FLOODING IN DUBLIN - RIVER DODDER

Dublin City Council Report on the Extreme Flooding of 24th October 2011.


Flooding Related to the River Dodder

Of all the major rivers in Dublin the river Dodder falls the greatest height over the shortest distance. It rises on the slopes of Kippure mountain and descends through a distance of 26km to discharge into the River Liffey near Ringsend. The swift transfer of rainfall into the river channel combined with the high degree of urbanisation within the catchment downstream of Bohernabreena makes the river system highly susceptible to flooding during
periods of extreme rainfall events. Current estimates indicate that the peak volume of water which flowed through the River Dodder during the most recent flooding event was approximately 250m3/sec downstream of Ballsbridge.

The majority of flooding in the Dodder catchment resulted from the river overtopping its banks and flooding areas that had been historically flood plains. While isolated flooding reports were received in the Dartry Road and Milltown areas, the greatest number of flooding reports was received from the Stillorgan Road in Donnybrook to Newbridge (Lansdowne Road Bridge). The river is tidal from upstream of Ballsbridge and for the remainder of its course to where it discharges into the Liffey at Ringsend.

The current estimate of premises flooded within the Dodder catchment stands at 192 dwellings in addition to 136 other buildings/non-residential ground floor units.

The principal locations where property flooding occurred as a result of the Dodder River were as follows:

Marian College (swimming pool and residential building)
Canon Place (12 Properties)
Herbert Road (1 Property)
Railway Cottages (15 Properties)
AVIVA stadium car park and grounds
Sweepstakes site (130 Properties)
Ballsbridge Park (The car parks of three apartment blocks)
Herbert Cottages (26 Properties)
Ballsbridge Avenue (18 Properties)
Dodder View Cottages (43 Properties)
Beatty’s Avenue (8 Properties)
Granite Place (1 Property)
Main RDS building (15% of the floor area)
Anglesea Road, Dunluce, Somerset (54 Properties, cricket club pavilion)
Licensed Vintners Association (Basement and wall collapse)
Junction of Anglesea Road and Simmonscourt Road -The Church of Ireland near the junction was also flooded
Leinster Rugby Ground
Bective Rangers Ground
Old Wesley Ground
Bective Tennis Courts
Eglington Road (3 back gardens)
Clonskeagh (Public House)
Strand Terrace (5 Properties)
The Dropping Well Public House
Dartry Cottages (4 Properties)


Tide Gates:
There are three tidal flood gates located at Londonbridge Road, Lansdowne Village and Newbridge Avenue and two demountable flood barriers located on the Aviva Stadium side of the river. These were designed to protect local areas against tidal flooding events. On the night of 24th October the predicted tide level was below that which necessitated closure of these units.

Following reports on the night of rising river levels a decision was taken to activate these defences. The gates were closed at approximately 10pm and the demountable flood barriers were erected approximately half an hour later.

There was a delay in closing the tidal flood gates as difficulties were encountered in retrieving the locking pins which were stored in a kiosk adjacent to the Aviva Stadium. The Drainage Division has reviewed the protocol for closure of these gates and will in future be closing the gates on foot of both tidal and pluvial adverse weather forecasts subject to staff availability. This warning will correspond roughly to a yellow Tidewatch Report.