Fred99:UncleArk:Fred99: I see The Press is quoting the CCC now calling it a "100 year event".
I doubt it - the impact might be one in 100 year, but that's because some land had sunk, stormwater systems are damaged etc.
Describing the storm event as a 100yr event is simply a a function of event duration and rainfall intensity measured in mm/h.
In other words, the amount of rain that has fallen in ChCh per hour over the last 24 hours is the equivalent of an event which has an annualised probability of occuring being 1% (or 1 in 100).
In actuality at times the storm event was about a 120yr return period event.
Not according to data I'm looking at.
Just over 70mm of rain in 48 hours. Highest in 1 hour was 4.8mm.
It was nothing out of the ordinary - only slightly above mean annual recorded maximums.
See page 7.
See also page 20, where in 1986 floods, more rainfall was recorded in 24 hours (Chch Gardens) than the 48 hour recording for this latest event.
I don't believe it was a "100 year event" at all.
Since you mention the Botanic Gardens site.... I can report that site 325616 (ChCh Botanical Gardens) logged 141.2mm in 1440 minutes (24 hours) for the 24 hour period ending 9:05am 5th March. The data logging interval was 5 minutes.
This is equivalent to 5.88mm/h over 24 hours equivalent to a return period of 119.9 years.