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| Poulaphouca Lake. © Eugene Brennan |
Water
isn't released directly into the River Liffey south of Ballymore
Eustace from the Poulaphouca reservoir — it's discharged indirectly from the
Poulaphouca dam into a compensatory lake in Ballymore. This acts as a
buffer, protecting the river from huge surges and flooding. Although it's not related to surges on the river, a surge tank adjacent to the Liffey bridge over the gorge on the N81 protects the pipes, or penstocks, that deliver water to the turbines in the generating house from hydraulic shock. The compensatory lake
also creates a pressure head for the Golden Falls hydro station as well as providing an amenity for fishing and water skiing. "The
Flood" on the River Liffey is caused when water is discharged from this
lake through the Golden Falls dam. The Poulaphouca reservoir has been
acting a buffer up until now, holding large quantities of water from
recent rainfall. The lake is fed by both the River Liffey and Kings
River, in addition to some minor streams. However, water levels have
increased by almost 2 metres, requiring water to be released. Since the
Golden Falls lake is also almost full, this means that large quantities water must also be released
from the Golden Falls dam into the Liffey at Ballymore Eustace to allow room for water being discharged from the Poulaphouca lake.
In a recent press release by the ESB, quantities
haven't been specified and they say "there may be a need to pass
through some of these additional inflows over the coming days."
Flows haven't been higher than 33 m³/s (cubic metres per second) in recent years. However, according to the Kilcullen Diary, they were at 55 m³/s in 2000 when a controlled, 24-hour discharge was necessary. this caused floodind in Kilcullen and other regions downstream.
Forecasted
flow for the day, with values at 00:00, 08:00, 18:00 and 24:00 from the
Golden Falls dam is available here on the ESB hydrometric page.
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| Golden Falls dam. © Eugene Brennan |
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