Thousands of homes in South and central Bristol at risk as climate change progresses

March 01 2019

A TIDAL barrier similar to the Thames Barrier in London is among plans to prevent a devastating future flood in Bristol.

Flood risk map 1Flood risk map 2

Pictured: the flood risk maps shown to councillors

By Adam Postans

Local Democracy Reporter*

A TIDAL barrier similar to the Thames Barrier in London is among plans to prevent a devastating future flood in Bristol.

About 1,000 homes and businesses throughout the city are currently at risk from a tidal surge from the Severn Estuary, but with sea levels rising because of climate change, experts say that figure will soar to 2,300 homes and 1,350 existing firms within a century.
City council officers revealed a tidal barrier was under consideration during an annual update on Bristol’s local flood risk management strategy to the growth and regeneration scrutiny commission.
Like the one on the Thames, the structure would be kept open most of the time but could be closed during high tides.
It is part of a long-term plan alongside riverfront defences, such as flood-proof fences.
Officers said they had rejected other options including dredging, a flood relief tunnel, enhancing operations at the harbour and holding back river flows further upstream.
They also threw out the idea of a tidal barrage, or dam, because it would not allow the rivers flowing into Bristol to reach the sea, which could actually make the situation worse.
City council flood risk manager Patrick Goodey told members on Thursday, February 21: “Our strategy is aiming to reduce the risk to the city for the next 100 years.
“Measures that are under further consideration include a tidal barrier. These are like the Thames barrier.
“It would be completely open for the majority of the time and we could close this in advance of a high tide.
“It’s much less environmentally damaging than a barrage and allows the normal flows of the river.
“The reason we’re calling this a strategy is that we would not have to do that tomorrow.
“We could do a combination of riverfront fences plus a barrier at some stage in the future, depending on how climate change is progressing.
“Those are the two options we’re moving forward with and exploring at the moment.”
Mr Goodey said that since the city’s flood management strategy was launched in 2014, the council had reduced the flood risk to at least 220 homes.
He said: “Central Bristol has two major sources of flood risk.
“We have flood risk from the tidal surge, when we have high spring tides coinciding with bad weather out in the estuary and the Atlantic.
“We then have the river flows that come in from the Avon catchment.
“There is a significant amount of water that all bears down on the city. They converge in the centre of the city.
“The risk of a significant flood  is relatively low.
“If we did have this event, we would have about 1,000 homes and businesses flooded throughout the city.
“A significant high tide of this event would be over nine metres. The level of the harbour is six metres.
“In this event, the river would flood over into the harbour, fill up the harbour and then flood out from there.
“We had a significant event in 1968 and, in response to that, the city has been very good at installing significant infrastructure.
“We’ve got a number of tunnels throughout the city that now divert flood water, so if we had a 1968 event, the flooding would not be as bad as it was back then.
“We want to manage these risks proactively, we don’t want to wait for events to happen.”
Recent flood prevention works carried out by the council include improving river control structures in Victory Park, Brislington, and Trevisa Grove, Bentry.
The team also reviews planning applications, which has resulted in about 250 developments incorporating sustainable drainage systems in their designs/
Areas west of Temple Meads are mostly at risk from a tidal flood whereas land to the east is threatened more by rivers flowing downstream.

 * The Local Democracy Reporter scheme is funded by the BBC out of the TV licence. It pays for 150 reporters around the country to cover some of the issues that newspapers often do not have the staff for any  more – mainly council issues but also involving other public bodies including the police and schools. South Bristol Voice is a member of the scheme, which means we have the right to use the stories produced by the three Local Democracy Reporters in Bristol. We aren’t able to influence which stories are chosen or how they are written. The  Local Democracy Reporters work at the offices of Bristol Live (publisher of the Bristol Post) and are managed by Bristol Live.