental agency targets. In addition, the data provides context for decision-makers regarding protecting, creating, or improving green infrastructure.

The map shows how many areas of London are covered by trees, and open waters, using land mapping and high-resolution aerial imagery. The map’s representation of green cover and water spaces is not limited to parks. For example, it shows trees in private gardens, green roofs, and road verges.

london green infrastructure map 1.png

Picture Source: London Green Infrastrucure

Urban Heat Island Map

The urban heat island map shows the results of a simulation for the average temperature at midnight. For this map, summer 2011 from May to September was selected, as it represents usual summer conditions, i.e., a summer that is not too hot or cool. The map shows that in the city centre, the temperature is approximately four °C higher due to Urban Heat Island. 

The temperature can even increase during hot summer nights. It can have severe health implications for vulnerable groups, i.e., the elderly or babies. The map illustrates one of the many consequences of climate change. Improving existing green infrastructure can help eliminate the urban heat island.

urban heat island map 1.png

Summer 2011: Mid-Night Mean Temperature

London Sustainable Drainage System (SuDS) Case Study Map

London sustainable drainage map shows the locations of known sustainable drainage SuDS projects across the city. The SuDS are vital as they help the city in climate change adaptations. SuDS can have a contributing role in greening the city.

Through this map, the public members and the stakeholders keep updating the residences about new additions to SuDS schemes across the city. It gives an idea about the pace of changes across the city and the capability of surface-water flood resilience in London.

Multiple colour dots on the map below represent different SuDS sites. Click on the dots in the map, which will provide detailed information about the project.

london sustainable drainage system suds 1.png

Picture source:SuDS site maps

Nature Based Solutions

We have put together a map showing the government’s Latest Project on nature-based solutions. The map also shows the Floodplain Reconnection Areas, Runoff Attenuation, Woodland Planting and infiltration Areas

Understanding flood zones and London Flood risk map

The Environment Agency uses flood zones as a guidance tool to demonstrate the probability of flooding occurrences in any area across London because of river and sea flooding.

This section will teach you about flood zones and London flood risk maps. The environment agency provides London flood risk maps and identifies zones according to the severity of flood risks.  

  1. Flood Zone 1: Low probability
  2. Flood Zone 2: Medium Probability 
  3. Flood Zone 3a: High Probability
  4. Flood Zone 3b: The functional probability

Flood Zones Overview

Flood zones provide information to developers, communities, and relevant agencies to understand the presence of flood risks in any specific location, keeping the existence of flood defence systems in consideration. Although flood zones are indicators, they cannot provide precise information on whether any site will certainly be under flood and the severity of such flooding. 

The environment agency provides London flood risk maps and identifies flood zones on the map. 

Flood Zone 1: Low probability

Areas with a low probability of flooding are categorised as flood zone 1. In zone 1, the likelihood of river and sea flooding is less than 0.1% per annum. Zone 1 can also be described as lands with a 1 in 1,000 probability of having river and sea flooding.

As shown on our flood zone map,  zone 1 is all the land outside zones 2 and 3.

Flood zone 2: Medium Probability

Areas with a medium probability of flooding are categorised as flood zone 2. In zone 1, the possibility of river flooding is 1.0% and 0.1% per annum. The probability of sea flooding is 0.5% and 0.1% per annum. Zone 1 can also be described as lands between 1 in 100 and 1 in 1,000 likelihood of river flooding in a year. 

On our flood zone map,  zone 2 is shown in light blue colour.

Flood zone 3a: High probability

The flood zone is divided into two sections, namely, 3a and 3b. Flood zone 3a are the areas with a higher than 1% probability of flooding from river sources or greater than 0.5% probability of flooding from the sea. Zone 3a is defined as the land with a 1 in 100 likelihood or more of river flooding in a year and the probability of sea flooding 1 in 200 or more in a year.

On our flood zone map, zone 3a is shown in dark blue.

Flood zone 3b: The Functional Floodplain

Flood zone 3b is also named the functional floodplain. Flood zone 3b includes land that either accumulates water during flooding from sea and river or allows water to flow through during flood periods.

Zone 3b is the land with a 3% or greater probability or more of flooding in a year, regardless of the flood risk management system in place. Flood Zone 3b also refers to land that is ‘designed to flood’, which defines a land that might only experience flooding during severe weather conditions.

 On the flood zone map, zone 3b is not separately distinguished from 3a.

Current London Flood risk map and what do they tell you

The section highlights recent studies on flood risks due to climate change. 

It also includes a map showing the extent of flood risks in different areas of London. 

Another map highlights the probability of future surface water floods. 

The section also incorporates information on risk to individual properties. 

London city flood risks

A map compiled by London’s City Hall and Bloomberg Associates shows 19 of the 28 opportunity areas contain zones vulnerable to floods. The map was developed by taking into account the rainfall patterns together with 16 various metrics that impact residents’ ability to deal with flooding. That includes the socio-economic status of residents and the capacity to understand flood risk warnings in English.

Over the past two decades, the frequency of torrential rains has increased in London in fall and winter. According to U.K. Met Office experts, this frequency is likely to increase over the course of the century. By 2070 U.K. is expected to experience a doubling of extreme rainfall

london city flood vulnerability 1.png

Picture source: Environment Agency

How to find if an individual property is at risk of flooding

Information on flood risk in a locality can be accessed through Environment Agency’s flood map for planning by entering the postcode. The map allows you to enter a postcode and see long-term flood risk in your interest. However, it must be noted that the Environment Agency flood risk map does not consider future flood risks due to climate change.

If you are worried about flood risks to your site or planning a development, the flood risk maps can provide you with an overall idea of flood risk in your area. In addition, we provide flood risk assessment for planning applications  if you are looking for a site assessment report. Our site-specific Flood risk assessment assesses all flood sources. The flood risk assessment complies with all flood risk legislation.

Our flood risk interventions safeguard your site from flooding.

The Environment Agency and local planning authorities approve our detailed flood risk assessments. Therefore, we use the most reliable data.

We have a blog that gives detailed guidelines for Flood Risk Assessments (FRAs) and the Sequential and Exception test.

Thames Estuary 2100 Plan​

The section explains the Thames Estuary 2100 plan. 

To develop a strategic flood risk management plan for London and Thames estuary, the Environment Agency established Thames Estuary 2100 project in 2002.

Let’s have a look at the main aims of the TE2100.

Thames Estuary 2100 Plan

The plan mainly looks at tidal flooding. However, flooding from other sources, i.e., surface-level flooding and heavy rainfalls, is considered.

The plan aims to provide a strategic flood risk management plan for the century. The plan was developed to provide flood risk management strategies to ensure the safety of people and properties in floodplains. Climate change will likely increase the tidal flood risks for people and properties in floodplains. In addition, there was also an acknowledgement of the fact that the existing flood walls, barriers, and embankments are getting older and would need to be improved or replaced to handle the change in water levels.

The plan proposes actions and recommendations that must be implemented to manage flood risks throughout the century. Before developing the project, an in-depth investigation of current flood risks in the Estuary was carried out, and the probabilities of changes in future due to climate change. The plan also explores and recommends ways to deal with such changes.

The Thames estuary – tidal flood risk today

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Picture source: Thames Estuary 2100 Plan

The plan outlines that climate change, ageing flood risk, and population growth will increase flood risks, which requires a proper management system. The Thames Estuary 2100 Plan aims to protect 1.42 million people, vital infrastructure, and properties worth 312 billion pounds from tidal flood risks.

Frequently Asked Questions​

Let’s answer all some of your questions

What areas in London are vulnerable to flooding?

The areas more vulnerable to flooding from Rivers and Sea are those located after the Thames Barrier and along the smaller watercourses leading to the Thames.

Where does it flood the most in London?

Based on the information from Dec 1, 2019.  The Boroughs that have the most properties at High to Low risk are  Newham London Borough with 22,381 properties, followed by Enfield London Borough with 13,019 properties.

Which boroughs are at high risk of flooding in London?

The Boroughs that have more properties at risk of high and medium risk are Kingston upon Thames London Borough and Croydon London Borough.
See the table below:

London Areas more at risk of flooding.jpg

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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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