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Draining California

nationalgeographic.com

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Re: Draining California

#71

Post by tanzam75 »

mrbabbage wrote: post #70
tanzam75 wrote: post #54

Earlier quoted context omitted.

That's non-metric thinking. In the metric system, you could simply use the cubic meter. A hectare is 10000 square meters. A centimeter is 0.01 meters. Thus, if 1 centimeter of rain falls on a 1 hectare field, then that's simply 100 cubic meters of water. The nice thing about this is that you can easily compare quantities from different contexts. A cubic meter is a cubic meter, whether the water came from a pipe or fr…

> It's not just water. Look at HVAC. In the US, natural gas is billed in therms, and electricity is billed in kilowatt-hours. In metric countries, both electricity and natural gas are specified in kilowatt-hours. It's funny you use that example, because kWh are silly, unnecessarily convoluted units themselves :-) the "proper" unit for this dimension is the joule, and 1 kWh = 3.6 MJ (1000 J/s ∙ 1 hr ∙ 3600 s / hr ∙ 1…

> There actually is, however, some value in having different units for methane vs electricity, since you have to run methane through a suboptimal furnace to harness its energy. Granted, modern gas-powered furnaces are usually more than 90% efficient, but there's still some loss.

Well, heat pumps transfer more than 1 kWh of heat transfer for every kWh of electricity. You have to account for the performance factor anyway, whether you're using natural gas or electricity.

The point is that, once you've divided by COP or AFUE, you get price per effective kWh, which you can then compare directly. As opposed to getting a price per therm, which you must apply a conversion factor to.

With cogen, you get both electricity and heating out of the unit. If it's all in kilowatt-hours, then you simply add them up and compare to the kWh of the incoming natural gas to get efficiency. But how does a therm of electricity translate to volts and amps?

As for the kilowatt-hour, I think the reason we don't use megajoules is that metric time never took hold. If we had metric hours, minutes, and seconds, then the kilowatt-hour would be as awkward as the hectare-centimeter.

Re: Draining California

#72

Post by aurelian »

palderson wrote: post #56

Big problems, create big opportunities. Some of the developments that may occur to address this issue over the next 10+ years: - Development of a robust water entitlement exchange - Decoupling a water right from the land to create a more tradable asset - Regulation change to allow for water leases - A shift away from growing 'thirsty' crops in drought-prone regions - Decentralization of water treatment plants to redu…

Why would state sponsored overseas farming of thirsty crops for US import be desirable?

Re: Draining California

#74

Post by ikawe »

snomad wrote: post #34

Many people will often say agricultural uses 80% of the water. This is not the whole picture. "Nature provides about 200 million acre-feet of precipitation to California in average years. Of this total, 65% is lost through evaporation and transpiration by trees and other plants. The remaining 35% stays in the state’s system as runoff. More than 30% of this runoff flows out to the Pacific Ocean or other salt sinks. Th…

I've been scraping aqueduct sensor levels from the LA Aqueduct for a couple of years - aggregating the data here: http://api.thirsty.la/

Please let me know if you find it useful!

Re: Draining California

#75

Post by aurelian »

ilaksh wrote: post #67

Strategies like desalination (see San Diego's new huge desalination project), hydroponics/aquaponics and (ultra)local production can make these problems more manageable. Instead of giant agricultural fields that are open to evaporation, hydroponic or aquaponics inside of greenhouses could vastly reduce water usage. Instead of huge farms or corporations producing food tens or hundreds of miles away from where it is ea…

Why do you think local food production would be more efficient? My gardening projects have been case studies in inefficiency.

Re: Draining California

#76

Post by ilaksh »

aurelian wrote: post #75
ilaksh wrote: post #67

Strategies like desalination (see San Diego's new huge desalination project), hydroponics/aquaponics and (ultra)local production can make these problems more manageable. Instead of giant agricultural fields that are open to evaporation, hydroponic or aquaponics inside of greenhouses could vastly reduce water usage. Instead of huge farms or corporations producing food tens or hundreds of miles away from where it is ea…

Why do you think local food production would be more efficient? My gardening projects have been case studies in inefficiency.

http://en.wikipedia.org/wiki/Local_food

When I think of local food production personally I am envisioning taking advantage of the latest in technology in order to create the most efficient and self-sufficient process possible. For now that means things like hydroponics and aquaponics. In the future that could be more sophisticated biotechnology or nanotechnology of some sort.

Its sort of a localization and distribution mindset.

One basic idea is that if food is produced far away, as it is often produced hundred or thousands of miles away, some energy must be expended to transport it. So if a tomato grows hydroponically in the corner of the room, the distance it needs to travel to my mouth in order for me to eat it may be say 10 feet. If it grows in the ground 500 miles away, it would need to travel 500 miles (plus 10 feet). Certainly the energy required to move a tomato 500 miles is greater than zero. Add that up for everything you eat, and there is a fair amount of inefficiency.

Another idea is that producing food or other needs locally means less dependence on more centralized control and distribution systems, which means more security for individuals and families. Its sort of like extending the idea of solar panels and 3d printing. If we can get our own energy from the sun, and print out our own products, why do we have to go to the store to buy food that was grown 400 or 4000 miles away?

Re: Draining California

#77

Post by ghshephard »

hughdbrown wrote: post #64
ghshephard wrote: post #55

Earlier quoted context omitted.

No argument from me on any of that, totally makes sense. And thanks for the correction of 70,000 m^3 -> 70,000 * 1000 m^3 for Crystal Spring Reservoir. (I'll admit to having to have Soulver up just to have this conversation - Metric system would make it way, way easier.)

So when you hear 70 000 cubic meters, try to visualize it: 1.4m deep by 50m long by 25m (1750 cubic meters) is about an Olympic swimming pool. So we would be talking about a reservoir made up of 40 Olympic swimming pools, and then we'd say, "Hey, that seems pretty small for a reservoir." Maybe when wikipedia says that the reservoir is 57,910 acre-feet you have a sense of what that would look like, but I have absolute…

I still prefer Metric, but, I have a very good sense of what an acre, 10 acres, and 640 acres are (I have family that farms, and a "section (640 acres)" is a pretty common unit of measurement.

57,910 acre feet would actually be more "intuitive" to me than 70,000 cubic meters (though much harder for me to do calculations and almost impossible to do unit shifting).

57,910 acre feet is roughly 100' deep of water on a section of land. I can "visualize" what that reservoir would would like.

Or, for more practical/relevant to irrigation purposes, it's 100 sections of land, 1' deep.

But yes, I'm still going to argue for the metric system. I promise.

Re: Draining California

#78

Post by Roboprog »

Shivetya wrote: post #63
snomad wrote: post #34

Many people will often say agricultural uses 80% of the water. This is not the whole picture. "Nature provides about 200 million acre-feet of precipitation to California in average years. Of this total, 65% is lost through evaporation and transpiration by trees and other plants. The remaining 35% stays in the state’s system as runoff. More than 30% of this runoff flows out to the Pacific Ocean or other salt sinks. Th…

it is self inflicted by the US Government. Why? Because they over subsidized the water being sold there, so the cost of the water was so low that wasteful practices and water needy crops became the norm because it was more than affordable, it was nearly a give away.

It should be cheap during the years there is a lot of it, but perhaps not during drought years.

Re: Draining California

#79

Post by Roboprog »

gregwebs wrote: post #46

What a great visualization! It is sad though to click on the other tab "When Snows Fall" and see the central valley referred to as an "inhabited desert". We continually try to give the impression that we turned the Central Valley from desert into farmland, when the opposite is the case: we turned what was a winter wetlands into a desert. http://en.wikipedia.org/wiki/Great_Valley_Grasslands_State_P...

As somebody who has lived all but about 4 years of his life in the Central Valley, it sure feels like a desert in the summer time (and late spring, and early fall) any where there is not active irrigation.

True, it's not Mojave or the Sahara, but it's pretty hot and dry. Savanna a la Africa is not a bad comparison.

Re: Draining California

#80

Post by Roboprog »

Irony: it has been horribly dry this year. However, it just started raining (with a huge side of lightening) a few minutes ago in western El Dorado county, a few miles from Folsom reservoir, where I live. Normally we don't get rain until October or later. Remains to be seen if it does more than slicken the sidewalk, though.
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