Councillors have asked for a briefing on a huge investment project which aims to protect hundreds of Southampton homes and businesses from flooding.

The River Itchen Flood Alleviation Scheme (RIFAS) is a partnership scheme between the city council and the Environment Agency.

Proposals have been progressing in recent years to reduce the risk of tidal flooding over a 2.2-mile stretch along the west bank of the river.

READ MORE: River Itchen could have movable barrier to stop high tides

Focus has been placed on the areas of Northam, St Mary’s and Chapel.

The plans cover from Mount Pleasant Industrial Estate in the north down to Southampton Water Activities Centre to the south of Itchen Bridge.

As reported, in 2021, the project was estimated to cost £41million, however, a recent council meeting heard it could now be in the region of £70million with an outstanding funding gap.

The RIFAS was brought up at an overview and scrutiny management committee (OSMC) meeting during discussions on progress made in relation to recommendations from the Protecting, Preserving and Promoting the River Itchen in Southampton inquiry.

Committee member Cllr Steve Leggett, who was the cabinet member responsible for flooding from 2018 to 2021, said: “RIFAS is from Northam Bridge round to Itchen Bridge. That’s the bit it covers where the football stadium is.

“That is based on the fact that the projections from Defra, which we got in 2016, were that there would be significant flood risk over the next 100 years and that was based on a 2C rise in global temperatures.

“It would affect the city centre, it would affect the football stadium, it would affect 10 wards in the city.

“Project RIFAS is way ahead of its game in terms of reducing flood risk and that area around the stadium is one of the highest flood risks, so therefore it has got low commercial value or low value in total.

“That doesn’t mitigate from what is causing the temperature rise, it just protects it.”

Chair Cllr Richard Blackman said the committee was clear that the scheme was “critical to the growth and prosperity of the city”.

However, he said there had not been an answer about the progress of the project and any funding gap at the committee meeting.

Cabinet member for green city and net zero Cllr John Savage said: “I have been to meetings where it has been discussed.

“The amount of money that has been invested in it so far and the shortfall of that money going forward that will be required to protect that part of the city.”

Cllr Leggett said the last cost figure for the project he received was £70million.

“I think it would be quite a good item of future OSMC,” Cllr Leggett said.

“It is such a critical investment in the infrastructure of the city, for the growth of the city and it would be good to get more detail.”

The committee agreed that a specific item on RIFAS would be put on the agenda at a future meeting, with the date to be determined.

The Environment Agency and council agreed a partnership to relaunch RIFAS in early 2019. The timeline five years ago said detailed design work could take until 2027 before a full business case is presented.

The council’s webpage on the project said there were currently more than 100 homes and more than 200 businesses at risk of tidal flooding.

New flood risk management infrastructure would reduce the risk for more than 1,100 and 900 businesses by 2,115, the council says.