Floodplain
A floodplain is land adjacent to a watercourse over which water flows or would flow in times of flood, if defences were not in place.
The flood zone area classification system devised by the Environment Agency refers to:
- Flood Zone 1: Land outside the floodplain. There is little or no risk of flooding in this zone.
- Flood Zone 2: The area of the floodplain where there is a low to medium flood risk.
- Flood Zone 3: The area of the floodplain where there is a high risk of flooding.
Ref The HS2 London-West Midlands Environmental Statement, Department for Transport, November 2013.
NB Culvert, screen and outfall manual, (CIRIA C786) published by CIRIA in 2019, defines a floodplain as: ‘Land on either side of a river that is below the highest defined flood level.’
The National Flood and Coastal Erosion Risk Management Strategy for England, Glossary, published by the Environment Agency in 2020, suggests a floodplain is: ‘Land with a high probability of being partly or wholly covered with water during flooding from rivers or the sea – ignoring the presence of flood defences.’
[edit] Related articles on Designing Buildings
- Applying flood resilience technologies GG 84.
- Building flood resilience.
- Catchment flood management plans.
- Coastal defences.
- Dyke.
- Environment Agency.
- Flood.
- Flood and Water Management Act.
- Flood defences.
- Flood insurance.
- Flood mapping key to future development in Wales.
- Flood risk.
- Flood risk assessment.
- Flood risk management plans.
- Floodplain capacity.
- Floodscape.
- Functional floodplain.
- Future flood prevention.
- Pitt Review.
- River engineering.
- Sustainable urban drainage systems.
- Thames barrier.
- Water engineering.
Featured articles and news
Buildings that changed the future of architecture. Book review.
The Sustainability Pathfinder© Handbook
Built environment agency launches free Pathfinder© tool to help businesses progress sustainability strategies.
Government outcome to the late payment consultation, ECA reacts.
IHBC 2025 Gus Astley Student Award winners
Work on the role of hewing in UK historic conservation a win for Jack Parker of Oxford Brookes University.
Future Homes Building Standards and plug-in solar
Parts F and L amendments, the availability of solar panels and industry responses.
How later living housing can help solve the housing crisis
Unlocking homes, unlocking lives.
Preparing safety case reports for HRBs under the BSA
A new practical guide to preparing structural inputs for safety cases and safety case reports published by IStructE.
Male construction workers and prostate cancer
CIOB and Prostate Cancer UK encourage awareness of prostate cancer risks, and what to do about it.
The changed R&D tax landscape for Architects
Specialist gives a recap on tax changes for Research and Development, via the ACA newsletter.
Structured product data as a competitive advantage
NBS explain why accessible product data that works across digital systems is key.
Welsh retrofit workforce assessment
Welsh Government report confirms Wales faces major electrical skills shortage, warns ECA.
A now architectural practice looks back at its concept project for a sustainable oceanic settlement 25 years on.
Copyright and Artificial Intelligence
Government report and back track on copyright opt out for AI training but no clear preferred alternative as yet.
Embedding AI tools into architectural education
Beyond the render: LMU share how student led research is shaping the future of visualisation workflows.
Why document control still fails UK construction projects
A Chartered Quantity Surveyor explains what needs to change and how.
Inspiration for a new 2026 wave of Irish construction professionals.
New planning reforms and Warm Homes Bill
Take centre stage at UK Construction Week London.