As I understand it, we are consuming fresh water at a rate twelve times greater that it is replenished by precipitation which also has the effect of making previously permeable aquifers impermeable leading to flash floods, etc. Since this is clearly unsustainable, is there anything that can be done about it?
Nuking L.A. would be a start. I know that sounds flippant, but it’s an unsustainable megalopolis living on mostly stolen water. The farms in California are also culprits.
There huge numbers of procedures we can use to massively reduce water consumptions. Proven technology like subsurface irrigation, water efficient varieties, soil monitoring and so forth.
These things aren’t being done at the moment because there is no incentive. Water remains so cheap as to be almost free. As water becomes more scarce and more valuable, the technologies will become more appealing.
It would probably be preferable to implement these solutions before water becomes physically scarce, but that isn’t going to happen for fairly obvious reasons.
To be fair, you need to include much of the American Southwest and the Central Plateau. So much water is siphoned out of the Colorado River that it doesn’t reach the Gulf of California anymore.
Given Cecil’s column last Friday, I don’t know that we have the extra capacity to desalinate the volumes of water currently used and pump it thousands of miles uphill. Also, if I wanted to kill people, I could just let the water run out. I would like to know the viability of Blake’s suggestions, though.
I’m not certain where the “twelve times” factor comes from or what aquifer system it applies to, but there are several aquifers, such as the Ogallala aquifer that supports much groundwater irrigated agriculture in the American Midwest and Central South, have very slow refresh rates and contain water dating back from the Pleistocene. The rate at which we consume this water is hundreds of times this natural replenishment rate. Aquifers once drained will compactify and subside, rendering less volume of water than can be stored, but this doesn’t exacerbate flash flooding, which is purely a surface topology effect. Flash floods occur even in highly permeable soil in deserts, and no subsurface aquifer can replenish fast enough to absorb a rapid flux of surface water.
While given a technomagical infinite energy source we could desalinate seawater, there remains delivering it to the areas necessary to support agriculture and industry, which are general not adjacent to the ocean and are frequently hundreds of feet above sea level. This may seem like a trivial problem–after all, we pump, refine, and transport petroleum products–until you start running some first order calculations on the shear mass of water necessary to be moved, and the work needed to be performed to do it. Try multiplying the population of the United States by the several couple of thousand liters of indirect water consumption per day (in addition to that used for bathing, drinking, and cooking) and you’ll realize that the scale of this effort would be beyond comprehension. We currently get all this movement (as well as desalination and filtration) for free thanks to the hydrologic cycle at is driven by solar radiation, which dwarfs current human energy production, a fact grasped only by hydrologists, climate researchers, and some ecologists.
Desalination in mass quantities also has the problem of what to do with the residual material. That may seem trivial, but large concentrations of undilluted salts can be quite toxic and a powerful pollutant, and are corrosive to handle. Just removing them from desalination equipment is problematic (usually requiring more water) and the local environmental effects can be detrimental.
Blake is correct that we could drastically reduce agricultural and industrial water consumption while maintaining or even enhancing yields with only a modest increase in cost, but that that the nearly free price of water makes such efforts unappealing, which is a classic example of the tragedy of the commons. By the time we run low on non-sustainable water supplies it may be too late to implement such measures and still maintain yields. Public awareness and government subsidy or regulation may, unfortunately, be the only means to make growers and manufacturers aware of the need to conserve this resource.
I have always asked the question, why can’t we take water from our reservoirs, use it, purify it and return it to the reservoirs? I’m sure that would be more costly, but it would be basically a closed system, minus the loss due to evaporation.
Simply saying “Make it politically palatable” is equivalent to saying “make a source of clean, cheap energy”. It’s a nice, simple idea, but rather more difficult to execute.
Who do you propose to charge for water? Water is still being used, even if it is not being pumped. So do you propose to charge communities for ecosystem services? Do you propose to charge Mexico? These are some of the more basic problems with water charges.
Agriculture accounts for about 70% of water use. The whole point of applying water to agricultural land is to make it evaporate. In agricultural systems evaporation is always over 75% of the water applied, and if the farmer has any brains at all it is over 95%. The remainder of the water has run over farmland, so is necessarily heavily contaminated with silt, fertiliser, organics and pesticides. You try putting *that *back into a reservoir and you will be shot.
Industry accounts for another ~20% of water use. You don’t want to know what industrial water is contaminated with.
Urban gardens account for another 7% of water use. Once again, >75% is evaporative loss and the rest if even more contaminated than agricultural water.
Urban greywater (showers and sinks) makes up about 1.5% of water use. Did you ever look at the water that runs down your plug holes?
Another 1 % is sewage. The rest is drinking and cooking water. Needless to say they is also contaminated at the stage where you can reclaim them.
So basically, >60% of your water is lost to evaporation. The remainder is so heavily contaminated that even if it could be reclaimed, it would require considerable processing to make it fit to place into a reservoir. The cost of doing that would be much, much higher than the cost of desalination.
river water isn’t fully tapped as a source of water if you you can’t dam it but it’s there. available year-round. run-off at sufficiently high altitude you can tap though dams and aqueducts, farms on or very close to a flood plain can pump river water at a reasonable cost.
rain water collection is another issue that has not been fully explored by cities.
regarding usage, when you are faced with seasonal or intra-day shortages, it doesn’t make much sense to charge more. release less during certain periods of you’re the regulator. individuals and institutions can easily implement their own stocking systems for off-hours. and you don’t have to campaign for more prudent usage. people can figure out how much to use and for what when faced with shortage.
There are not too many rivers in the developed world that are not overexploited.
It’s not a serious option. Cities make up less than 1% of 1% of the land area of the world, so even if we could collect every drop of rain that falls on them, it is literally pissing in the ocean. To make that even less significant, the vast majority of city areas can;t produce usable quality water. Tarmac, lawns, sports fields and so forth all produce water that is heavily contaminated. The only real collection surfaces are rooftops, which make up less than 5% of the 1% of the 1%.
Situations of high variability are precisely when water charges are most effective.
No, not in any way correct.
I really hope this is a joke, but I’m guessing it isn’t.
The idea that a farm or factory can just “figure out how much to use” when a drought hits is ridiculous.
which part of the prudent usage sentence can’t you understand? the given is having less water than what you’d want. so how hard is it to decide how to allocate less?
for three years my family had to live with only four hours of running water a day. no sweat. an overhead storage tank is good for more than two days.
I understand it all, that is what makes it so farcical.
As experience all over the world tells us, it is almost impossible to do equitably, sensibly and without rousing great resentment from multiple groups.
oh, so that’s what he thought. i wasn’t talking about equitable distribution among several users (i thought it’d be impossible for someone to misunderstand.) i’m talking about one user faced the prospect of reduced supply. :rolleyes:
the anecodote is for the part where i said one can easily resort to buffering so that you don’t have to have a balance input-output function of supply and usage which is what many are assuming.
The nature of water is such that there never is only one user.
Nobody is assuming that at all.
The entire thread is contigent upon the fact that water is being consumed at higher rates than it can be replenished over geological timescales. Nothing to do with supply and usage.
i say go ahead and report blakey. your last post didn’t counter anything i said. nature of water indeed. seasonal precipitation hardly fits in any geologicval timescale i know. and the problem of collapsing aquifers due to overdraw it turns out can be remediated. it just takes time, they say.