On Tue, 23 Mar 2021 09:30:46 +0100, Mike scribed:
> MELBOURNE — Heavy rains along Australia’s east coast over the weekend
> have brought the worst flooding in half a century in some areas,
> authorities said on Sunday, forcing thousands to evacuate and damaging
> hundreds of houses.
Nah, the half a century is just a statistical probability. All the ares
affected have been flooded multiple times in the last 50 years.
>
> New South Wales Premier Gladys Berejiklian said the downpour across the
> state, Australia’s most populous with 8 million people, was worse than
> initially expected, especially for low- lying areas in Sydney’s
> northwest.
Actually, the flooding starts in the west through to the northwest.
Plus there is a pile of flooding all the way up the east coast of NSW
into Queensland.
Note, the flooding along the North Coast is considered worse than the
Sydney flooding at 1:100 years.
For Sydney, the problem has really been that the rainfall has been over a
wide area and all the area mostly drains to one river; the Hawksbury
which has tributaries coming in along almost its entire length.
This is a god map showing the catchment and dams, which are all full*.
https://www.waternsw.com.au/supply/Greater-Sydney/greater-sydneys-dam-
levels
Note: Prospect Dam is a reservoir, not a dam. Water is pumped from
Warragamba Dam(the big one) and it supplies most of the Sydney area water
supply. The dam system is full, excapt for two coastal, isolated Dam,
neither of which would have had any effect on anything but very local
flooding.