Leeds Flood Alleviation Scheme Phase 1 (FAS 1)
Leeds City Centre, from Leeds Station to Woodlesford, UK · Completed in 2017 (started after December 2015 floods) · Part of a £200 million project for both phases.
The judgement call
Account-gated at launchThe scheme was a direct response to the devastating 2015 Boxing Day floods. - The use of movable weirs allowed for flexible flood management. - Phase 1 has been activated nine times since its completion, demonstrating its effectiveness and the increasing frequency of extreme weather events.
Key engineering challenges
Protecting a major city centre from extreme flooding events (River Aire reaching highest ever level of 5.2m with 360 tonnes of water per second). - Integrating new flood defences with existing urban infrastructure and maintaining waterfront access. - Implementing innovative movable weir technology, the first of its kind in the UK, to create temporary storage in the river channel.
Project facts
- Client / owner
- Leeds City Council, Environment Agency, West Yorkshire Combined Authority (WYCA)
- Lead contractor
- —
- Lead designers
- —
- Project type
- new build | upgrade
- Scale
- Protects 4000 homes, 1000 businesses, and safeguards 33,000 jobs to a 1-in-200-year standard of protection. Involved merging the River Aire and canal at Knostrop Cut, building new walls and embankments, and using two innovative movable weirs at Knostrop and Crown Point.
- Disciplines
- civil; hydraulic; environmental
- Standards & frameworks
- 1-in-200-year standard of protection plus climate change allowance.
Sources: "Ten years on: How devastating floods led to a more resilient city", Leeds Climate Commission, 2026, https://leedsclimate.org.uk/lcc-news/case-study/ten-years-on-how-devastating-floods-led-to-a-more-resilient-city/ - "Leeds Flood Alleviation Scheme", Arup, https://www.arup.com/projects/leeds-flood-alleviation-scheme/ - "The Leeds Flood Alleviation Scheme (FAS)", Leeds City Council Flood Resilience, https://leedscitycouncilfloodresilience.commonplace.is/en-GB/proposals/leeds-flood-alleviation-scheme/start