Whose bright idea was it to drain the Sichuan Quake-lake?

Question

Anyone can see that the landslide barrier (475metres broad and 150meters high) will never burst. If they'd left well alone, the worst that would've happened if the lake overflowed, would've been a slow washing down via channels gravity would provide.

Nown they've bulldozed and blasted a huge artificial channel, leaving a frail barrier on the upside. If that goes, the rush of water will be catastrophic. Probably won't be reported, of course.

Answer 1

You are confusing the size of the natural dam with its stability.  

Also, engineered dams have a "spillway", to deal with overflow safely.  In an earthquake dam, once it overflows, the flow will very rapidly (not slowly as you think)  wash the dam away, leading to a catastrophic flood.

Did you never build dams as a kid?  You would have observed this stuff.

Answer 2

Well, you need to go learn about the frailty of landslide dams. There have been some real disasters - one I have been around occurred in Yellowstone Park.   If it had overflowed, the erosion on the downside would have weakened it rapidly.   The "dam" is not consolidated but is wet soggy earth so it will leak and weaken.   Your confidence that is it functional is misplaced.  And while they have removed a lot of earth, compared to the amount in the dam, it is small and they should be able to allow the water to lower gradually but faster than the rains are filling the dam.   Think of it as putting a giant suction pipe in place over the dam, without the pipe.

Answer 3

The downstreamers who don't want cubic miles of water to gush at them.

Answer 4

Never seem the failure of an earth dam have you?

When the water o'ertops the dam, the failure is

typically quick and dramatic.

Better the smaller flood now than a catastrophic

one later.

They do know what they're doing.

You don't know what you're talking.