Hampshire County Council, as Lead Local Flood Authority, has published the independent consultant's report on the flooding in the Romsey area this winter.
The formal investigation was launched in January to look into the causes of flooding, what could be done to address these in future, and the responsibilities of different organisations to mitigate the risk of flooding. It focused on specific areas of Romsey affected by flooding: Cupernham Lane, Winchester Road, Middlebridge Street, Riverside Gardens, Mainstone and the Causeway.
The report from technical specialists CH2MHILL, concludes that the Romsey area was affected by fluvial, surface water, foul water and groundwater flooding, with a total of 96 properties affected.
At Cupernham Lane, surface water runoff was largely due to the terrain and high groundwater levels; at Winchester Road, groundwater levels led to cellar flooding and inundated sewers led to surface water flooding. At Mainstone and Causeway, a combination of surface water from the road, groundwater levels and excess water in local watercourses all contributed to the flooding of properties. Properties in Riverside Gardens were affected by surface water from the sewer networks, and some properties were directly affected by the River Test overflowing. Middlebridge Street was affected by surface water flooding from the sewers and groundwater.
The report concluded that the new development at Abbotswood did not result in an increased flood risk to Cupernham Lane, and may have slightly alleviated the flooding there. However, the report did suggest that more could have been done in the earlier stages of the development to assess the risk of flooding offsite and has recommended that a revised drainage strategy is implemented. Other potential options in the area are now being explored, with Mainstone and Causeway identified as a priority area.
Councillor Roy Perry, Leader of Hampshire County Council, commented: "We commissioned this independent investigation to find out about the causes of the flooding problems across Romsey and what corrective or improvement actions might be required to help mitigate the risk in the future. Now we have the results of the investigation, we will continue to work closely with our partners including Test Valley Borough Council, the Environment Agency and Southern Water to determine what actions can be prioritised immediately and what additional steps need to be taken to help address future flood risk.
"Bids for Government grants to support further investment in flood defences for Romsey and across Hampshire were submitted earlier this year by the County Council and the Environment Agency, and the results of these funding bids should be known in the autumn. In the meantime, we will also be focusing additional resources on maintenance of our highway drainage systems and flood defences and reminding landowners of the importance of keeping ditches clear and well maintained for next winter."
Earlier this week Councillor Perry met with water companies and energy suppliers to discuss ways to improve Hampshire's resilience against future extreme weather conditions, through joint working. The partner organisations have agreed to continue to work closely together, sharing technical expertise and knowledge, for instance, on the relationship between groundwater levels in boreholes and flooding incidents, the location and resilience of critical infrastructure such as water or electricity sub stations, or access to aerial photographs and flood mapping to help inform plans for future flood defences.
The County Council is currently awaiting news of the bids for financial support it has submitted to Government to pay for the costs of repairing the damage caused by the wettest winter since records began.
Hampshire Fire and Rescue Service is leading on an exercise to bring together all the lessons learned during this winter's flooding across the county and a further report is expected later this year.