Sunday, March 18, 2012

On dams and rivers, California's climate, and morals to stories

© 2012 Joshua Stark

Here in Northern California we are experiencing Winter in a Fortnight.  Of course, we are two months past the waterfowl hunting seasons, and so the storm doors are opened wide; the wind is howling, the hail may be here shortly, and the rain pours and pours.  California's is often called a "Mediterranean Climate", and I don't know if that is an accurate comparison for some parts of it, having never been to Europe, but I know it is inaccurate to label all of California with one climate  (for a great map example of what I mean, click here). Here in Northern California, for example, we get about 20" of precipitation in the Northern Central Valley, about 35"-40" in the foothills, and about 50"-70" in Blue Canyon (about twice the annual rainfall of Seattle).  The most important thing to know about our precip., however, is that it all falls between November and April-May.  Effectively, then, we are a schizophrenic climate: desert for half the year, and pretty wet the other half.  Our Great Wall, the Sierra Nevada, does a wonderful job wringing out rain and snow from the Pacific Ocean, giving us an amazing, fertile valley for much of the year and very deep snow drifts during the winters and springtimes (the entrance to Lassen Volcanic National Park usually has ten feet of snow by the end of the season).

Of course, being a Civilised Nation, we've plumbed the hell out of the whole river system, and now support one of the largest urban centers on Earth with water from 400 miles away.  We've also dammed nearly every river flowing out of the Sierra Nevada, doing great damage to one of the largest Chinook salmon runs in the world.  Both of these are issues I feel strongly about, but I won't go into them here.

Like every boy, I've always been fascinated by good engineering.  The juggling act that our dam managers have to conduct, keeping the balls of water storage, flood protection, and electricity generation in the air, is amazing.  They pore over weather predictions, flow charts, market prices and myriad other factors in determining just how much water to keep:  If you let too much go, there may not be another storm; but if you hold onto too much, you just might find yourself having to flood downstream communities.  Obviously, timely information and working equipment are vital, as is having boots on the ground, as it were.

When the weather gets this crazy, I often think of a story that may have happened when I was a boy.  In the early 1980's, a great hydrological engineer by the name of Nathaniel Hastings worked on-site at a dam in the foothills.  It was a sizeable dam, and protected a few towns directly downstream.  Nathaniel was very good at his job, knew the weather like nobody else, and knew when and just how much to open those flood gates.  Of course, in California's zeal for the Next Big Thing, he (and a number of other engineers at dams up and down the Valley) was replaced by a system of mechanical equipment, cables and such, that were operated centrally from the power company's headquarters.  In Mr. Hastings' case, literally, there was a gigantic cable-operated lever (for you Brits, that's pronounced lehvr, not leevr) installed right where he used to sit at the controls.

Well wouldn't you know it, the on-and-off nature of California's climates being what it is, a huge cold front froze up the mechanical equipment, and with the roads out (why plow when nobody is going to be there?), the next rainfall blew out the gates, and flooded three towns and hundreds of thousands of farm acres.

It was then that California learned its lesson:  better Nate than lever.


Hippo said...

Man this post of your is so close to my heart.

As you know, I was inundated by the sea and lost quite a bit when the sand bar protecting the entrance to the river mouth was washed away. This, apparently, wass as a result of the river being damned up stream reducing significantly its flow and the amount of silt it carried. With no replenishment of the sand bar, it was quickly overwhelmed and now the coats is being reoded.

Josh said...

I know too much about the impacts of dams. California's Sierra Nevada rivers were all dammed at their "fall" line, before we really knew what that meant. Salmon used to run in the millions through our rivers, hundreds of miles and thousands of feet into the mountains. Though we've got a decent run now (about 700,000 fish, due to hatcheries), our last crash (2007-08) had runs of fewer than 10% of a typical run. We almost lost them forever.

My Delta's ecosystem was altered completely by the loss of that silt you mention, plus additional bad silt earlier (from the gold rush era) that carries tremendous amounts of mercury. Now it is not recommended for people to eat more than one serving of Delta fish per month.

I've also seen the impacts on silt and beach movement from the addition or removal of jetties. In fact, since your beach is suffering from less silt, perhaps you should consider building a jetty. I hate engineering solutions to such issues, because it always has unintended consequences; in your case, however, you might want to consider the impact on your 'good' neighbor... is he downstream of the littoral current? If so, you could capture sand that would be heading to his beach, extend the river mouth, and maybe even add some more useable land to your own property. I'm no engineer, though.