Flood Risk Map Dorset
| High | More than a 3.3% chance in each year (at least once in 30 years) |
| Medium | between 1%–3.3% chance each year (once in 100 to once in 30 years) |
| Low | between 0.1%–1% chance each year (once in 1,000 to once in 100 years) |
| Very Low | Less than a 0.1% chance each year (less than once in 1,000 years) |
Flood Risk Rivers and Sea
The Risk of Flooding from Rivers and the Sea (RoFRS) indicates the probability of flooding from rivers and the sea, incorporating the presence and maintenance of flood defences. While such defences can significantly reduce flood risk, they cannot remove it completely — overtopping or failure may still occur, which is why maps may show some level of risk even in areas that are protected.
Extent of Flooding
| High | more than a 3.3% chance of flooding in any year (at least 1 in 30) |
| Medium | between a 1% and 3.3% chance each year (between 1 in 100 and 1 in 30) |
| Low | between a 0.1% and 1% chance each year (between 1 in 1,000 and 1 in 100) |
| Very Low | less than a 0.1% chance each year (less than 1 in 1,000) |
Flood Risk Rivers and Sea - Planning
This planning map shows the risk of flooding from rivers and the sea. It was created by the Environment Agency to support with the flood risk assessments required for planning applications. Flood zones range from Flood Zone 1 (low risk) to Flood Zone 3 (high risk).
If your development is in a medium- or high-risk area, you will need a detailed, site-specific flood risk assessment. Get in touch with us to start your development process
Flood Zones
| Zone 1 (Low risk) | Less than a 0.1% chance each year (less than 1 in 1,000) |
| Zone 2 (Medium risk) | A 0.1%–1% chance from rivers (1 in 1,000 to 1 in 100) or 0.1%–0.5% from the sea (1 in 1,000 to 1 in 200) |
| Zone 3 (High risk) | More than a 1% chance from rivers (1 in 100 or greater) or more than a 0.5% chance from the sea (1 in 200 or greater) |
Flood Risk Surface Water
The Risk of Flooding from Surface Water (RoFSW) map illustrates where flooding could occur during heavy rainfall if water cannot soak into the ground or flow into drainage systems. In these conditions, rainwater may gather in low spots or move across the land surface. The map provides two key pieces of information:
- Flood extent – the area that could be affected
- Flood depth – how much water may accumulate
This national dataset is produced by the Environment Agency.
Extent of Flooding
| High | flooding could happen fairly often, with a chance of at least 1 in 30 each year (more than 3.3%) |
| Medium | flooding is less frequent, with a chance of between 1 in 100 and 1 in 30 each year (1% to 3.3%) |
| Low | flooding is unlikely but still possible, with a chance of between 1 in 1,000 and 1 in 100 each year (0.1% to 1%) |
Flood Risk Surface Water Planning
The Surface Water Spatial Planning datasets show areas that may be affected by flooding from surface water under present-day conditions. They combine the best available national and local flood modelling, including detailed information from Lead Local Flood Authorities where available. The datasets are intended to support planning decisions, site-specific Flood Risk Assessments and Sequential Tests by identifying areas that could be affected by surface water flooding from the 1 in 30, 1 in 100 and 1 in 1,000 annual probability events.
Extent of Flooding
| High | flooding could happen fairly often, with a chance of at least 1 in 30 each year (more than 3.3%) |
| Medium | flooding is less frequent, with a chance of between 1 in 100 and 1 in 30 each year (1% to 3.3%) |
| Low | flooding is unlikely but still possible, with a chance of between 1 in 1,000 and 1 in 100 each year (0.1% to 1%) |
Flood Risk Reservoirs
This is the maximum extent if a reservoir were to fail and release its water. This is the worst case scenario, it's unlikely that any actual flood would be this big. This data is intended for emergency planning services only.
Historic Flood Map
These are areas of land that have been previously flooded in England. It is possible that an area has been flooded but has not been recorded. This data does not indicate if a property has been flooded internally.
Historic Flood OutlineFlood Defences and Flood Storage
The Flood Defences datasets show the location of Environment Agency flood defence assets and water storage areas used to manage flood risk from rivers and the sea. Flood defences include embankments, walls, barriers and other structures designed to reduce the likelihood and impacts of flooding, while water storage areas temporarily store floodwater to reduce downstream flood peaks. These datasets provide an indication of flood risk management infrastructure and help users understand how flood risk may be managed in an area.
Environment Agency & Flood Models
This section shows Main Rivers, Environment Agency (EA) consultation areas and the extent of detailed flood models. These datasets can help identify developments that may require consultation with the Environment Agency and indicate where detailed flood modelling is available to support flood risk assessments and planning applications.
Flood Warning Areas
This map shows the areas where the Flood Warning Service is provided by the Environment Agency. We recommend you register to the service if your property is expected to flood from river or sea.
Flood Warning Areas5 Day Flood Forecast
The Flood Guidance Statement (FGS) is a 5-day risk-based product for England and Wales
- It is produced by the Flood Forecasting Centre (FFC)
- It shows the forecast level of flood risk for the coming 5 days for surface water, river, groundwater and coastal flooding
- It uses a detailed risk matrix approach, based on a combination of likelihoods and impacts
- It forecasts at a local authority scale
- It provides a summary forecast for the 6 to 10 day period where necessary
Overview
See user guide for more information
Forecast flood risk areas
Flood Risk Solutions
We need to adapt our way to live and learn to live with flooding. We can limit the impact of flooding by working together at a development, community and house level. These are some initiatives that you can start applying.
Green infrastructure is a cost-effective and sustainable flood management approach that gathers and removes water at its source.
Use green roofs to soakaways. Make them part of the landscape. This will reduce their costs and increase the quality of your development.
Re-use rainwater for the irrigation of plants, gardens and also within buildings. Design your development with temperate climate areas in which water is used.
It is easy to forget that flood water can be part of the development. Although we can protect individual dwellings from flooding, we can also make the external areas enjoyable and part of the flood zone.
Zero carbon will reduce climate change and in turn the risk and impact of future flooding.
Coastal Erosion
The Coastal Erosion Risk datasets show areas that may be affected by future coastal erosion and shoreline change. The maps are based on the Environment Agency's National Coastal Erosion Risk Mapping (NCERM) and provide projections for different time periods, management approaches and climate change scenarios. They are intended to support planning, development and long-term land management decisions.
| Ground Instability Zone | Ground Instability Zones identify areas of geologically complex coastline where previous cliff movement, landslides or ground instability have occurred. The mapped extent includes areas that may be vulnerable to future ground movement over the next 100 years. |
| Ground Instability Recession | Ground Instability Recession shows the potential landward extent of future cliff recession and ground movement. The dataset helps identify areas where coastal instability may affect land and development over the long term. |
