Hi Brian! Just one more tidbit of thought - I recently watched a Discovery
channel program on the 3 Gorges Dam project and there is significant
concern on what would/could/should happen if an earthquake shifts the
fault line which is the base of the Gorge itself. We may get to witness
(unfortunately) if the margin of safety used by the construction engineers
is adequate for the potential impact of a natural phenomena.
Dave Hillman
Rockwell Collins
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Brian Ellis <[log in to unmask]>@ipc.org> on 01/21/2002 10:26:44 AM
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Subject: Re: [EN] Three Gorges Dam
Yes, Joe, it is controversial. The thing that worries me is that China
has already lost a number of persons, the figure varying from 75,000 to
200,000 according to the source, from two modern hydroelectric dams
overflowing, due to natural phenomena, plus other relatively minor ones.
The three gorges, after which it is named, are a geological fault line
which cracked an overlying, very friable, limestone rock and erosion did
the rest. While I was there, I photographed a minor landslide falling
into the river. With the extra weight of the retention lake bearing on
the rocks (estimated at 60 billion tonnes), anything can happen, in my
opinion. It would not require more than a medium-sized collapse of a
mountainside into the lake (and there is plenty of evidence of such
collapsing having occurred in the past) to send a massive wave
downstream, channeled by the gorge walls, causing an overspill (as has
happened elsewhere). The city of Yichiang, with 2 million inhabitants,
is just 20 km downstream and there is no way that they could evacuate in
the time that an overspill reached the city. If the dam itself gave way
completely (and don't tell me that this has never happened!), then the
damage downstream would be immeasurable, possibly all the way to the
sea, 1,000 km away.
I pray that this pessimistic scenario will not happen, but ... it would
not be the first time, although never on this scale before.
Best regards,
Brian
Joseph Fjelstad wrote:
>
> Hi Brian,
>
> I just returned from Hong Kong and on my next trip will be visiting
> Guilin. The world is poised to loose one of its most beautiful visual
> treasures due to this controversial and risky venture. Many suggest
> that this is a battle with nature that cannot be won. We can only
> hope...
>
> Very best,
> Joe
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