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Lake Death Valley

Use altitude difference to drive desalinator
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[Scottinmn] scared me into posting this idea, as he was getting perilously near with the Caspian scheme.

Death valley is about 200 feet lower than sea level. Construct a pipe from the ocean to death valley, full of fresh water. It would act as a giant siphon. On the ocean side, at the pipe entrance place a semipermeable membrane which exculdes ions. Filters of this sort are used in reverse osmosis desalinators. The gravitational energy from the siphon would be enough to pull water through the filter.

A medium size pipe would allow irrigation and productive cultivation of Death valley. Larger pipes would alow conversion of the entire area to a freshwater lake, which could serve the Los Angeles area.

Originally this idea was for a similar sub sealevel desert in Libya, but this has two problems. 1: we would have to take over Libya (maybe after Iraq) 2: I think the resulting salinization of the Mediterranean would be hard on it. That amount of extra salt would be nothing to the Pacific.

bungston, Oct 06 2002

reverse osmosis http://urila.tripod.com/
[stupop, Oct 07 2002, last modified Oct 06 2004]

(?) Soil Erosion http://www.sit.wisc...hightower/soil.html
Effects of Soil Erosion [countzero, Oct 05 2004, last modified Oct 06 2004]

Land below sea level http://geology.com/below-sea-level/
[ldischler, Dec 28 2009]

Solar ponds http://en.wikipedia.org/wiki/Solar_pond
[oxen crossing, Dec 28 2009]

[link]






       Hmm, how well do those semi-permeable membranes work? I mean, I can believe they do this in a lab; would they wear out after processing several billions gallons though? And can they handle gushing water, or just drops at a time? If the rate is too slow it will just evaporate too quickly on the other end. Also note that we're talking about a very long pipe here going through lots of mountains. For closer, flatter depression areas (Salton Sea, central Lybia, Dead Sea) this sounds more feasible.
scottinmn, Oct 07 2002
  

       //we would have to take over Libya//   

       Wow, the halfbakery ahs an army now? Who'd of thunk it.
[ sctld ], Oct 07 2002
  

       Simpler:   

       Use the difference in height to drive turbines situated at the Death Valley end of the Big Pipe.   

       Feed the water into solar stills. Use the abundant solar energy to produce fresh water. Put this into greenhouses. Grow giant vegetables.   

       Take the resulting dense brine and pump it back seawards, using a fraction of the energy mechanically cupled through from the turbines. Dry some salt completely, put it into bags and sell it. It can be trasported on an electric-powered railway run from the turbines. That can take the vegetables, too. Sell the spare electric power to run the air conditioning of the poor sods who have to live there and maintain the equipment .....
8th of 7, Oct 07 2002
  

       Hey look who added that link!
blissmiss, Oct 07 2002
  

       Don't desalinate, just use a million solar pumps to pump salt water into the uninhabitable deserts. You wouldn't want to do this where people do rely on the water table (the greater Mojave Desert) but turn Death Valley into a giant evaporator. Nature will return that water somewhere useful.
ubergoober, Sep 27 2003
  

       Also, this lake would up the ahumidity in the air causing great rains in an area without vegetation to stabilize the soil. Floods of ruinous scale may be a result of this "man playing god" idea.
the rooster, Sep 27 2003
  

       [ubergoober] - I imagine some extra salt in Death Valley would not do much harm. It is full of evaporated salts as it is. The water sure as heck would evaporate, too. If there were great rains in Death Valley, I cannot see that doing too much harm. Outside of death valley they might permit cultivation with less irrigation.
bungston, Sep 28 2003
  

       [the rooster] - Also, these rains would cause much soil erosion down stream. Possible floods could remove topsoil where they occured. More info on soil erosion in link.
countzero, Sep 29 2003
  

       There certainly are now... any non-aquatic inhabitant of Death Valley, for a start.
david_scothern, Jun 11 2004
  

       On thinking more about this idea, pouring fresh water onto the ground in Death Valley is a bad idea. The ground is very salty there from the old lakes that dried up. I think collecting the fresh water and using it for irrigation makes more sense. I envision not croplands, but residential area. People seem enamored of living in the desert and playing golf.
bungston, Aug 08 2007
  

       Too bad 'Dead Sea' is already taken.
whozwat, Aug 11 2007
  

       // It would act as a giant siphon. // No it wouldn't. Not unless there were no hills more than 32 feet high between the two ends of the siphon. Bas science.
MaxwellBuchanan, Aug 11 2007
  

       //(maybe after Iraq)//   

       How wonderful is hindsight...
d, Aug 11 2007
  

       Another benefit of refilling our land locked former seas with ocean water is C02 absorbtion. Just consider all the benefits: =>drawing off global warming induced excess sea height, =>green energy generation, =>fresh water production, =>temperature moderation, =>population dispersion from crowded coasts, =>C02 absorbtion. Any others?
whozwat, Aug 20 2007
  

       But what about the pupfish?
swimswim, Dec 28 2009
  

       Don't desalinate it, let it be salty, and use it to generate vast amounts of electricity, using solar salt pond technology (basically temperature differences in the depths of the water drive heat pump generators, if I remember correctly)(see link for more and correct info)
oxen crossing, Dec 28 2009
  

       Could you have a bit of both? Build a bank in the middle, desalinate one half and stick the salt in the other.
nineteenthly, Dec 28 2009
  

       32.4 feet.
WcW, Dec 28 2009
  

       //// It would act as a giant siphon. // No it wouldn't. Not unless there were no hills more than 32 feet high between the two ends of the siphon.//   

       That isn't quite correct.
You mean "no hills more than 32 feet above sea-level".
  

       If there are any, they could be tunneled through, of course.
Loris, Oct 02 2010
  

       Has anyone wondered why Death Valley is dry in the first place? I don't think it got a leak that we fixed, or anything.
Boomershine, Oct 02 2010
  
      
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