Pickering's "Slowing the Flow" scheme reduced river peak flow by 15-20 per cent during last December's floods when a total of 50mm of rainfall fell over a 36-hour period, preventing the flooding of a number homes and the town's museum, the study by the scheme's partnership found.
The partnership, set up after the town saw four serious floods in 10 years, combines conventional upstream flood storage with a wide range of measures designed to hold water on the land and slow the speed at which it enters the river system.
In addition to the construction of a flood storage reservoir, 40,000 trees were planted, local heather moorland was restored and more than 300 "leaky" dams were built in forest and moorland drains and streams in the upper catchment. The new analysis estimates that around half of the flow reduction was due to the upstream land management measures and half due to the flood storage area.
Environment Agency executive director of flood risk management John Curtin said: "Natural flood risk management measures when used alongside more traditional flood defences can make an effective contribution to reducing flood risk, as demonstrated in Pickering. They can also deliver more benefits, such as improving water quality, preventing erosion and storing carbon."
Slowing the Flow partnership chairman Jeremy Walker added: "This is good news for the town, although the measures installed have their limits and would not be enough to prevent flooding in the event of rainfall on the scale experienced, for example, in 2007." On that occasion damage estimated at £7m was caused to the town.