Saving the Dead Sea

Nice little piece here about attempts to fill up the Dead Sea from the Red Sea. Most of it\’s pretty good actually, it is something of a worry and yes, the best solution would probably be to abstract less water from the Jordan. However, it being The Guardian they can\’t help themselves but snarl at business:

The company is only concerned with its commercial interests, he claims, and whether a change in the chemical composition of Dead Sea waters would impact on its mineral extraction business – which has been a big contributor to the problem.

Really?

Industry is also to blame: the waters of the Dead Sea have been pumped into evaporation ponds to allow the extraction of minerals.

I\’m not entirely convinced by that. Perhaps I need someone to put me straight here?

You can get all sorts of minerals from salty water. Obviously, with sea salt we can get sodium chloride as with Maldon salt. However, if you\’ve got a really briny piece of water, like the Dead Sea, when you evaporate off the water you can get commercial quantities of magnesium (magnesium chloride I assume) and that\’s what that plant does.

OK. But I\’m unconvinced that evaporation ponds actually increase the amount of evaporation. They certainly make it possible to collect the salts (the technical name for things like magnesium or sodium chloride) as once the water evaporates off you\’ve got the salt just lying there. If water was evaporating off the top of the sea at the same rate then the salts would just be making the rest of the sea that little bit saltier.

OK, maybe the evaporation ponds increase the surface area of the sea and thus the amount of evaporation that occurs. But, perhaps someone can tell me, is this actually a serious addition to the evaporation of the sea?

5 thoughts on “Saving the Dead Sea”

  1. The water level of the dead Sea has been falling, as you say largely due to extraction of water from the river Jordan.
    This means the surface area has been reduced, because it exposed large areas of land which had been very shallow water before; the promontory called Al-Lisan (“the tongue”) which once was a short one on the Jordanian side is now nearly cutting the sea in two.
    So the evaporation ponds may be increasing evaporaton, but not as much as the reduction in evaporation caused by this lowering of the sea level.
    Personally I’d say the Sea is more value for tourism than mineral extraction, but the two can exist side by side.

  2. Jim: The evaporation ponds are providing a fixed level of outflow from the Sea to evaporation, assuming that they aren’t being progressively shut down to conserve the water level. So if we suppose the Sea started in a steady state, then the Sea’s level will decline to a point where the total reduction in natural evaporative losses equals the losses from the evaporation ponds. The question is how big the effect is.

    Tim: The UN claims, in an undated report, that evaporation ponds account for 25%-30% of evaporative losses from the Sea [1].

    What happens to the level depends very much on the profile of the Sea’s bed, as Jim and The Englishman suggest. I dug up a very good paper by Al-Khlaifat [2], who deals with a lot of this stuff properly. (I.e., he wasn’t published by the Grauniad.)

    [1] http://www.grid.unep.ch/activities/global_change/deadsea.php
    [2] http://www.scipub.org/fulltext/ajas/ajas58934-942.pdf

  3. A couple of things we need to remember:

    Firstly, the Dead Sea got very salty thanks to an inflow of minerals in solution being concentrated by evaporation. Increasing salinity is in fact the Sea’s natural state of balance.

    Secondly, salt ponds may increase the rate of evaporation (indeed one would hope so since efficient seperation of water and salt is what they are designed to do). But after the water is gone, someone usually comes along and loads all the exposed salt crystals into big sacks and takes them away. My guess is that the effect of the salt works is actually quite close to saline neutral or not much more saline positive than the natural evaproation process which doesn’t remove any salt.

    Which brings us back to only one possible culprit for any dramatic increase in Dead Sea salinity – excessive water extraction from the Jordan Valley.

  4. The Guardian article talks of a plan to pump water to the Dead Sea. Rather an interesting idea as gravity could do the job perfectly. In fact I thouht the original project was to place a turbine on the end of the pipe to take advantage of the fact that the Dead Sae is so far below sea level.

Leave a Reply

Your email address will not be published. Required fields are marked *