Year
2019-2024Duration
6 yearsCost
£200 million (for phases 1 and 2)Location
United KingdomProject achievements
Solved the problem
Offers protection from major flooding for the communities along the River Aire
Environment benefitted
Employs nature-based solutions to slow the flow of water during heavy rainfall
Used engineering skill
The project features innovative mechanically operated floodgates
Protect Leeds from a 1-in-200-year flood
The Leeds Flood Alleviation Scheme is one of the largest and most innovative natural flood management projects seen anywhere in the UK.
It aims to reduce flooding and provide a 1-in-200-year level of protection for 1,500 homes and 370 businesses on the River Aire.
Phase 2 began in 2019 and delivered measures in two stages:
- Creating a major storage facility upstream boasting two innovative mechanically-operated floodgates.
- Building linear defences along 14km of the river, from Leeds Station to Apperley Bridge, including flood walls, embankments and trees.
In 2025, the project took home the Centenary Award at the ICE Yorkshire and Humber annual civil engineering awards.
Did you know …
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If LFAS operates at full potential once, it will have saved more carbon than was required to build it, a study by the University of Edinburgh has found.
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The mechanically operated storage area near Calverley boasts two innovative floodgates which, when needed, will hold up to 1.8 million m3 of flood water. This would fill more than 720 Olympic-sized swimming pools.
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Across the Aire catchment, the project team planted over 750,000 trees and aerated (increased airflow and oxygen) more than 1,200 hectares of soil, the equivalent of 1,700 football pitches.
How was the scheme built?
Flood storage
A key feature was the creation of a mechanically operated flood storage area, away from highly populated zones.
The 200m long, 6.2m high earth embankment was innovatively formed using natural materials, such as clay, from an onsite borrow pit (an excavated area) in a nearby field.
This saved over 5,000 heavy goods vehicle (HGV) journeys and their associated greenhouse gas emissions.
The storage area was designed to hold up to 1.8 million m3 of floodwater in the event of extreme river levels.
It features two innovative moveable floodgates, controlled on a minute-by-minute scale.
The gates can be raised and lowered to slowly release the water downstream in a controlled way once the threat of flooding has passed.
Linear defences
The scheme included the construction of defences over a 14km stretch of the river, upstream of the city centre along the A65 (Kirkstall Road).
This involved traditional engineering methods such as raised flood walls, embankments, flow control structures and conveyance improvements (removing obstructions from the river to allow more water to pass in flood conditions).
Two pumping stations were built to control surface water flood risk, with another station managing seepage beneath a long earth embankment (a much lower whole-life cost solution than constructing a seepage cut-off).
To protect three historic mill goits (man-made channels), active flow control structures were provided at the up and downstream.
These isolate the goits as the river level rises, removing the need to construct linear defences in this area.
Natural flood management
Over 500,000 trees were planted as part of the scheme.
Soil and land management measures were introduced across 1,700 football fields’ worth of land (1240ha) to capture and slow the flow of water down the river during heavy rainfall. These reduce peak flows by up to 5%.
These measures protect communities downstream, while also creating habitats, capturing and storing carbon, and increasing the resilience of farmland. It’s also improved water quality and reinvigorated outdoor spaces.
A 2.4-hectare wetland habitat on Kirkstall Meadows has been created using river scrapes, while more than 90,000 further trees and shrubs have been planted throughout the Leeds area.
The team also added floating riverbanks, vegetated walls and landscaping to along the defences.
Difference the project can make
The Leeds Flood Alleviation Scheme project has transformed the River Aire’s communities.
It has delivered economic, social and environmental benefits while supporting the future growth of the region.
It’s expected the regeneration will deliver £774M over 10 years and create between 1,600 to 3,500 jobs.
The protection offered by the scheme increases the resilience of key infrastructure in Leeds, such as power supplies, communications networks, and travel routes.
This includes the railway at Kirkstall, which connects a significant portion of Yorkshire and had previously been at risk, causing regular disruption to rail travel.
