EXPERTS in Southampton say that the "strategic" planting of trees on floodplains could reduce levels of flooding.

A team from the university has worked with fellow experts from the University of Birmingham on a study showing the trees could reduce the height of flooding in towns downstream from the floodplains by up to 20 per cent.

It comes two years after Hampshire was hit by some of the worst flooding in a generation with the military called in to protect homes and businesses in Winchester, while Romsey was also afflicted by floods.

Published in the Earth Surfaces Processes and Landforms journal, they looked at an area of 100 square kilometres upstream from Brockenhurst in the New Forest.

They looked at how tree planting, river restoration and "logjams" could affect the "peak height" of a flood in a town downstream.

They found that planting trees on floodplains and increasing logjams across 10-15 per cent of the river's length could reduce the highest point of flooding in the town by six per cent, after trees had grown for 25 years.

More extensive floodplain forests and improvements to rivers resulted in the peak height of floods being reduced by up to 20 per cent, with that trend continuing the older and more developer forests were.

The study was funded by the Environment Agency, which is looking at different ways to tackle flooding and reduce potential damage to areas.

Dr Simon Dixon, from the University of Birmingham’s Institute of Forest Research (BIFoR), lead author of the study, said: “As our research shows, targeted tree planting and restoration can contribute to reducing flood risk. "We believe that tree planting can make a big contribution to reducing flood risk, and should be part of a wider flood risk management approach, including conventional flood defences. "Tree planting would represent an extra element that helps to slow down the arrival of rain water to vulnerable locations.”

Professor David Sear from the University of Southampton, who supervised the project, said: “With increasing interest in alternatives to conventional hard flood defences, there is an urgent need for evidence that these alternatives can work.

"This research reminds us that natural processes, when targeted carefully, can reduce downstream flood risk alongside other societal benefits including biodiversity and recreation.”

They also looked at man-made dams which have been thought to have a positive impact on flooding.

They found that while the dams can slow the flow of water, it does not necessarily reduce flooding.

Dr Dixon added: “Logjams contribute to slowing the flow by backing up water and pushing it onto the floodplain. In locations where the floodplains are meadows or crops the water may still be able to flow over the surface quickly. "To make the best contribution to flood mitigation it is important they are used in locations with complex bankside vegetation to slow water flowing over the floodplain.”