A £7.7 MILLION new flood defence scheme could fail to protect scores of York properties from being flooded by the River Ouse, two retired civil engineers have claimed.

Christopher Rainger and Andrew Burnard claim that the Environment Agency’s computer modelling for the Clementhorpe project is inaccurate and the flood barriers will be too low and could be overtopped if the River Ouse rises any higher than the record levels reached in November 2000.

The claims have been vigorously denied by the agency, which says it is confident the defences - which it is just starting to build - would protect 135 properties in the community.

Mr Burnard, of Clementhorpe, a Fellow of the Institution of Civil Engineers, and Mr Rainger, a former Fellow who spent much of his career working on water-related civil engineering for British Waterways, including flood risk assessment and prevention schemes, claim the predicted maximum flood levels for the Clementhorpe area have been miscalculated and are too low.

They say the model includes an allowance for climate change, which predicts an increase in the flow at Skelton from the 604 cubic metres of water per second reached in 2000 to 621 by 2039.

They say it also predicts a higher flood level at the Viking Gauge, between Ouse and Lendal bridges, but ‘perversely’, predicts the maximum flood level at Clementhorpe will be lower than levels recorded at this point in 2000 flood. “This cannot be right,” they say.

They also claim the ‘Freeboard’ between the predicted maximum flood levels and the tops, or crests, of some of the new flood walls will be too small.

They say they contacted The Press after reading how the EA had delayed its flood defence scheme for Tadcaster by two years because its computer modelling was inadequate.

But Ben Hughes, of the Environment Agency, said there were ‘no parallels’ between York and Tadcaster, and said the modelling, design and planning process it was using in York was in line with current best practice and it was confident it had identified the best solution to reduce flood risk in the area.

He said the agency was confident the defences would be sufficient to cope with a repeat of November 2000, when the Ouse reached a record height of 5.4 metres above normal summer levels, causing severe flooding in Clementhorpe.

He said the flood modelling had been carried out by consultants who were 'professional river modellers,’ and it had been internally reviewed.

Mr Hughes said that over coming decades, the agency also intended to take action in the Ouse catchment in the Dales to ‘slow the flow’ downstream in York, when there was heavy and persistent rainfall in the Dales, such as improvements to flood storage areas.

He claimed the agency had spent a great deal of time engaging with the two retired engineers and had reached a point where it had had to agree to differ.

He added that to raise the levels of the defences in Clementhorpe at this stage - as suggested by the engineers - would impact on the scheme’s cost and financial viability.

Mr Hughes said it was important to distinguish between the ‘peak flood level’ generated by the agency's modelling and the ‘crest level’ which was used for its defences.

"In referring to the maximum flood level at Clementhorpe, Mr Burnard and Mr Rainger are only referring to the peak flood level," he said.

"We have acknowledged that the peak flood level, on its own, appears slightly low and is incrementally (i.e. less than 0.01 per cent) below the record flood level recorded at the gauging station relied upon by Mr Burnard and Mr Rainger.

"However, the final height of the flood defences (the crest level) consists of the peak level generated by our flood modelling and a freeboard allowance.

"Once the freeboard allowance is added, the height of our flood defences will be higher than any historic flood recorded at this gauging station."

York Central MP Rachael Maskell said that although she was not an engineer, she had “listened carefully” to both Mr Rainger and Mr Burnard’s concerns and the response to them from the Environment Agency.

The retired civil engineers took their misgivings about the Clementhorpe flood defence scheme to the MP, in January, telling her: “We will be grateful if you will take up this issue at a high level with the Environment Agency, and/or whatever authorities you consider appropriate, to ensure that adequate flood defences are provided to protect properties in the Clementhorpe area.”

She told The Press that the transition of Viking Recorder data to Clementhorpe was “not linear, due to river infrastructure and flow streams, river width and depth”, and because of this, there were “some challenges” in their counter proposal.

“However, it is absolutely right that constituents scrutinise and challenge the plans of statutory authorities and I have been pleased to have been able to put their case to the Environment Agency and cause them to examine the issues raised,” she said. “Transparency is vital, not least when public money is being spent.

“With further mitigation planned upstream with natural flood management, something I have been campaigning on since 2015, we should see better flow management and cut flooding risk in York.”