Mallow has a long history of flooding, principally from the River Blackwater, which flows through the town. There are other watercourses including the Spa Glen Stream which also caused flooding problems, as it flows through the town centre, mostly beneath the streets in a series of culverts.
Major floods have occurred in Mallow in 1853, 1875, 1948, 1969, 1980, 1988, 1995, 1998, 2004, 2008, 2009 and 2010. The most severe flood occurred in 1853 when the town bridge was swept away.
A Flood Relief Scheme was undertaken by the OPW from 2008 to 2010 and comprised of new culverts, walls and embankments, demountable defences, pumping stations and the lowering of ground at Mallow Bridge.
Upon receipt of a warning from the Early Flood Warning System developed by the OPW, Cork County Council staff install demountable defences at required locations to retain the flood waters.
At a cost of €36.7M, the Mallow Flood Relief Scheme has been fully operational for over 5 years and has resulted in:
reduced economic loss to vulnerable traders.
reduced damage to residential and commercial property,
reduced social disruption to the local economy.
reduced disruption and delays to traffic in the town.
Pict. 2.5 Mallow in flood
Pict 2.6 Demountable defense during flood event
A bridge condition survey, undertaken to Eirspan Bridge Management System standards was carried out by Cork County Council between 2012 and 2014. This survey showed a considerable amount of damage to a number of bridge abutments and piers resulting from scour action. Scour is phenomenon whereby the level of the riverbed becomes eroded due to the action of water flow, leading to the exposure of bridge foundations, as shown in Fig.2.1.
Upon receipt of a warning from the Early Flood Warning System developed by the OPW, Cork County Council staff install demountable defences at required locations to retain the flood waters.
Fig 2.1. Bridge Scour at Pier and Abutment [25]