Flood Risk Assessment

What is a flood risk assessment?

Also known as an FRA, a flood risk assessment is a key part of the site assessment and planning submission process and is required by the Local Planning Authority if the development will be situated in flood zones 2 or 3, in an area of one hectare or more in flood zone 1, is located within a critical drainage area or on a site where there is a risk of surface water flooding. 

The main objectives of flood risk assessments are: 

• assessing the risk and impact of flooding on the site.
• determining whether the proposed development will affect flooding in the local area. 
• to determine and recommend how the risk of flooding can be mitigated in the development site. 
• to demonstrate that the site will be safe in the present and future, taking into account the development’s vulnerabilities and the impact of climate change. 

What should a flood risk assessment include? 

A good flood risk assessment will reveal whether a development can be constructed on a site by determining whether the area lies in a flood zone and assessing the proposed site’s topography. 

Fundamentally, the assessment will provide a detailed analysis of available data on the site’s flood risk and will produce recommendations for flood mitigation actions. 

The assessment will equally demonstrate consideration of flooding from all possible sources which include: 

• Pluvial (surface water from rainfall)
• Fluvial (river flooding) 
• Groundwater
• Estuary and coastal 
• Sewer flooding

How long does a flood risk assessment take?

Our lowest tier of GeoSmart flood risk assessment is FloodSmart which is suitable for sites within a flood zone 1, sites which are larger than 1 hectare, critical drainage areas and sites with a high risk of surface water flooding. 

This type of flood risk report can be delivered within 5-10 working days. 

Our FloodSmart Plus and Floodsmart Pro reports are suitable for sites located in flood zones 2 and 3 and can be delivered within 20-30 working days. 

We are required to request data from the Environment Agency which can take up to 20 working days to be provided. 

Who are flood risk assessments for? 

Flood risk assessments are intended for: 

• house builders and developers.
• property professionals such as architects, planning consultants and land agents.
• lawyers and solicitors.
• lenders, banks or mortgage providers.
• businesses.
• private individuals.
• insurance companies.

Is a flood risk assessment always required?

According to government guidance, flood risk assessments need to be undertaken if developments are located within flood zones 2, 3 or 3b, if the site is more than one hectare and sits within flood zone 1 or situated in flood zone 1 area that will be at risk of river or sea flooding in the future, as determined by the Local Planning Authority’s SFRA (Strategic flood risk assessment). 

In addition, an FRA will also be required if the development is situated in an area with critical drainage issues or has been shown by the Local Planning Authority to have a high vulnerability classification.  

For the Welsh and Scottish flood risk maps, similar guidance applies. 

In Wales, the Natural Resources website Wales provides a similar service to the English government where users can input a home or development site postcode to reveal the flood risk status. 

Flood consequence assessments (FRC) are the alternative to FRAs in Wales as are the country’s flood zones which are based on the Development Advice Map (DAM). 

In Scotland, according to section 42 of the Flood Risk Management (Scotland) Act 2009, flood risk assessments are required “where the application relates to a development that is likely to result in a material increase in the number of buildings at risk of being damaged by flooding.”

The Scottish Environment Protection Agency (SEPA) contains more information surrounding flood risk. 

Do I need a flood risk assessment?

Aside from being required by the Local Planning Authority, FRAs are an important aspect of flood risk management to reduce the associated threats posed to humans and the environment. 

Additionally, FRAs work to decrease the frequency of human and socio-economic losses. 

What are the different flood zones in England?

Flood zones describe the areas in England which, to varying degrees, are more susceptible to flooding. 

Created by the Environment Agency, the English flood risk map determines the different zones through various colours and will highlight which zone the postcode area you have inputted belongs to. 

It is an essential tool for any flood risk consultant needing to provide flood risk assessment guidance.  

The different flood zones are outline as follows: 

• Flood zone 1: Land in this area has a low probability – less than 1 in 1000 chance – of being flooded by river or sea.  
• Flood zone 2: Land in this area (highlighted in light blue) has a medium probability of flooding – the likelihood of river flooding happening per year is between 1 in 100 and 1 in 1,000 or between 1 in 200 and 1 in 1,000 for sea flooding. 
• Flood zone 3a: Land in this area (shown in dark blue) has a high probability of flooding – the chances of  river flooding is between 1 in 100 or greater and 1 in 200 for sea flooding. 
• Flood zone 3b: Land in this area (also shown in dark blue) is predicted to be filled with water when a nearby river floods.