A leading engineering consultant is urging immediate government action to build “check dams” in the gullies that feed into Charles Rowe Bridge, St George, after Sunday’s deadly flood claimed one man’s life and swept away cars.
Andrew P. Hutchinson, director of A H Consulting Inc., said on Thursday that, contrary to popular belief, the answer does not lie in adding more soakaways, as these cannot handle the massive runoff volumes that accompany extreme storms.
Hutchinson said: “The most effective mitigation measures require the construction of small check dams at intervals in the gullies to retain the runoff and provide storage and attenuation of the peak flow. This method utilises the existing storage capacity of the gully for attenuation, with the added benefit of recharging the aquifers.
“Prior to the construction of check dams, a digital hydrological model should be prepared to confirm the efficiency of the proposed check dams – this technology exists and should be used.”
He added: “It is imperative that we prioritise this matter to minimise future flooding of communities by extreme rainfall events. The economic impact of these flood events is not insignificant, and our development plans must incorporate the necessary mitigation measures.”
A topographical map of the island shows five gullies converging on Charles Rowe Bridge, just north of Chefette Restaurant.
These gullies have a collective watershed of 2 765 acres to the north of Charles Rowe Bridge, including the urban communities of Airy Hill, Rowans Development, Flat Rock, Rowans Park, Thorpes, Walkers, Gun Hill, The Valley, Newbury, The Glebe, Bridge Cot, Bournes Village, Locus Hall and other areas of active and inactive farmland.
Hutchinson said: “Utilising published rainfall data on Barbados — eight to nine inches — the event of November 16 can generally be categorised as having a recurrence interval of one in 15 years, or a seven per cent chance of occurrence in any year. It appears that the cloud mass delivered rainfall across the whole watershed at the same time, producing the maximum effect. This is not often the case as storm patterns may only cover a part of the watershed.”
The engineer contended that while the gully systems provide natural drainage for Barbados’ limestone landscape, continued development without appropriate drainage and mitigation measures will result in incidents like those on Sunday at multiple locations.
He recalled that Barbados has experienced major flooding episodes throughout the years, noting that all of these events were associated with heavy rainfall from tropical systems coming off the Atlantic, predominantly during October and November.
Terry Kellman, 58, was swept away after losing his footing along Lower Estate Road as floodwaters turned the nearby Charles Rowe Bridge into a raging torrent, witnesses said. His body was found on Monday morning, a short distance away.
Insurers are bracing for tens of thousands of dollars in motor claims after Sunday’s record-breaking floods, which caused widespread destruction of vehicles, with scores of cars washed away or written off across the island.
Notable floods
Jordan Flood – 1901
Constitution River – 1949 and October 1970
Weston ‘Carew’ Flood – 1995
Woodbourne – ‘Tomas’, 2010
Holetown and Speightstown – several floods including the Speightstown flood of 1984
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