I don’t know, but here’s a picture of 415 of them flowing through Castleconnell. [Update 13 December: that may be only 405 cumec.]
415 cumecs on 12 December 2015
Actually, a cumec is one cubic metre of water per second, which is roughly one ton per second, which is a lot of water. And 415 cumec is the amount that, according to the blatts, the ESB is currently letting down the original course of the Shannon from Parteen Villa Weir; the minimum flow in that channel, as seen in summer, is 10 cumec.
Castleconnell 12 December 2015
Younger trees getting their feet wet
Who’d have guessed?
Below the bridge
Above the bridge
Stormont
Pump
Sandbags
Sandbag Central
Sandbags filled here for distribution
Army engineers
More equipment arriving
Clonlara 11 December 2015
Ardnacrusha headrace, said to take 400 cumec
Errina bridge on the Plassey-Errina Canal
The stop planks seem to be quite effective …
… as there is little water getting down the canal to Clonlara bridge
Park Canal 9 December 2015
Depth gauge at Park Lock
Lock chamber
Full canal upstream
Irish waterways history 