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How roads become rivers

  • by JW

How flooding on our roads is not going to get much better any time soon…


There are fears of roads turning into rivers – with flood warnings in place as heavy rain lashes Devon.

Why is this happening?


A month ago, these pages looked at the flooding issues on the road next to the proposed Sidford Business Park – and as reported at the time of the planning application, Flooding is now more extensive and, according to the Halcrow Group report (2008), will be worse still by 2025 to the extent that even Flood Zone 2 will become Flood Zone 3a. Surface water flows down the hills, across the proposed access road and across the field like a river.

Meanwhile, ‘storm drain issues’ on Woolbrook Road have been getting worse – with questions raised a decade and a half ago that further development would further increase flooding on roads.

Sidmouth floods (2) © Anthony Vosper :: Geograph Britain and Ireland taken 2012

Meanwhile, some four years ago, the county council submitted a planning application for a flood alleviation scheme comprising a drainage swale and grassed amphitheatre designed to attenuate surface water runoff and provide a venue for public events – and so to great fanfare three years later the ‘Knowle amphitheatre’ won an engineering prize, as proudly laid out by the engineers behind it. However, an alternative narrative has emerged: “Sidmouth is lumbered with an impressive white elephant that has set back the biodiversity of a locally important site for years.  It would have been far better and cheaper to use the water meadow as an attenuation lagoon.”



A more serious look at investing in green infrastructure might be a way forward – such as installing reed beds and rain gardens, which would help slow water run-off.

But a major issue is the build-up of river pollution – some of it from farmland. And whilst there are fears that this is making its way down to the beach, much of the run-off from agricultural land is emptying onto roads before it enters drains and the water system. The National Highways website reports on water run off from farmland – and here’s an example of a West Country road still flooded two weeks after storm Babet from last month.