Go with slowing down the flow

SIR – Deputy O’Sullivan is right to question why the flood relief works in Skibbereen did not appear to work as well as hoped during Storm Ellen (Wednesday, August 19th, 2020), but surely concentrating on flood relief works in towns alone is only the start of the process of mitigating flooding which is becoming endemic now in West Cork and other parts of the country.

I have seen little discussion so far in Ireland around mitigation of flooding through active measures in the upriver areas of populated areas such as Skibbereen, Clonakilty and Bandon. It is all very well putting improvements into the natural flow of rivers in the towns themselves, e.g. culverts and raised embankments, but is this not being a little short-sighted?

It must be only half of the solution. If you can slow down the surge of water through these towns during periods of heavy rain, you are helping the natural course of rivers through towns to cope with the added pressure.

When I was living in Longlevens, Gloucester, in 2007 there was catastrophic flooding there in late July that year. The area is built around the Horsbere Brook, which broke its banks in the populated area, flooding many homes in a large housing estate.

The authorities subsequently acquired land on the edge of the city further upriver and turned a field into a flood catchment area by digging a ‘scrape’, which naturally fills with water, right alongside the brook. In heavy rains since then, the built-up area has not flooded as the ‘scrape’ acts as a mechanism to slow down the flow by taking much of the excess volume of water.

This approach has the added benefit of providing some badly-needed prime habitat for wetland birds and mammals. Since its creation there have been sightings of several unusual species which have been attracted to it.

I understand that experts also recommend planting trees in upland areas where rivers rise as this also helps to slow down water flow in times of heavy rains. Another contributory factor to flooding is the increased concreting over of gardens for car parking in urban areas.

In some jurisdictions, it is now mandatory to use permeable materials for newly built driveways which will help natural dispersion of rainwater into the water table below, rather than force it to run off into already overloaded drains and water courses. There seems to be little comment or consideration of these tools to tackle flooding here.

Chris Britton,

Clonakilty.