OXFORD NEEDS A BETTER FLOOD SCHEME
Riki Therivel and Tim O’Hara
The Environment Agency will soon be putting in a planning application for a £154 million Oxford Flood Alleviation Scheme (OFAS). This would involve digging a 5km ‘sculpted channel’ from north of Botley Road to north of Kennington, plus other measures such as bunds at South Hinksey. When the planning application is in, we will all have the opportunity to comment on it. We believe that Oxford badly needs flood protection, but the OFAS is an environmentally destructive, over-costly way of doing this. The Environment Agency has refused to consider cheaper and less harmful alternatives.
Environmental harm: The OFAS will lead to the destruction of thousands of mature trees, and two hectares of beautiful and rare MG4 meadow (Hinksey Meadow), as well as threatening the remaining meadow. Nobody has yet successfully transplanted MG4 meadow. Digging up 400,000 cubic metres of soil from Oxford’s millennia-old floodplain and felling the trees will release huge quantities of carbon.
During the project’s 3-4 year construction period, access to the site will be severely restricted. Removing the soil will mean tens of thousands of additional HGVs on the A34. The HGVs will accelerate slowly, further increasing congestion on the ring road. There will be disturbance and other impacts at South Hinksey from lorries going in and out there.
Lack of long-term management: After construction, the presence of the channel plus new fencing will affect grazing and limit recreational use of the area. The OFAS plan includes only 10 years of maintenance (it is unclear what ‘maintenance’ would look like). There is no budget for maintenance after the first 10 years: land owners are expected to do this. Without maintenance, vegetation build-up could inhibit the flow of water, reducing flow capacity and limiting the scheme’s ability to protect properties from flooding.
Too costly: Digging the channel is the most costly part of the scheme, but the least effective. 85% of the OFAS benefits in terms of reducing flood damages would come from continuing existing flood alleviation, notably the conduits under Willow Walk. Most or all of the rest of the benefits come from bunds around South Hinksey, defences at Osney Island etc. – NOT from the destructive channel. The marginal benefit-cost ratio of the channel is at best 1.66 :1. This does not include the costs of reduced recreation, tranquillity, biodiversity, carbon fixing and long-term maintenance, which further increase the scheme’s costs.
Reasonable alternatives not considered: Legally the Environment Agency must consider ‘reasonable alternatives’, but it has not considered any alternative to a channel / floodplain lowering since 2009. Reasonable alternatives that could provide as much or more protection from flooding at lower financial, environmental and social costs include:
- Underground pipes broadly along the OFAS route, with pumps that switch in automatically before flood events become damaging;
- Putting in components of the OFAS (bridges at Willow Walk, bunds at South Hinksey, rail bridging at Old Abingdon Road etc.) but no channel to start with, monitoring effectiveness, and adding a channel or pipes if necessary.
We encourage people to ask about these points when the Environment Agency puts in a planning application for the OFAS. Further information is available at https://www.gov.uk/government/publications/oxford-flood-scheme/oxford-flood-scheme, www.hinkseyandosney.org and www.oxfordfloodandenvironmentgroup.com.
Published in the Sprout, March 2022