Leeds Flood Alleviation Scheme Phase One
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Leeds Flood Alleviation Scheme Phase One

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Phase One of the Leeds Flood Alleviation Scheme uses innovative technology to reduce the risk of flooding in the city centre.

Funding for the scheme was secured through contributions from Leeds City Council, Environment Agency, Defra, Regional Growth Fund, Leeds City Region Enterprise Partnership, Yorkshire Water and CEG.

The scheme was officially opened on 4 October 2017 by Leader of Leeds City Council, Councillor Judith Blake and Chair of the Environment Agency, Emma Howard Boyd.​

Phase One is made up of 3 main elements:

  • Moveable weirs
  • Merging of the river and canal
  • Flood walls, glazed panels and embankments stretching more than 4.5km

It is the first time moveable weirs have been used for flood risk reduction purposes in the UK. The weirs; at Crown Point in the city centre and further downstream at Knostrop can be lowered to create more room for flood water, with the potential of reducing flood levels by up to 1 metre.

The removal of a 600m stretch of land known locally as Knostrop Cut island has allowed the river and canal to merge. This has created additional capacity for flood water, helping to lower levels in flood conditions.

At Knostrop, a new locally manufactured bridge has been installed across the weir to connect the Trans Pennine Trail with the north bank of the river.

Work continues to construct flood defences along the length of Hol Beck which flows into the River Aire adjacent to Granary Wharf. Work is expected to be complete in January 2018. Traffic management measures previously in place to allow construction of the defences are no longer in operation as part of this work.

Elsewhere, low level embankments have increased the level of protection in Woodlesford.


Stay up to date

The project team produces a regular newsletter which is available in the Documents section.

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Click to expandScheme Features

Phase 1 of the flood alleviation scheme was initially designed to protect Leeds city centre (between Leeds station and Knostrop weir) from a flood event with the likelihood of occurring once every 75 years. However, with the additional funding awarded by the Leeds City Region Local Enterprise Partnership in 2016, the standard of protection is being increased to now provide protection against a flood that is likely to occur once every 100 years (or has a 1% chance of occurring in any given year). Work to increase the standard of protection will not affect the completion date for the scheme which is on track for summer 2017.

Key elements of the scheme include:

- Remove the existing weirs at Crown Point in the city centre and at Knostrop and install moveable weirs that can be lowered when the river is high, causing the water level to drop. An animation showing how the moveable weirs operate can be viewed on YouTube. In addition, a simulation of how the moveable weir is being installed at Crown Point can also be viewed.

-Construct linear defences such as low level embankments, terracing and riverside walls; at low points along the riverbank;

-Remove Knostrop Cut Island to merge the canal and River Aire which will help facilitate the flow of water when the moveable weirs are lowered as well as creating somee additional flood water storage;

-Provide flood defences along a length of HolBeck located on Water Lane;

-Provide defences to Woodlesford in the form of low level embankments to protect against a flood event that is likely to occur every 200 years (or has 0.5% chance of occurring in any one year);

-Details of the planning permission application can be viewed.

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Click to expandLeeds FAS Project team

The Leeds Flood Alleviation Scheme is being delivered by Leeds City Council in partnership with the Environment Agency and supported by Arup. BMMjv (a joint venture between BAM Nuttall and Mott MacDonald) are working closely with the partnership to deliver the scheme.​

Click to expandFunding the scheme

The Leeds Flood Alleviation scheme is being funded by Leeds City Council, the Department for Environment, Food and Rural Affairs (Defra), the Environment Agency and the Department for Business, Innovation and Skills (BiS).​

Click to expandCity centre public rights of way closures

​​For more information please click on the link below.

City centre closures document

Click to expandTrans Pennine Trail closure and route diversion information

A section of the Trans Pennine Trail along Knostrop Cut has been closed to allow major construction of flood defences along the River Aire. The work includes the removal of the Knostrop Cut island and the relocation of the Trans Pennine Trail along the northern bank of the river. A temporary diversion has been signposted along the south bank of the river to provide an alternative route until the new permanent diversion is opened on completion of the scheme in summer 2017. You can download a map showing the route of the pedestrian and cycle diversion in the Documents section on this page.

To enable efficient construction of the Flood Alleviation Scheme and ensure safety of the public, there will be some additional closures to the Public Rights of Way (PROW) along the waterfront. Details of these closures and the associated diversion routes can also be found in the Documents section.​

Click to expandKey Project Milestone Summary

Description Start Date End Date
Project End Date - July 2017
Knostrop Weir January 2015 May 2017
Crown Point Weir January 2016 July 2017
Linear Defences January 2015 July 2017
Knostrop Cut March 2015 April 2016
New Trans-Pennine Trail May 2017 June 2017
River closures 15 February 2017 13 April 2017
15 May 2017 12 June 2017
21 June 2017 18 July 2017
​(*NB - Dates correct at time of publishing - January 2017)​​

Further information on work start dates can be found in the link below.​​

Construction commencement dates

Click to expandWhat do we mean by flood risk?

This is the chance of a flood happening. Generally, the higher the figure used in the description of the flood risk, the less chance of it happening. For example:

An area with the chance of flooding of a 1 in 75 (1.3 percent) in any one year has less chance of flooding than another with say an annual probability of flooding of 1 in 25 (4 percent).

It is important to understand that a 1 in 75 chance of flooding in any one year does not mean that level of flood will happen once every 75 years. Nor does it mean that if the flood hasn’t happened for the last 74 years, it will happen this year. ‘Any one year’ means exactly what it says, in that the risk is expressed on a yearly basis. A flood may also occur more than once in a year.

Click to expandWhy has this level of protection been chosen?

The scheme was originally designed to reduce flood risk up to a 1 in 75 year event. This was the highest level of protection which could be provided at the time with the funds that were available. Since receiving the additional funding from the Leeds City Region Local Enterprise Partnership, we have been able to increase the level of protection to 1 in 100 years while continuing to maintain the public’s access and enjoyment of the riverside.​

Click to expandHow does the introduction of moveable weirs improve flood protection?

Weirs keep river levels high to allow for navigation. By replacing fixed weirs with moveable weirs we will be able to lower river levels by up to one metre during flooding conditions, thereby creating additional capacity for flood water in the river channel.​​

Click to expandIs flood protection upstream of Leeds station planned?

Yes. Following the December 2015 floods, government committed an additional £35 million to reduce the risk of flooding to Leeds. Planning for Phase 2 of the Leeds Flood Alleviation Scheme is now progressing. The current Phase 1 of the scheme covers the section between Leeds train station and Thwaite Mills. Visit the Phase two page for more information.​​

Click to expandWill flooding risk be increased further downstream?

Our specialists carried out thorough assessments during the design stage of the scheme to ensure that one community is not protected at the expense of another.

The scheme will have a neglible effect on flood risk downstream of Thwaite Mills. Mitigation works have already been implemented in Woodlesford to give the area a 1 in 200 year SoP, whilst the impact on the remaining downstream areas is minimal due to the large areas of designated floodplain.​

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