5 ms·
How could they drain it?
by foota 11y ago
How could they drain it?
- hyperion2010 11y agoDig an alternate channel.
- foota 11y agoI'm not sure it would be quite so simple. The article mentions the reason that they can't just open one gate is because the asymmetric draining would be harmful to the dam. It's possible that any sort of adhoc draining would adversely affect the dam. Not to mention quickly building a secure tunnel to handle the water pressure at that depth sounds like no mean feat.
- acveilleux 11y agoThat's called a spillway BTW and the problem with spillways is erosion and the energy of the water. So spillways have to be made of reinforced concrete or similarly strong materials when the local rock isn't hard enough and they have to be shaped to dissipate the energy. The spillway of the Mosul dam is made of concrete the problem with it appears to be that it allows too high a water level for the dam in its current shape even when fully open.
- techdragon 11y agoI would imagine siphoning might be a simple enough process and could be setup in multiple places along the dam to avoid the asymmetric draining issues mentioned further in the discussion here on hacker news.
- tim333 11y agoYou can syphon up about 30ft. The dam is 371 ft.
- Blaque 11y agoCan you explain why a syphon won't work over 30ft?
- Errsher 11y ago"This siphon effect relies on atmospheric pressure to allow the pressure and pressure potential energy to drop as the water travels upward inside the sealed pipe. But eventually the pressure of the rising water reaches zero and no further reductions in pressure and pressure potential energy are possible. That failure of the siphon effect occurs when the water is about 30 feet (10 meters) above the higher container. You can't use a siphon to lift water higher than 30 feet because above that height, an empty region will develop at the top of the pipe and stop the siphon process." http://www.physicscentral.com/experiment/askaphysicist/physics-answer.cfm?uid=20080512104921 http://www.physicscentral.com/experiment/askaphysicist/physi...
- mikecb 11y agoWhat about running the tube over the dam and down to a lower level than it originates? Then gravity(?) does the trick?
- sangnoir 11y agoIt would only work if the difference between the water level and the top of the wall is less than rouhgly 30ft (as per xkcd). The bottom line is, the siphon will not work if it has a vertical water column taller than 30ft (water weight per unit area becomes greater than opposing atmospheric pressure)
- taco_emoji 11y agoThe issue is that top of the dam is (way) over 30 feet above the water level behind the dam, which prevents the suction from overcoming gravity. A siphon won't work with that much of a rise in the middle no matter what the difference is between the elevations of the ends of the tube. Also what you're describing is literally how all siphons must work--you can't siphon to a higher elevation.
- 11y ago
- techdragon 11y agoPutting aside the obvious detail that the dam would be empty already if we were trying to siphon water up a full 371 feet... Your correct, the entire thread this spawned was educational, and I learned something new today which was pretty damn interesting. Interesting enough I'm not bothered by the small karma loss my initial comment incurred.
- tizzdogg 11y agoWhy not use pumps instead of syphoning?
- foota 11y agoActually though, you could presumably cut holes in the dam as you go. So siphon off the top 30ft, then cut a hole at 341 feet and siphon through there.