THE ISSUE OF flooding in Dublin city is back in the spotlight, after a number of flash flooding incidents in recent weeks. Thankfully, it was nowhere near as bad as the 2011 floods, in which two people lost their lives.

However, properties all over the city were flooded – particularly basement flats. Businesses were also left counting the cost of damage to premises: staff at Clerys Department Store were told this week that they may not be back at work for months, after sustained heavy rain on the night of 24 July caused part of the roof to cave-in.

Executive Manager with Dublin City Council’s Water Services division Tom Leahy says the city has been experiencing “monster rain” events of incredible intensity in recent years – rainfall amounts Dublin’s drainage system just wasn’t built to cope with. He told TheJournal.ie:

Normal rainfall you get the equivalent of maybe a half inch, quarter inch, three-quarters of an inch. But if you look at it in five minute intervals you would normally expect an average rainstorm to be about .2, .3 of a millimetre per five minute period.

An absolutely intense rainfall burst could get up to about .6 to .8 millimetres per five minute period.

The intensities that we’ve been getting in the last week or so have gone up to eight millimetres for a five minute period. In other words ten to twenty times more than the maximum we have ever experienced in Dublin.

In the usual course of events, warnings go out across the media from the likes of Met Éireann, the gardaí and the Road Safety Authority when heavy rainfall’s expected in any part of the country. But the problem is predicting just how intense the cloud-bursts will be in any given area.

Pilot scheme

The council’s prioritising getting early warnings out to householders and businesses in vulnerable areas, and Leahy says they’re now working with IBM to see if their forecasting model ‘Deep Thunder’ could be of use here. The research project – part of the tech giant’s Deep Computing initiative that also produced the Deep Blue chess computer – aims to provide local high-resolution weather predictions, and grew out of a project to provide accurate weather forecasts for the Atlanta Olympic Games in 1996.

Pilot ‘Deep Thunder’ schemes are already in place in New York state and in Rio, and Leahy says Dublin could become just the third city in the world to make use of the system:

At the moment Met Éireann just can’t tell you when the thunder storms will come, where they will come and at what time or what time or in what intensity. It’s beyond science at the moment.

So this is a research tool and it’s a modelling tool, but it does offer us the possibility that we may at some stage in the future be able to have more accurate forecasting.

You can check out how Deep Thunder works in the video below…

Read: Clerys staff told it may be months before store re-opens

Pictures: Clean up under way after floods hit Dublin and Cork