html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> From the archives: I'll let you guess which ones those were.

Monday, April 09, 2007

I'll let you guess which ones those were.

Margie just sent me this. It's a pretty awesome series of pictures of a flight over the American southwest, except for the couple shots that make me want to weep.

Update: She and I just chatted about it.

1. We love that last shot, of the guys. They look exactly like they should.

2. Oooo. Ouch. That shot of Lake Powell, behind Glen Canyon. That is one nasty bathtub ring. It was the first thing I saw. Incidently, should you ever need to pose as one of the water project cognescenti (to impress the fellas at your local bar or to pass yourself off as a technical aid worker when you are really an international spy), that is your number one tip. When you have brought your prospective hook-up out to the canal banks, and he is looking up at you with wide eyes and you know a little dirty talk will close the deal, you hook your fingers into your belt loops and squint at the canal sides. Check out the water stains on the sides of the canal. Is it dark for more than five-six inches above water level? Then use your deep voice of technical expertise and say "Having a little trouble with water level control, I see." If the water level is real close to the top of the stained cement, you just say "Got some nice tight control on that canal. Long-crested weirs?"* He will totally swoon and you can pull him in for a kiss. He'll be your plaything after that.

Anyway, Lake Powell is way down and people are talking about needing more water. A real temptation when you need more water is to build more storage. But the thing laypeople don't necessarily realize about new storage in the west is that there may never be water to put behind it. Lake Powell itself may never be full again, as new demands (like that picture of Vegas sprawl) tax the Colorado River.

Waterstored = (Waterin - Water out)*time

This is not magic. But what many don't realize when they call for new dams is that the amount of water they have to let out (for downstream uses, like irrigation, municipal and in-stream habitat) is, most of the time, all the water in the river.

Waterin = Water out
Waterstored = 0

There isn't much unspoken-for water in our systems now; any river that can be dammed is busy. What you could get from new storage is capture of the occasional flood flows, where so much water comes down that everyone's needs are met and more. That "more" could be tucked away. Last year and the year before, if there had been available storage in California, there would have been lots of water to put behind it. This year, there was none. Most years, there will be no new wet water, because all the flows that are available in an average year are currently put to use. (And if you think that in-stream water use has been shafted for the past half-century, which is not a far-fetched thing to think, those rivers are oversubscribed.)

So when your governor says that we need to consider new storage because of global warming, one important consideration is "store what?" With uncertain new hydrology, new storage capacity may take a very long time to fill. You're counting on rare flood flows to fill that. On the other hand, as global warming models predict warmer storm events with more extreme precipitation, it might be good to have mostly empty dams to catch big events.

My civil engineering professor said that canals move water through space; dams move water through time**. Most of the water behind dams now is legacy water, stored up from a time when it was OK to turn off the downstream river while you were filling your dam. You might also not realize that a very large portion of it is unreachable. The "dead pool" is the water below the bottom of the gates that release the water. Unless you pump it out (expensive), that water can't be moved. When you talk about usable water in a reservoir, you're talking about the portion at the top that can be emptied, released for irrigation in the summer and drawn down to make way for potential flood flows in the fall.

That right there is the classic conflict for dam managers. Irrigators want them to hoard up as much water as possible, in case next year is dry. Flood managers want them to empty down to the dead pool, so they have the ability to catch a flood. For most dams in California, in the 1930's through 60's, the _rmy Crps of _ngnrs calculated a water height that operators must be at on the first day of flood season; they've hit that water height for decades. It is only in the past, say, fifteen years that people have proposed basing the amount of water behind a dam (and thus its capacity to catch floods) on weather predictions for the winter. That is pretty crazy talk, this "keep your reservoir high if it looks like a dry winter and empty it if you're looking at an El NiƱo year"; fine-tuning management at every level, from dam to district to field, has been slow. You would think we'd already be there, but incremental steps like that is where a lot of our new water is going to come from. I'm not flat-out opposed to any new dams. But considering how cheap water has been and how little incentive we've had to optimize its use, I firmly believe that water wrung from our existing system will be cheaper than new storage for another generation or two.









*Should you need more, because the guy whom you know to be a KGB informant is still looking at you all suspicious, look at the distance from the top of the water stain to the top of the canal. If there is almost no distance from the top of the water stain to the top of the canal, you can say "I see you run this thing full. Where d'you put your operational spill?" If there is lots of room (half a foot or so) from the top of the water stain to the top of the cement, you can say "Lots of freeboard in this baby. You must sleep some peaceful nights." Do not forget to hook your fingers through your beltloops.


**The snowpack is the largest reservoir in the state. It stores water over winter, releasing it slowly in the spring. We'll be getting less snow, more rain in a generation or so. The snow line will rise, which is bad news. Low elevations stored more snow because they have more surface area.

17 Comments:

Anonymous Anonymous said...

Big Bear, and Glenn Canyon Dam?

Justin

3:36 PM  
Anonymous Anonymous said...

Oh, I'm guessing the shots of Vegas make Meggie want to cry. Where oh where is all the water coming from? Ok, that's not a tough question, but that's a lot of water usage. Just driving out of Vegas toward Red Rocks has been known to create an irresistable urge to stop for a couple of gallons of water.

-=richard=-

3:59 PM  
Anonymous Anonymous said...

We certainly took a lot of water with us into Red Rocks. I think I carried 4L myself. But, I was smart enough to fill up at the hotel room from the sink for free.

Justin

4:05 PM  
Blogger Megan said...

It was the Vegas shots.

5:27 PM  
Anonymous Anonymous said...

More like "where are all the people coming from". Answer: California. As a native Las Vegas resident, I wish the people that controlled construction here had the balls to stop issuing building permits. We don't have the water for it.

5:33 PM  
Blogger Megan said...

California passed a law that said that developments of 500 houses or more had to show there was water available before they got a building permit. That was thought pretty radical. That came out of a suit between East Bay MUD and a developer from Dougherty Valley. EBMUD said they straight out didn't have the water for 11,000 new houses, and there was a lot of discussion about whether they should be forced to serve the development, and if it was their responsibility to get new supplies if people chose to live in their service area.

Me, I'm with you. I think an evaluation of resource limitations should come first. Don't build houses if there isn't water for them to drink. Don't let people build in floodplains.

I look at that picture of Vegas and I wonder if all those houses will be abandoned when electricity is so expensive that they can't air condition. Or when they can't get water. I wish they hadn't been built in the first place. They make a desert look ugly.

5:52 PM  
Anonymous Anonymous said...

They were going to build somewhere, where would a better place have been? In a forest? A prairie?

Anyway, the pictures of Vegas were pretty, such a nice grid, all compact. And, there's still plenty of desert with no houses on for you to see.

Of course, desert is some of the most boring land you can explore. You have to carry too much water to get very far, and the temperatures swing too wildly.

Justin

6:04 PM  
Anonymous kablamo said...

i'd like to see one of those 'sphincter constriction meters'. ...wonder how that works exactly...

6:50 PM  
Anonymous Anonymous said...

Wow, I go away for a couple of hours and there's lots more water porn!

Justin, yeah smart people would grab their water at the hotel first, but a bunch of us were escaping from our family reunion in a rental van. Upon hitting the edge of Vegas with a mess of cousins I looked around outside the van, looked around inside the van and pulled off at the first available spot - better a little smart just in time than not at all.

Megan, better we get smart about water later than not at all. Here in charming South Florida (where all things tacky and crooked end up) I see signs of of progress. Newer developments have mandatory preservation offsets (means I have fox, otters, deer, boar, armadillos, cranes, herons and alligators in the hood) Newer construction is remarkably tough - my house went through three signicant hurricanes in the last 3 years - including a solid 12 hrs of 110mph+ wind(sustained - not gusts) and had $39 in damages.

On the other hand we're not so many miles from the decaying Herbert Hoover Dike (there's an image!)and the "R-me kore of Injun-ears" won't release flood projections for when the levy breaks - citing N'nl security. 'Sposing Al Q wants to blow a hole in Lake O.

That would be the large blue spot on satellite views of Florida for those of you from lands far away. It's only about 10' deep right now, but is about 730 sq miles.

Floodplain? We consider 12' above sea level "Higher Ground". Highest spot in Palm Beach County would be our landfill!

-=richard=-

7:08 PM  
Anonymous Anonymous said...

Meggie!!!!! Your math is wrong!!!!

You wrote:

Waterstored = Waterin - Water out

That is not right. The correct equation is that the CHANGE in water stored is equal to water in less water out. What you wrote incorrectly has a stock on one side of the equals sign and two flows on the other side of the equals sign. That ain't right!

--Your secret Mr. S.

9:54 PM  
Blogger Megan said...

Hey Mr. S.

Went over and checked - you're the S I thought you might be. Teddy is around here sometimes; you can say hi to him too.

You're right; my equation's wrong, which is silly because it is so simple. I don't really want to change the left to be the change in water. Should I multiply the right by a time? I sorta meant for any year...

10:09 PM  
Blogger Marcus said...

I thought Lake Powell made you cry. It made Edward Abbey cry. The equivalent of the Grand Canyon is under there.

Seeing planes flying low over the Sierras made me cry. I know one of those damn things will wake me up at 2 AM sometime this fall, when I'm camping on a beautiful moonlit night, with a sound like a semi truck crossing an overpass right over your head. There need to be designated flying corridors over all major wilderness areas, not just the Grand Canyon.

Yes, I know full well I'm a nut on the subject, but it's TRUE. Silence is part of wilderness.

11:45 PM  
Anonymous Mitch said...

canals move water through space; dams move water through time

Ah, so all we need is a dam that can bring water back from the future!

Do not forget to hook your fingers through your beltloops.

Enough with the naughty imagery, already. I don't quite get the import of "beltloops" plural, though.


As far as cheap water goes, any thoughts on ag vs. urban water prices?

2:09 AM  
Anonymous Anonymous said...

I thought you were ridiculous saying that it was dirty talk, until I read:

"Most years, there will be no new wet water, because all the flows that are available in an average year are currently put to use. (And if you think that in-stream water use has been shafted for the past half-century, which is not a far-fetched thing to think, those rivers are oversubscribed.)"

And realized I was, indeed, putty in your hands. Please, Megan, this is a family blog!

5:51 AM  
Anonymous Peter said...

Is it true that so much water is taken from the Colorado River that it no longer reaches the Gulf of California in most years?

As for the wild development of Las Vegas, it may not be a particularly good idea from a resources point of view but you can hardly blame the people moving to the area. People who move in search of inexpensive housing and ample jobs are acting quite reasonably in putting their own interests first. Externalities such as water shortages should be deal with on the macro level.

But then, I'm biased. As a Connecticut resident in the early 1990's I (barely) survived the Great Recession that almost destroyed the regional economy. For a period of years the sight of a house or other building under construction was all but nonexistent. So it's very hard for me to get concerned about overdevelopment. The alternative's a million times worse.

7:44 AM  
Anonymous Anonymous said...

Meggie,

That is a very clever idea, multiplying by time on the right hand side of the equation---in essence integrating over the flows to get a stock. But you would still be missing the initial stock.

That is, if the total water behind the dam at time t is denoted Wt, and the initial water at time t = 0 is denoted by Wo, then Wt would be defined by,

Wt = Wo + Integral(flows in - flows out)dt,

where the integral is take from time t = 0 to time t = t. That is, to be accurate, integrating over time on the right hand side is not enough. One must still account for the initial amount of water behind the dam, Wo.

But please understand that as I tell this to you, I am standing up, leaning back, and hooking my fingers through my beltloops.

--Your Secret Mr. S whose IP address you stalked.

6:49 PM  
Anonymous Francis said...

Peter: yes. The marshes at the mouth of the Colorado River are vanishing at a frightening pace.

engineering note -- the Colorado River runs virtually dry just before the border with Mexico, at the Imperial Dam. California diverts Mexico's allocation out of the river in order to take advantage of a quirk in geography that allows for the use of that water to make hydroelectric power.

the impact of this diversion on species that historically were reliant on the lower Colorado river can be imagined, or read about in the Habitat Conservation Plan for Lower Colorado River species.

megan, SB 221/610, along with the Greenhouse Gases Bill, will radically change the pace of new development in California. Any time you want a CEQA/Water Code discussion, I'd be glad to participate.

4:08 PM  

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