The extent of flooding that occurred in Listowel last November is unlikely to happen again for another 150 years.
That’s according to MWP Ireland engineering consultants who were commissioned by Kerry County Council to investigate the flood which hit parts of Listowel and the surrounding area on November 23rd last year.
The consultants recommend an early warning system be installed as a short-term mitigation.
They say a flow gauge at an appropriate upstream location on the River Feale would give an advance warning of rising water levels.
One hundred and eleven residential properties in Listowel, Killocrim and Gortnaminch were flooded on November 23rd last during Storm Bert.
MWP Ireland consultants said snowfall the previous week, combined with rain from Storm Bert, resulted in the volume of runoff - the combination of moderate rainfall and rapid snowmelt is rare in Ireland.
At one stage on November 23rd, the water level in the River Feale was more than 18 metres above the mean sea level, exceeding by over 700 mm the previous highest flood level recorded in 1973 in Listowel.
The water level rose by almost one metre in just over eight hours that day.
The consultants said the return of a flood of similar magnitude would likely be in the range of 90 to 160 years; most likely in the order of 150.
MWP Ireland said fluvial flooding – when the capacity of a river channel is exceeded and water flows on the adjacent land or flood plain – was the primary factor.
They said there were no reports of flood defence embankment failures at Listowel or Killocrim.
They found that embankments along the northern bank of the Feale near Listowel Bridge overtopped but that the extent of flooding in Listowel town was not significantly influenced by bridge capacity.
MWP consultants propose several short-term measures including topping up of embankments at Killocrim, and enhancing Listowel town park embankments along with a ramp on the access road.
They recommend that the design of long-term measures is progressed as part of a flood relief scheme.
They ruled out dredging of the River Feale, they said it’s crucial that the implementation of flood mitigation measures does not adversely impact ecological conditions.
