Key Facts and Questions
At a cost of £150 million does the Oxford Flood Alleviation Scheme add up? Could the most effective elements be retained with an alternative design for the controversial channel?
The value added by the controversial channel
The channel generates just under 5% of the benefits for just over a quarter of the cost of the scheme. Is the channel worth it?
The economics suggest taking a hard look at the components of the scheme.
Amount of flood water carried by the proposed Oxford Flood Alleviation Scheme channel and "lowered floodplain".
Is this enough to deal with the volume of water in a flood event when more conventional schemes carry
of the benefits are delivered by just 8 of the 13 elements of the scheme.
Could the more cost effective elements of the OFAS scheme be retained with an alternative to the controversial channel?
This is all that remains of UK's iconic meadows with 97% lost since World War 2.
Hinksey Meadows is an ecological treasure chest with 7 hectares of rare MG4a flood plain meadow including fritillaries. 2 hectares will be lost. The rest is threatened by changes in hydrology.
What is the true ecological impact of the flood scheme?
The increased water volume in our rivers due to climate change.
The Oxford Flood Alleviation Scheme is designed to deal with a 1 in 100 year flood event. But as weather patterns become more unpredictable, what are the odds of major flood events happening more frequently due to climate change?
of benefit delivered by just 3 components of scheme for £20 million.
Just 3 elements, resolving the pinch points at the Old Abingdon Bridge, the Botley Rd/Tumbling Bay and the Willow Walk bridge works, produce a large benefit for 40%. Should the Environment Agency concentrate on delivery of the most cost-effective parts of the scheme?
And how should we account for the environmental impact of the carbon cost and loss of amenity during the construction?
KEY QUESTIONS ABOUT THE OXFORD FLOOD ALLEVIATION SCHEME
IF OXFORD IS FACING A DRAMATIC INCREASE IN FLOOD RISK DUE TO CLIMATE CHANGE - WILL THE SCHEME WORK?
The scheme is designed to cope with a 1 in 100 year flood event but this is already outdated. With the MET forecasting increased rainfall of 30-40% and river flows set to rise by 30%, the efficacy of the channel design, which will carry 15% of flood flow, is in serious doubt. More conventional schemes carry 40%. Even the Environment Agency's business case admits that the efficacy of the scheme will decrease over time. In an extreme flood event, the reduction of flood water will be about 20 centimetres. Not much more than the length of a pen.
Given the massive cost and upheaval there are serious question marks around whether the scheme is future proof.
DOES THE SCHEME REPRESENT VALUE FOR MONEY?
The scheme will cost around £150 million. The estimated financial benefits due to reduced flood damages and impacts on the city over 100 years are in excess of £1.5 billion. However, this is an unusual way of calculating benefit, given the uncertainty of climate change.
Also 85% of the projected benefits would come from continuing the existing flood alleviation measures. The EA has also only costed the first 10-15 years of maintenance.If the full costs were included, this would increase the scheme's cost. Also failure to deliver proper maintenance will greatly diminish the effectiveness of the scheme.
86% of the benefits derive from just 8 components of the scheme, with three elements representing 40% of these benefits. There has been no proper accounting for loss of amenity and Ecosystem services costs. Nor has carbon cost been reckoned.
The question to consider is, if all of these issues were taken into account, what would be the true cost and benefit of the scheme?
WHAT ABOUT THE CARBON COST AND THE ENVIRONMENTAL IMPACT?
The site comprises 133 acres of green belt. 700 thousand tonnes of alluvial soil and gravel will be removed. Thousands of trees and acres of hedgerows. 2 hectares of the precious ecology of Hinksey Meadows will be lost and the rest threatened by changes in hydrology. It is now known that soil disturbance contributes to release of CO2. Also removing so much soil will disrupt the mycorrhizal network of the soil - the "wood-wide web" of fungi that creates a symbiotic relationship with plants that will take many years to recover. There is growing research that floodplain meadows and grassland are second only to peatland as carbon stores. What's more they we are beginning to understand that "carbons in trees, plants and soils is 'irrecoverable' meaning that natural regeneration could not replace the loss by 2050, the date by which net global emissions must end to avoid the worst impacts of global warming." Scientists are now advising that these places should be protected as a priority. We must keep irrecoverable carbon in the ground.
Has the EA fully calculated the carbon cost of drastically altering the historic, ancient flood plain of West Oxford?
WHAT ABOUT POLLUTION AND TRAFFIC DURING CONSTRUCTION?
With 700 tonnes of soil and gravel needed to be excavated to create the 5k channel, it is estimated 30-40,000 lorry journeys will be needed, to access the A34 through Hinskey Village. Given that air pollution kills ten times more people than the flu every year and more than 4 times the official death toll from Covid last year, such a dramatic increase in particulates in the air could have a devastating effect on the health of Oxford's population. Added to this, the loss of trees, and the local amenity of the landscape, the overall hidden cost of the project could be far higher than the current projections suggest. There is also widespread development planned for West Oxford, with Oxwed putting in a planning application in early 2022 for dramatic development of the so called "west end quarter." What is the real cost to health of so much construction?