EXPERTS in Oxford have warned that natural defences are not a 'silver bullet' for flood prevention.

Researchers released a study today suggesting natural methods such as planting trees and creating wetlands may not protect against severe flooding. 

Academics suggested measures to manage the risk from rivers could play a valuable role in curbing floods on a small scale, but there is little evidence to suggest they work with the worst case flooding. 

Lead author Dr Simon Dadson, of Oxford University, said: "When it comes to natural flood management, there are some interventions for which there is very strong evidence, but these tend to be in small-scale river catchments.

"One of the main problems decision-makers face is that differences between catchments make it difficult to transfer evidence from one location to the other - and we don't yet know whether the effects in small catchments can be extrapolated to larger ones.

"Natural flood management can help if implemented well in carefully chosen locations, and it can bring important benefits to landscapes and wildlife, but it's not a silver bullet for the problem of flooding."

Oxford Martin School published the paper in a science and engineering journal called Procdeedings of the Royal Society A. 

It was written by academics across the country including a team at Oxford University. 

The Environment Agency continues to gather £120m to fund the Oxford flood alleviation scheme, which would involve building a manmade channel from Botley Road to Kennington.