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Enhancing flood modelling guidance for streamlined planning approvals

By Simon Lewis, Senior Technical Advisor, Environment Agency

Over the last few years, our flood modelling teams in the Environment Agency have worked with Jacobs and the wider flood modelling community to develop and publish flood modelling standards. These standards which cover fluvial and open coast and estuaries were developed to help improve the quality of the flood models we see as clients and to benefit the wider flood modelling community.

In December 2023, our flood modelling teams published a new guidance to complement the existing standards specifically aimed at those using flood modelling as part of the planning process.

The guidance can be found here: Using modelling for flood risk assessments 

In our role as a statutory consultee, the Environment Agency comments on about 110,000 land use planning applications a year, and predominantly we comment on flood risk. In 2022-23, 99% of new homes in planning applications, and 96% of all planning decisions overall complied with Environment Agency advice.  But getting to that point can sometimes be fraught on all sides. Our new guidance is there to help improve the experience for all involved by helping set clear expectations for flood modelling.

Stock image of residential development site

The guidance is for anyone (planning applicants, developers, and consultants) who uses modelling in flood risk assessments (FRAs) when applying for planning permission. It touches on how to use hydrological and hydraulic modelling as part of a flood risk assessment for a planning application, and the expected standards.  For me, one of the clearest points our guidance makes is, if you submit a model to us (in a planning application) you are responsible for everything in it, even if that model was originally supplied to you by us, or another Risk Management Authority (RMA). In England, there are many sources of existing flood models that anyone can access. The Environment Agency has thousands of models that you can request, and more are available from other RMAs. It is up to the planning applicant, often via their consultant, to demonstrate their modelling is fit for purpose when they submit it in support of their application. So, if you are reusing and modifying someone else’s model not only will you have to update your site-specific details but also make sure all the rest of the model is to the latest/appropriate standards and representative of the current situation.

For me, the other key point from the guidance is, quality assure your model thoroughly. Picking up issues early before submission will save you so much time and effort.

Following our guidance, “Using modelling for Flood Risk Assessments”, should help anyone submitting a model as part of a planning application by:

  • Reducing the challenges to your modelling

  • Reducing the time it takes regulators to review your model (and respond overall to your planning application)

  • Increasing the overall quality of your model and the confidence in the story it tells about flood risk pre- and post-development for your site (and the benefits your planning application brings).


As understanding and mitigating flood risk becomes increasingly necessary to safeguard communities and become more resilient, it is paramount to equip professionals with innovative, yet accessible, solutions to empower them to address the challenges ahead.

Watch our webinar where we use a real-life example to demonstrate how Flood Modeller can be used to build, run, and analyse a model quickly and easily to support flood risk assessments, challenge flood maps and much more.


Picture of Simon Lewis

Simon Lewis is a Senior Technical Advisor in the Environment Agency.  He has 19 years’ experience in Flood and Coastal Risk management mostly focused on non-real-time modelling. Simon has a strong passion for enabling technology and innovation that enhances and improves how flood modelling is carried out with in the Environment Agency and the wider flood modelling community.


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