Smithsonian.com

Since its construction in 1964, the Glen Canyon Dam in Northern Arizona has depleted the sandy sidebars of the massive Colorado to just one quarter of their original size, leaving archaeological sites vulnerable to wind and destroying the natural habitat of dozens of fish species.

To try to remedy this, last Tuesday, authorities flooded part of the Colorado. The man-made flood—using 300,000 gallons of water per second for about 60 hours—was the third in the Grand Canyon in the past 12 years. The previous two weren’t entirely successful, as The Economist points out:

Floods were sent down the Grand Canyon in 1996 and 2004 and the results were mixed. In 1996 the flood was allowed to go on too long. To start with, all seemed well. The floodwaters built up sandbanks and infused the river with sediment. Eventually, however, the continued flow washed most of the sediment out of the canyon. This problem was avoided in 2004, but unfortunately, on that occasion, the volume of sand available behind the dam was too low to rebuild the sandbanks.

This time there is enough sand behind the dam. And most environmental groups argue that these kinds of floods need to happen more often to ensure that sediment levels remain steady. But there’s an economic downside to the floods: the water used in the flooding will not go through the hydropower turbines in the upper river, costing those power producers about $1 million.

In a month, scientists will be using sonar and surveying tools in the river banks to figure out how well the flood worked. With better models of sandbar formation, they’ll be better equipped to decide whether more frequent flooding is worth the high price tag.

(Flickr, via jackfrench)

Politicians, journalists, even scientists love to talk about the “promise of biofuels.” But a thorough news feature in last week’s Nature reveals just how empty that promise may be.

Shown above is a Midwestern plant in which corn starch is turned into ethanol. Global ethanol production hit 13.2 billion gallons in 2007, more than double the production four years before. In the U.S., almost a quarter of all corn production now goes toward making ethanol. But, as Jeff Tollefson points out in the Nature piece, the agricultural techniques used for ethanol’s production “often damage the environment on a scale that far outweighs any good achieved through the biofuels’ use.”

Enter “second-generation” biofuels made from trees and grasses, which are cheaper and most sustainable raw materials than corn. A big push in the industry right now, according to Tollefson, is turning cellulose (from the cell walls of plants) into fuel. But there’s a big catch to that approach, too:

The fly in this ointment is that the world cannot yet boast a single commercial-scale cellulosic-ethanol facility. Breaking cellulose down into sugars is not easy work, and can use up a lot of energy; what’s more, not all the sugars produced are easily fermented.

Even if bioengineers successfully tinkered with those chemical processes, and even if they created a crop that could be an ample source of the cellulose, they’d still need to figure out how it could could all be done on a large scale. With all of the roadblocks, Tollefson argues that biofuels “will never take over the whole liquid-fuel market, let alone amount to a large proportion of total energy use.”

The best option, he concludes, would be to increase our fuel efficiency:

In the same law that expanded the ethanol mandate, Congress also increased the fuel-efficiency requirements for vehicles by 40%…And as Ingram points out, “If we increase gas mileage by 1 mile per gallon, that is about equal to all the ethanol we are making right now from corn.â€?

(Flickr, by fredthompson)

A couple of weeks ago, I wrote about the eco-friendly Masdar City, in the Persian Gulf, which will run largely on solar power. When he wrote about the city, NYT columnist Andrew Revkin lamented that such a thing wasn’t happening in the Southwestern U.S. But maybe California is headed that way.

In the last six years, the amount of photovoltaic-produced power used by Californians has grown by 17 times, according to the California Energy Commission. At the same time, the average photovoltaic system size has decreased, indicating more and more cases of residential (versus large commercial) use.

The clever folks at Cooler Planet found an interesting way to play with the data:

Rather than reading over data and spreadsheets, we thought it would be interesting to create an interactive heat map that depicts the concentration of solar installations (number of systems, total watts, average system size, and carbon emissions) in California and the progress solar has made over the last decade.

Above is a screenshot of their map, showing (in teal) all of the solar installations in California since 2002.

(Image: NASA/California Energy Commission; Hat Tip: Green Gabbro)

Whether or not geology’s Powers That Be accept “The Anthropocene� as an official epoch (see the January 31 entry in The Gist), we humans are leaving quite a mark on the geologic record. Pardon the shameless shilling for my colleagues at Smithsonian.com, but some of the stories in their new “Ecocenter: The Land� package illustrate why The Anthropocene is a useful concept. From agriculture to deforestation to sprawl, we’re changing the planet arguably as much as any errant asteroid ever did.

(The Anthropocene sounds fairly nonjudgmental, doesn’t it? Until now, my favorite name for these modern times came from a cartoon. It shows a couple of guys in space suits digging up a ruined building with a sign on top that says “Tanning Salon.� The caption? “Future archaeologists unearth yet another relic from the Age of Vanity.�)

It’s hard to get one’s head around how human activities add up on a global scale. Did you know that we move many times more dirt than all natural processes combined? Wind and water erosion, landslides, sand storms—you name it, bulldozers beat it.

What surprised me recently was just how long humans have been moving mountains. Or valleys, in this case. Researchers from Franklin and Marshall College in Pennsylvania figured out that the streams we Easterners love to fish and canoe in and hike along look nothing like their natural state. Today streams have steep banks and gravel riffles and defined channels. But 500 years ago they would have been wide, shallow and marshy.

What reconfigured the entire Eastern Seaboard’s waterworks? Mills. Robert Walter and Dorothy Merritts looked at old photos, property deeds, censuses and other historic records and found that Eastern rivers had mill dams blocking their flow every few miles, most built between 1600 and the early 1900s. The mills ground grain, sawed lumber, ran iron forges. Mill owners built dams that pooled water behind the mill and kept the mill wheels turning reliably. When coal and oil made mills obsolete, they broke down, washed away, and people pretty much forgot about them.

The study seems to answer a longstanding question in geology: where did all the sediment go? Scientists knew that logging and poor agricultural practices caused massive erosion, but it didn’t end up in the oceans. Now we know, thanks to Walter and Merritts’ analysis of satellite images and stream beds: the sediments were backed up behind thousands and thousands of dams. When streams finally breached abandoned dams, they cut through meters-deep sediment and carved the steep channels we see today.

It’s a surprising finding, yet one that makes perfect sense if you look at place names (my street, miles from any modern stream, has the name “Mill� in it) or notice all the crumbling stone mills when you hike around in second-growth forests. Now the question is what to do with the information: should stream restoration projects aim to recreate 16th-century swamps? (How to rebuild streams is contentious enough already, as I learned from “Fish Story� in the August issue of Smithsonian magazine.) If so, will that decrease our risk of catastrophic flooding?

The research was done on the East Coast, but the lessons apply elsewhere: rivers in the Pacific Northwest were once frequently blocked by treefalls; now they also run faster and deeper than before. And Europe? They’ve been damming their rivers for about a millennium.

Do you have a favorite example of why we should—or shouldn’t—call the modern era The Anthropocene? Post your thoughts here.

Laura Helmuth is a senior editor at Smithsonian magazine.

In a region prone to earthquakes, a little warning could make a big difference. Though current early warning systems—such as those in Japan, Mexico and Taiwan—can only give a few to tens of seconds warning before the ground starts to shake, this is enough time to allow some short-term mitigation. Trains and elevators can be slowed or stopped, utilities and factories can put into safe modes, and people indoors and out can move to safer areas. Damage will still occur, but it could be lessened.

Japan is particularly earthquake prone (above, Tokyo devastated after a 1923 earthquake), so it’s no surprise that the country would develop an earthquake early warning system. After years of development, it went online in October. However, the success of the system has been called into question. On January 26, a magnitude 4.8 earthquake shook the Noto Peninsula in the Ishikawa Prefecture about 200 miles northwest of Tokyo. No warning had been issued for the quake, and the Japanese media claimed that system had failed. But did it?

The Japanese system is designed to issue a warning only if the predicted intensity of the earthquake will reach lower 5 or above. (Intensity—see here for an explanation of the Japanese scale—is a measure of the strength of seismic motion at the surface, whereas magnitude is a measure of the energy released at the source of an earthquake.) An earthquake with an intensity of 4 will shake books off the shelf; in a lower 5, the bookshelf will fall over. For the January 26 earthquake, the system predicted an intensity of 4, but in one town, Wajimamonzen, the intensity reached lower 5. Government officials from the Ishikawa Prefecture, though, received no reports of injuries or damage from the earthquake. And a representative of the Japan Meteorological Agency told the journal Nature that this kind of variation was within expected limits.

It can be argued that, technically, the system did fail and there should have been a warning. With a system still in its first year of operation, it is no surprise that it still needs perfecting. However, if there was no serious damage from the earthquake, and the system is meant to mitigate damage, doesn’t this also call into question where they have placed the cutoff? If warnings are given too often for quakes that don’t do much damage, is there a danger people would grow complacent and begin to ignore them? And then what would happen when Japan’s equivalent of the “big one� (see Tokyo Tremors in Earthquake!) occurs?

(Image: USGS Photographic Library, George A. Lang Collection)