Challenging Flood Maps

May 21, 2021

The flood zone in which land sits can be a major hurdle for many new developments.


Flood maps published by the Environment Agency, SEPA and NRW, place land into different categories depending on how likely it is to flood. These categories are based on national datasets and, unless local evaluation and mapping has been undertaken, they are unlikely to have been reviewed in detail. There are many cases where flood maps overstate the risk of flooding and as a result, limitations are unnecessarily placed on development. There are also cases where the flood maps underrepresent the risk, which can result in unexpected issues and even fatal flaws being raised during the planning process, often by third parties or objectors.

The flood maps do not have to be taken at face value and developers can challenge them.


It is important to understand the real risk of flooding and the potential limitations it may impose on your development early in the evaluation and planning process. By confirming the accuracy of the published maps, the true viability of your development can be assessed from a flood risk perspective.


Seeking the expert advice of a specialist at project inception will determine one of three outcomes:


(1)   the flood maps are correct and provide an accurate assessment of flood risk;

(2)   they are incorrect and in fact the site is at a lower risk than is mapped; or

(3)   that the flood maps are incorrect and in fact the site is at a higher risk than is mapped.


While the last outcome is not desirable, identifying this can prevent unexpected and costly delays during a planning application process, or investment in land that is unsuitable to be developed for the intended use.


If flood maps show land to be at a higher risk of flooding than it should be, then this offers an opportunity for developers to challenge the maps and release the development potential.


Our specialists are seeing more and more instances where flood maps are incorrect and indicate that the flood risk is greater than is the case. Challenging the status quo can be done by either lodging a query with the regulator to re-classify the published map or submit sufficient evidence with your planning application to demonstrate the correct flood risk. Depending on the nature of the development, our experts will advise you on the best course of action to achieve success.


In our experience, challenging published maps is an option that is often overlooked, or considered too complex to undertake. It is true that in some cases the process can be complex, and may involve detailed hydrological reviews, acquisition of high-resolution survey data and even numerical modelling of channels and flood plains. That is why it’s important to identify the level of technical work required to address the issue and ensure this is proportionate to the scale of the proposed development.


Our specialists are experienced at challenging the regulators. We have successfully re-classified published flood maps or shown that sites are not at the risk indicated by the maps. We have won our clients’ battles with Lead Local Flood Authorities and obtained successful planning outcomes.


Could we help you? Contact our technical lead LeeClarke@envireauwater.co.uk or call 01332 871 882 to discuss the solution to your flood risk problem.

Share

Richmond Bike Park Success

By Rachael Plant • September 25, 2025
Envireau Water are thrilled to have contributed to the recent successful planning application for the construction of a community bike park in Richmond, North Yorkshire. Louise Raine, a local to the area, first set up the campaign after realising there were no 'safe and purpose-built spaces' for her children and other families. In collaboration with the local community and town council, Envireau Water volunteered to provide high-level technical support on flood risk and drainage solutions, following concerns raised by a lead regulatory authority. Hydrologists, Mairi , Lee , and Michael conducted a review of flood risk, drainage pathways and soil infiltration potential. Upon developing the drainage strategy and producing pre- and post-development 2D runoff modelling, it was discovered that the proposed location had no significant risk. By investigating the soil types and overland flow pathways, it was also noted that the suggested drainage strategy would have both a flood risk benefit and an environmental benefit of enhancing the ecology and biodiversity of the land.

Anna Hitchmough joins Envireau Water

By Rachael Plant • July 22, 2025
We are excited to welcome Dr Anna Hitchmough to our growing team, who recently joined Envireau Water as a Principal Technical Specialist. With over 25 years of consultancy experience in hydrogeology, Anna brings a wealth of expertise to our team. Anna joins us from Carbon Zero Consulting/RSK Geosciences, where her career has centred around ground-source heat pump systems. In her most recent role, Anna chaired RSK's Heat Decarbonisation Working Group and Hydrogeology Working Group. Anna brings extensive experience in quantitative risk assessments and NAPL characterisation and has completed significant work on several contaminated land projects, having previously served as Chair of the Geological Society's Contaminated Land Group. Anna's academic background stems from the University of Newcastle where she completed an MSc in Hydrology, followed by a PhD in Hydrogeology at the University of Birmingham. She is also a chartered geologist.

Hannah Muir joins Envireau Water

By Rachael Plant • July 10, 2025
We're always excited to see our team grow, and we are thrilled to welcome Hannah to the team. Hannah joined our Scotland office at the end of June to gain some hydrogeological experience alongside completing her university studies, and we look forward to welcoming her officially in September where she will begin her career as a Hydrogeologist. Prior to joining, Hannah completed a BSc in Environmental Sciences at University of Glasgow and is currently working towards completing an MSc in Hydrogeology at the University of Strathclyde. During her masters and undergraduate degree, Hannah has participated in various fieldwork activities where she developed an in-depth understanding of applied hydrology, soil analysis and mapping techniques.
Show More

Richmond Bike Park Success

By Rachael Plant • September 25, 2025
Envireau Water are thrilled to have contributed to the recent successful planning application for the construction of a community bike park in Richmond, North Yorkshire. Louise Raine, a local to the area, first set up the campaign after realising there were no 'safe and purpose-built spaces' for her children and other families. In collaboration with the local community and town council, Envireau Water volunteered to provide high-level technical support on flood risk and drainage solutions, following concerns raised by a lead regulatory authority. Hydrologists, Mairi , Lee , and Michael conducted a review of flood risk, drainage pathways and soil infiltration potential. Upon developing the drainage strategy and producing pre- and post-development 2D runoff modelling, it was discovered that the proposed location had no significant risk. By investigating the soil types and overland flow pathways, it was also noted that the suggested drainage strategy would have both a flood risk benefit and an environmental benefit of enhancing the ecology and biodiversity of the land.

Anna Hitchmough joins Envireau Water

By Rachael Plant • July 22, 2025
We are excited to welcome Dr Anna Hitchmough to our growing team, who recently joined Envireau Water as a Principal Technical Specialist. With over 25 years of consultancy experience in hydrogeology, Anna brings a wealth of expertise to our team. Anna joins us from Carbon Zero Consulting/RSK Geosciences, where her career has centred around ground-source heat pump systems. In her most recent role, Anna chaired RSK's Heat Decarbonisation Working Group and Hydrogeology Working Group. Anna brings extensive experience in quantitative risk assessments and NAPL characterisation and has completed significant work on several contaminated land projects, having previously served as Chair of the Geological Society's Contaminated Land Group. Anna's academic background stems from the University of Newcastle where she completed an MSc in Hydrology, followed by a PhD in Hydrogeology at the University of Birmingham. She is also a chartered geologist.

Hannah Muir joins Envireau Water

By Rachael Plant • July 10, 2025
We're always excited to see our team grow, and we are thrilled to welcome Hannah to the team. Hannah joined our Scotland office at the end of June to gain some hydrogeological experience alongside completing her university studies, and we look forward to welcoming her officially in September where she will begin her career as a Hydrogeologist. Prior to joining, Hannah completed a BSc in Environmental Sciences at University of Glasgow and is currently working towards completing an MSc in Hydrogeology at the University of Strathclyde. During her masters and undergraduate degree, Hannah has participated in various fieldwork activities where she developed an in-depth understanding of applied hydrology, soil analysis and mapping techniques.

Rob Pickersgill joins Envireau Water

By Rachael Plant • July 8, 2025
Our team just keeps on growing and we are delighted to welcome Rob Pickersgill as our newest member! Rob joined us at the end of June, bringing extensive experience across both hydrology and civil engineering, with a particular focus on hydraulic modelling, Flood Risk Assessments (FRAs), and Discharge Impact Assessments. Rob's academic background stems from the University of Nottingham, where he completed a MEng in Engineering, followed by an MSC in Global Urban Development and Planning at the University of Manchester. Rob joins our specialist surface water team and will be based at the RSK Group office in Bristol, providing hydrological services to a range of projects for our diverse client base, primarily within the development sector.
Show More