Why has my Flood Risk Assessment been rejected?
Tips for early approval
6-minute reading time
Written by Nathan Montgomery, Project Consultant
For planning applications across England, Scotland and Wales, flood risk assessments (FRAs) (England and Scotland) and flood consequence assessments (FCAs) (Wales) are used to ensure that developments and their inhabitants are safe from flooding throughout their lifetime. Far too often, we review assessments that contain common pitfalls which lead to unnecessary delays, rising costs and damaged relationships.
In this post, we’ll be looking at why a flood risk assessment might be rejected by a local authority and ways to boost your chances of approval first-time.
- Missing data
An accurate FRA is underpinned by accurate and complete data from all sources of flooding. Where this data is erroneous or, in some cases, omitted, this can cause needless delays to your projects. An example we see often is a basic flood risk assessment, clearly stating the Site is in Flood Zone 3 with no other context provided. Detailed hydrological modelling is the foundation for the flood zone classification, and the Environment Agency (EA), Natural Resources Wales (NRW) or Scottish Environment Protection Agency’s (SEPA) model data should be requested right away, as this provides insightful data which can improve your chances of approval.
Rather than simply stating the flood zone classification, GeoSmart use detailed modelling to confirm the depth, velocity and extent of flooding throughout several modelled scenarios. This detailed model could massively improve the chances of approval, as it includes both defended and undefended scenarios, which could show your property at a much lower risk than the flood zones suggest. Where there is an increased risk of flooding, the depth data allows us to suggest appropriate and proportionate mitigation measures to ensure your development is safe throughout its lifetime, clearly demonstrating that the relevant local and national policy has been considered in line with the flood risk at the Site, boosting the chance of approval.
- Not considering Climate Change
The evidence is overwhelming – our planet is changing at a rate never seen before, and we need to be prepared for a warming world. The latest EA data identifies that 1 in 4 properties in the UK are at risk of flooding from any source. Whether you are a developer in England, Wales or Scotland, the national and local policy is clear: climate change consideration is a necessity in flood risk assessments. It is so important that the future climate change events are commonly known as the ‘design’ flood event, which is the event new developments must be prepared for.
So why are we seeing so many FRAs only considering the present day? For all sources of flooding, the future risk to the development has to be considered. The allowance needs to be proportionate to the level of risk, source of flooding and type of development. For example, coastal sea walls might protect your seaside view property now, but with rapid sea level rise expected over the next 100 years, how will that risk change for a family home by the coast in the 2120s? How will an outdated commercial drainage network cope with increasingly intensifying and unpredictable rainfall patterns?
Where the design flood event is not considered or is not appropriate, local authorities have an easy decision to make. A GeoSmart FloodSmart report ensures that climate change is assessed as a priority, including clear guidance on why this allowance has been chosen.
- Insufficient mitigation
Whilst a flood risk assessment should provide concise information regarding the potential risks, many FRAs receive objections from the local authority due to a lack of mitigation measures, keeping property resilient and people safe throughout the development lifetime. Local authorities are consistently looking for more evidence of measures that will be incorporated into the development.
Whether that’s raised finished floor levels, a new sump and pump system to get floodwater out fast or waterproof tanking for a new basement level, FRAs need to provide clear and proportionate mitigation measures that reduce the likelihood of flooding and its impact and improve recoverability in the event of a flood.
- Not considering flood risk elsewhere
Whilst a flood risk assessment is site-specific, it needs consideration of how the proposed development will affect the surrounding areas. The most common omission from FRAs which trigger an objection is the lack of discussion regarding floodplain compensation. A new development in the floodplain will displace floodwater, moving it elsewhere and potentially increasing the risk for others. Where this is not acknowledged, the EA/NRW/SEPA and Lead Local Flood Authorities (LLFAs) are quite rightly going to have concern regarding the surrounding areas.
This links back to our consideration of climate change, as development must make sure there is no displacement of flooding during a ‘design’ flood event (a 1 in 100 year event with an allowance for climate change). Our FloodSmart reports provide clear background which identifies if floodplain compensation will be required, and our consultants are happy to discuss potential next steps to ensure the best chance of success.
- A weak groundwater assessment
A flood risk assessment should assess all sources of flooding, and a regularly forgotten source of flooding is the hidden risk of groundwater. With the potential to last substantially longer than other sources, groundwater flooding has the potential to cause significant disruption and damage to properties, yet its consideration in flood risk assessments is often an afterthought, leading to queries and delays in several planning applications.
Particularly prominent in basement developments, the risk of groundwater is increased and needs to be considered. Our GW5 mapping included in a GeoSmart FloodSmart report provides an excellent screening risk, outlining the risk of groundwater emergence during a 1 in 100-year event. Our experienced consultants use this screening assessment to understand the potential of groundwater flooding at the Site, providing a holistic understanding of the hydrogeological characteristics which influence the risk of groundwater, including geology and proximity to watercourses.
- Ignoring local policy
Whilst most guidance is national, including the National Planning Policy Framework and guidance (NPPF & NPPG), TAN15 (Wales) and National Planning Framework 4 (Scotland), local policy is an important factor to consider when completing a flood risk assessment. Local Development Plans and Strategic Flood Risk Assessments (SFRAs) are produced by local authorities, which could provide more stringent guidance or specific policy which needs to be adhered to in areas of higher risk.
Councils will judge development proposals on specific flood risk guidance in line with their development policies, so it’s crucial that FRAs review these documents, as local guidance can vary significantly across the UK.
Summary
With so many potential pitfalls, it’s crucial that careful consideration is taken when purchasing a flood risk assessment. These tips can help you avoid common errors, which in turn speeds up the planning process, allowing for early approval and reduced costs.
Our technical team of consultants are happy to discuss our services, consistently aiming for first-time approval.
GeoSmart Information Ltd (Technical Advisors)
enquiries@geosmartinfo.co.uk
01743 298 100
www.geosmartinfo.co.uk
