Down to Earth

New blog: Cr!key Creek

2009-03-04T02:45:00.002-06:00

Daniel Collins is now blogging at Cr!key Creek.

The sun sets on Down to Earth

2006-12-11T23:22:00.000-06:00

I started Down to Earth back in May 2006 hoping I could improve environmental literacy. I think I achieved that goal. For example, one frequent commenter on similar blogs cited my post about media coverage of the potential climate change-hurricane link. However, based on all the scant evidence I have accrued thus far, the benefits of my blogging have been outweighed by the costs.

Blogging is a huge commitment. I have to think of what to write, write it, attend to email, monitor visits to the blog, follow other blogging activity, and maintain a presence in the blogging community. Even the bare bones blogging takes a lot of effort, and it doesn’t come naturally to me (I prefer other forms of educational outreach). Maybe things would be better if somehow Down to Earth became a hit, but it hasn’t.

While I have an important and uncommon blogging beat (water), I think I will serve humanity all the more for stopping blogging. Time would be better spent at this stage using my expertise and energy to solve problems directly on the ground, or to create new knowledge necessary to do so. What roles do different ecosystems and land uses play in providing ample and usable water? How do land use changes affect eutrophication? Can this knowledge be used to help developed nations control water quality problems, and allow developing nations to leapfrog our mistakes? And so on. It’s a long list – at the interface of ecology and hydrology.

All the resources that I’ve built up will remain. Some posts, in my opinion, are top notch – at least for freely available information. Here are my favourites:

Hydraulic redistribution
The curse of the One Rabbit: Tree rings corroborate Aztec folklore
Drought and pinyon pine populations
Insufficient water to meet needs
Reporting on hurricane-climate change connections
Protecting Oman's water resources heritage
Reading weeds
Afforestation erodes Japanese chopsticks

The comments will remain active for a short while, but in time commenting will be disabled, and my email will be removed. It probably won’t be too hard to track me down if so desired.

I may resume blogging in the future, if the conditions are right. I have learned many things while blogging these past months, and one of them is that blogging can be a potent scientific and educational tool. But it is now time to learn other things, and to solve other problems. Down to Earth has run its course, and so I leave you with one last stanza.

From cool springs seeping
To creeping golden shores
Does the river run.

Owens Valley gets it water back

2006-12-10T12:52:00.000-06:00

Nearly a century ago, William Mulholland, then Los Angeles's water engineer, diverted water from Owens Valley to L.A., leaving a lot of people very angry. Roman Polanski turned the saga into a 1974 film, Chinatown, starring Jack Nicholson, Faye Dunaway, and John Huston, which I highly recommend. A 1986 book by Marc Reisner, Cadillac Desert, covers land development and water resources in the U.S. West more broadly - also a good read.

But now, L.A. is returning Owens Valley's water. Listen and read the NPR coverage, then go rent Chinatown.

Carbon-negative biofuels

2006-12-10T12:34:00.000-06:00

The graphic of this week's Science comes from a report by David Tilman, Jason Hill, and Clarence Lehman at the University of Minnesota entitled Carbon-Negative Biofuels from Low-Input High-Diversity Grassland Biomass. NPR covers the research with both text and audio.

"Biofuels derived from low-input high-diversity (LIHD) mixtures of native grassland perennials can provide more usable energy, greater greenhouse gas reductions, and less agrichemical pollution per hectare than can corn grain ethanol or soybean biodiesel. ... LIHD biofuels are carbon negative because net ecosystem carbon dioxide sequestration ... exceeds fossil carbon dioxide release during biofuel production ... . Moreover, LIHD biofuels can be produced on agriculturally degraded lands and thus need to neither displace food production nor cause loss of biodiversity via habitat destruction."

Philosophia Naturalis #4

2006-12-07T14:07:00.000-06:00

Welcome to Philosophia Naturalis #4, a compilation of outstanding blogging on physical sciences and technology over the last month. Check out the carnival homepage to learn more and submit to up-coming carnivals, so you, too, can experience the centripetal acceleration, er... , be part of the physical revolution.

Here’s what we’ve got for you today...

Tech-Heavy Science

Chris Rowan, of Highly Allochthonous (and the next host of Philosophia Naturalis), highlights the use of nukes to study seismology.

At Geek Counterpoint we read about engineering design and failure rates in the context of NASA missions.

And if you approach Clifford Johnson, at Asymptotia, he’ll tell you about the International Thermonuclear Experimental Reactor (ITER), which has high hopes of energy in the future.

Cosmoslogy

Charles Daney at Science and Reason (and the brain behind Philosophia Naturalis) removes a small thorn in the side of Big Bang Theory.

At Cosmic Variance, Sean Carroll explains how the recent discovery of 21 super-novae has helped understanding dark energy.

Meanwhile, Phil Plait, the host of the Bad Astronomy Blog (nominee of a science blog award), writes about NGC 1316, an elliptical galaxy on a collision course with…, well, read it.

Across Disciplines

Moving from big to small, Chad Orzel at Uncertain Principles highlights the incorporation of General Relativity into the study of protein folding.

And at Shtetl-Optimized, Scott Aaronson recalls what the major contributions of theoretical computer science in the last 30 years have been.

The Human Element

Moving to a lighter note, but one no less important, relax in the Lounge of the Lab Lemming with a phase diagram of pie crust pastry.

Last, but certainly not least, Sabine Hossenfelder at Backreaction discusses why we find images aesthetically pleasing.

But Wait, There’s More!

For the next edition of Philosophia Naturalis, and to submit and suggest posts of your own, pay a visit to Chris Rowan at Highly Allochthonous.

The Tangled Bank Survey #68: The Voyage of Discovery

2006-12-06T12:04:00.001-06:00

In the spirit of the original Tangled Bank Survey, here is a review of the most recent science blogging.

1831 December 27- Navigating Scientific Uncertainty

We left Plymouth harbour this morning. As ship commander I made sure we had the most advanced nautical devices to date, to navigate uncertain seas. No messing about with Greek calculators [Salto Sobrius] for us. It was also crucial to understand the uncertainties of the weather [Backseat Driving], as well as risks to our personal health while at sea (to this end I commanded every sailor to have a talk with a health insurance specialist [RDoctor Medical Portal] prior to departure.)

1832 February 28 - South American Beauties

The assortment of life Darwin discovered upon reaching South America was dazzling: a false crocus geometer, a yellow-spotted salamander, a pallid bat, and a tiger moth [Living the Scientific Life]. They certainly inspired the imagination about how life forms, or biomorphs [Science Notes], come about.

1834 June 10 - A Closer Look

Today we passed through the Magdalen Channel into the Pacific Ocean. Darwin has been busy with his microscope, examining hard boiled eggs preserved in volcanic ash [Living the Scientific Life], and crawling cells [The Daily Transcript].

Mr. Darwin imagined a time when he could see the very structure of life itself, which is most assuredly complex [Genetics and Health], but which could offer a great depiction of the branching of life forms [Living the Scientific Life]. He hoped also to see how the action of Really Neat Advanced ideas (RNAi) could benefit human health []Living the Scientific Life], or to see how proteins are synthesised [BoingBoing].

1835 September 15 - To Live Forever or Die Trying

Once at the Galapagos archipelago, Mr Darwin collected a number of specimens. The tortoise he collected seemed of such age, that it prompted much contemplation of strivings to remain alive for a good many years. I could certainly do with finding the Fountain of Youth. I’m not getting any younger, you know.

Thoughts on the matter included cellular senescence [Ouroboros], supplemental melatonin [Ouroboros], and even engineering analysis [Fight Aging]. After a chat about life-extension in general [Pimm – Partial Immortalization] with one of the crewmen taking a leave from Cambridge University, it was refreshing to realise differences in opinion among researchers in the field have been progressively eliminated over time [Fight Aging].

An alternative approach to immortality would be to ask an esteemed novelist to immortalise oneself in a book or play - there are certainly too few scientists as characters in entertainment these days [Eastern Blot]. However, it is heartening to know of scientists, one phychologist in particular, who offer advice to playwrites [RDoctor Medical Portal].

1835 December 21 - Greener Pastures

H.M.S. Tangled Bank arrived at New Zealand, and anchored at a place called the Bay of Islands. The bright red flowers of the pohutukawa [Down to Earth] tree were a delight. The landscape has a very English feel to it, a fine opportunity for grazing cattle and sheep. I imagine the ingenious locals, with the no. 8 wire, could even develop some way of tapping the energy of cow manure [Science Sketches].

1836 January 12 - Australian Dreamtime

We anchored at Sydney Cove, and went to shore for a fine turkey meal. After dinner we wandered Sydney’s alleys, discussing how hunting or changing habitat have affected turkey population dynamics [Thoughts From Kansas].

That night, we all slept well. I think it had something to do with the turkey. I learned later Darwin dreamed that his ideas about the diversity of life were proven wrong by a rabbit [Talking Squid]. I assured him it was merely a dream, or that he was in some sort of trance where people’s brains operate differently [Scientia Natura]. I suggested he try some mental exercises [SharpBrains] to recover his intellectual prowess.

1836 May 31 - Stowaways Discovered

Upon arrival at the Southern tip of Africa we noticed a great scurrying of rats off the ship. We wondered if they smelt some more appetising food ashore. They certainly have powerful senses of smell, so powerful, we thought, that the rats could be used to detect explosives in fields [Walking the Berkshires].

And while wandering around Cape Town, Mr. Darwin noticed a group of people arguing over some trees [Invasive Species Weblog]. Some people wanted the trees to stay, others wanted them gone. It seemed to Darwin that such an argument, if not based on facts, would just alienate people from one another.

1836 August 21 - Are We There Yet?

The seas were rough these past few days as we crossed the equator. The vigourous rocking back and forth made poor Mr. Darwin ill. During a serious bout of sickness he joked he would have to adapt to these cyclic environmental stimuli [A Blog Around the Clock] or perish. Later that night I heard him repeatedly chanting “om” to calm his nerves. Or was it “ome”? [A Blog Around the Clock]

When both seas and stomachs became calm again, there was a general thirst for land once more - to have a pint of beer and see friendly, pretty faces [The Skwib]. This aroused my attention, but I’m told women are aroused just as quickly [Science and Reason], nudge nudge, wink wink, know what I mean, know what I mean, say no more, say no more! A nod's as good as a wink to a blind bat!

Mr. Darwin, meanwhile, was contemplating his next challenge: how to explain his new theory of life’s diversity in the classroom [The Voltage Gate].

1836 October 2 - Epilogue

Today we reached our final destination. With the 68th voyage of the H.M.S. Tangled Bank now complete, be sure to board the ship again in a fortnight, with Captain Martin Rundkvist of Salto Sobrius at the helm. Submit proposals for scientific studies via The Tangled Bank shipyards.

Pohutukawa

2006-12-06T09:41:00.000-06:00

Pohutukawa or New Zealand Christmas Tree (Metrosideros excelsa). Pohutukawa is the more common name (which is pretty typical for NZ plants and animals), a Maori word for "drenched in mist." The trees are native to coastal regions of the North Island, New Zealand, producing iconic red flowers at the end of December. They are a favourite food of the common bushtail possum – perhaps NZ’s most despised pest. In the tree’s shade are another iconic image of NZ – sheep. Photo © 2006 Daniel Collins.

Sherwood Boehlert's advice to scientists

2006-12-05T12:49:00.000-06:00

Science has an interview with Rep. Sherwood Boehlert (R-NY), the outgoing chair of the house Science Committee (retiring from the House after 24 years) and self-proclaimed "cheerleader of science." I have great respect for this guy, and I know many others do too. He became firmly ensconced on my radar when he called Joe Barton's (R-TX) probe of climate change science's "hockey stick" a "misguided and illegitimate investigation."

In the interview, Boehlert offers advice to scientists hoping to get their messages
across:

"you have to prove to me that it has some public benefit besides a bunch of Ph.D.s sitting in a laboratory coming up with something that they can publish that no one can understand."

He wants scientists to do more advocacy, but not where they fundraise for candidates. He’d rather scientists invite their local representatives to their universities to discuss the science and it implications, in an accessible way.

"Why aren’t they visiting candidates and explaining to them, on their home turf at the university in their district, why they should be really interested in their agenda? I tell scientists that their new best friends should be these new congressmen. Don’t just visit them in Washington with a lobbyist. Invite them to come to the university in their district, not to a technical presentation that they probably can’t understand, but to a general discussion of what’s going on and what it means. … I think that the scientific community will be an abject failure if, when these new freshmen start campaigning for reelection, at least a few of them don’t have a science component in their platform."

Nobelity

2006-12-05T12:01:00.000-06:00

Science recently reviewed an independent film by actor and filmmaker Turk Pipkin, entitled Nobelity. The film follows nine recent Nobel laureates discussing what they consider the major problems facing humanity as well as possible solutions.

Wangari Maathai (Peace, 2004): persistence, deforestation, and erosion.
Joseph Rotblat (Peace, 1995): clean water.
Amartya Sen (Economics, 1998): hunger, over population, and experiential education.
Richard Smalley (Chemistry, 1996): nuclear disarmament.
Desmond Tutu (Peace, 1984): "The sea is actually made up of drops of water. What you do, where you are, is of significance."
Harold Varmus (Medicine, 1989): disease and health disparities.
Steven Weinberg (Physics, 1979): climate change and global warming - "the burden of proof should be not to prove that it is happening but that it isn't."
Jody Williams (Peace, 1997): land mines.
Ahmed Zewail (Chemistry, 1999): education to build understanding between cultures.

(NB. I wonder if Science got the themes of Rotblat and Smalley round the wrong way.)

The reviewer writes, “the sincerity of the Nobel laureates makes this film a uniquely intimate though sobering effort by these individuals to express themselves outside of research labs or scientific journals.” Proceeds will go to projects working on solutions to humanity’s problems.

Ecological Society of America blog

2006-12-05T11:17:00.000-06:00

The Ecological Society of America (ESA) has started a blog: ESA News and Views (plus a new web interface to boot, which looks inspired by standard blog formats). Is this the first professional academic society to start a blog? I don’t know, but I’m sure it will be a model of such ventures. ESA is pretty innovative when it comes to increasing the circulation of knowledge. The blog coordinators invite contributions to supplement their own posts. A recent post wonders how blogging will improve academic publication.

EPA libraries closing

2006-12-05T11:13:00.000-06:00

I recently learned some oldish news that EPA libraries are being closed, or their hours reduced, as a cost-cutting measure. Five libraries have already been closed to date, their resources being digitized, dispersed, or disposed of. Unions representing EPA employees have complained that the closings would hamper their work. Senators have questioned the funding cut that prompted the closings, claiming that the libraries more than pay for themselves. House Dems have asked the GAO to examine the library closure plan. And the Union of Concerned Scientists is encouraging action, with more information than you’ll find in any news piece.

Exodus from a floodplain

2006-11-12T21:19:00.000-06:00

Hamilton is on the move. A town of roughly 300 people, 80 miles northeast of Seattle, WA, is drawing up plans to move a mile north to escape repeated flooding by the adjacent Skagit River.

The New York Times’s William Yardley describes the situation in the wake of yet more flooding (“After More Than a Century of Soaking, Washington Town Mulls Move to Higher Ground”).

The long history of flooding along the Skagit Valley has instilled residents of Hamilton with a very religious response to such “acts of God.” They roll up their rugs, empty their kitchen cabinets, move good furniture to the second floor, and ascend to higher ground and the shelter of the church on the other side of the highway. Damage over the years has exceeded $10 million.

Now there’s a plan to shift Hamilton’s residents to the other side of the highway on a permanent basis, out of harm’s way. The major hurdle is that people don’t have the money to move. A recent downturn in the local timber industry has led to economic hardship for many residents. A large proportion of Hamilton’s households have been classified as low- to moderate-income (their total income is 80% or less of the median Skagit County income). This has made the low-cost housing in the floodplain particularly attractive.

To solve the financial hurdle, the Hamilton Public Development Authority was created. No one would be forced to relocate, but the development authority would shoulder much of the financial burden of moving the 400 residential homes. An estimated $4 million lies in buying up the new land alone.

Supporters of the move say it would improve the residents’ quality of life, as well as improve habitat for bald eagles and six species of salmon. With warnings of contaminated groundwater following these floods, I expect the move would benefit downstream communities too.

To paint a fuller picture of the town and its woes here are some doctored images from Google Earth and the Washington Military Department Emergency Management Division. The presence of old meander bends is evidence of the valley’s on-going flooding. I’ve highlighted one to help you orient the lower aerial photo. I've also marked what I'm guessing is the boundary of the floodplain, outside of which flood risk is largely eliminated.

Before last week, the last major flood in the valley occured in 2003. Courtesy of the USGS, here's a record of the height of the Skagit River at Concrete, upstream from Hamilton. It looks like the 2003 flood was worse than last week's, but not by much.

I would be keen to know whether forestry operations in the Skagit's catchment have affected flood occurrence in any way. But this wouldn't be as important as the basic question of where to situate your community. If the economics agrees, moving to higher ground looks to be a smart move. I know Stevie agrees.

Calls for Philosophia Naturalis #4

2006-11-07T14:25:00.000-06:00

Philosophia Naturalis is a blog carnival for the physical sciences and technology, providing a counterpoint for Tangled Bank which is a carnival with a biological emphasis. I will be hosting the fourth installment of Philosophia Naturalis on December 7. Please email any article suggestions to downtoearthblog * yahoo * com, and we can have a big old yarn come December.

Panta Rei (#4) comes Down to Earth

2006-10-28T15:45:00.000-05:00

Welcome to the fourth installment of Panta Rei, the blog carnival that's all about heat and fluid flow. The posts we have this round take us from outer space, down to earth, and inside our kitchen. They conclude with a simple participatory experiment, whose results you can leave in the comments.

In his series on space applications of heat transfer, Subrahmanya Katte provides Panta Rei two posts on protecting spacecraft from excess temperatures. In one, he explains why spacecraft re-entering Earth’s atmosphere do so not with a pointy, aerodynamic nose facing the Earth but with a flatter, bluff surface. This is so that the shock wave produced, which heats the air, is further away from the spacecraft itself. In the other post Katte explains why the space shuttle employs reusable tiles to protect it from the heat produced during re-entry, while spacecraft like the Apollo capsule can not.

Arunn Narasimhan, writing at TechBizMedia, proposes a scheme to increase the flow of money using a device that controls the flow of thermal energy. The composite heat sink he presents may be useful to cool on-board electronics in Indian space vehicles, among other things.

Arunn, this time writing at Nonoscience, traces the evolution of models of porous media flow from Henry Darcy, back in 1856, to the present day.

Looking a fluid flow inside porous media, like sand, is one thing. Adding macropores and plant roots is a whole new ball game. Yours Truly, here at Down to Earth, describes a phenomenon known as hydraulic lift, in which plant roots act as low-resistance tubes to allow soil water to move from wet to dry zones, without the need to move through the porous soil medium.

Alex Liberzon, of Alex’s Blog fame, uses particle image velocimetry (PIV) to illustrate the effect surfactants have on reducing drag. He also has a nice compilation of interesting flow patterns, that inspire poet and scientist alike.

The physics of fluid flow is most comprehensively embodied in the Navier-Stokes equations, but solving them can prove challenging. For anything but simple problems of fluid flow, there is no analytical solution available, and numerical solutions must be developed using computers. Working out how to solve the equations analytically, though, is a prized goal, so much so that the Clay Mathematics Institute has offered US$1 million to whoever sufficiently advances the ability to do so. About a month ago, a mathematician almost did, and blogs carried the story with gusto. Seed Magazine provides coverage of this coverage.

Gavin Schmidt, at RealClimate, draws upon an editorial by Carl Wunsch on the Gulf Stream – the oceanic current that moves northeast off the eastern coast of North America. He raises the issue because of confusion between the Gulf Stream and the Meridional Overturning Circulation (which is often conflated with the Thermohaline Circulation).

Javier Pazos, The Science Pundit, reports on a Nature article about volcanic eruptions. The focus is a curious series of events that lead to particularly explosive eruptions.

In a similar neck of the woods, an old post at Interesting Thing of the Day provides us with the basics of mantle convection.

Lastly, for the experimentalists among you lacking a personal volcano or tectonic plate, let me bring some research from Corgilabs out of the freezer. Eric brings us into his lab with a series of experiments on freezing coke in a sarcophagus. Experiments I, II, III, IV, IV-followup.

An easier kitchen-based experiment, relating to mantle convection, calls for a pot of water (copper-based pot is better), cooking oil, and a gas burner. Heat the water so convection starts, but not so much that the water starts to boil. Add oil at any time (don’t add so much as to cover even a quarter of the water surface), and watch how the convection moves the hydrophobic oil around the pot. I just tried the experiment with my electric element on my stove, but I can’t control the heat well enough – hence the gas burner. Does the oil aggregate? Do the size and number of oil aggregates fluctuate over time? How does water depth (and hence size of convective cells) affect oil dynamics? How does the temperature affect these dynamics? What happens when you add more oil? Leave results in the comments.

Heat and fluid flow blogging reminder

2006-10-25T14:46:00.000-05:00

If you have a blog post related to heat or fluid flow, or if you read one that you'd like to share, send me the link and I'll add it to this coming edition of the blog carnival Panta Rei on the 28th.

A remarkable moment in science journalism

2006-10-25T09:14:00.000-05:00

Andrew Dessler, climate scienist at TAMU, has shifting blogging to Grist. If I followed just one climate science blogger, he would be it. He makes the science accessible and illustrates the connections to policy. What's more, he does it in a hospitable way. Instead of a journalist covering what scientists say, we're skipping the middle man. This will remarkably improve the calibre of Grist and of environmental literacy, while putting Andrew's spam filter to the test.

Hydraulic redistribution: Mass transport by underground tubes

2006-10-24T00:07:00.000-05:00

Deep down, plants suck.

We should all have a good picture of how plants get water and why. Water is taken up by roots and is transported, along with nutrients, up into the plant through tubes called xylem. Essentially, once in the leaves, the H of the H₂O is stripped away, and combined with C and O from CO₂ to produce carbohydrates. The waste product, O₂, is spat out through openings called stomata (oxygen – "they call it pollution, we call it life").

It’s impossible to suck up water above 10 metres in height (at least on Earth). Plants must rely on capillary forces to entice water up the narrow xylem, driven by evaporation of water inside the leaves and its movement out through the stomata. But something else is going on inside the darkness of the earth, in the plant’s hidden half.

For plants that close their stomata at night there is no upward flux of moisture from the roots to the stems. But that doesn’t mean water stops flowing in the roots. On the contrary, plant physiologists are finding an increasing number of species that exhibit what is known as hydraulic redistribution.

Roots have developed components that greatly restrict the movement of water out into the soil, but the gates aren’t 100% effective, particularly among younger roots. If some roots are located in dry soil, and others in wet, the water in the roots’ xylem will be subjected to a pressure gradient. The drier soil will be using the xylem as a straw to suck moisture from the wetter soil. This is a purely hydraulic phenomenon, not biological. Water within the soil can thus be redistributed from wetter regions to drier, provided the pressure gradient is strong enough to overcome the resistance imposed by the xylem. This only occurs in times of water scarcity.

If deeper soil is wetter, as is more often the case where hydraulic redistribution has been observed, the roots passively lift water into shallower soil. More water thus becomes available to the abundant shallow roots, to be taken up for photosynthesis the following day. Because water that would have otherwise infiltrated deeper, beyond the reach of roots, is shuttled upwards, more water is available for transpiration. This increase is small but significant, for both plant productivity and the water cycle.

The shallower water also allows greater absorption of nutrients, which are more often concentrated near the soil surface. What’s more, water lifted by deep-rooted plants becomes available to shallow-rooted neighbours (an example of facilitation; though this positive effect may be outweighed by the negative of out-right competition).

Hydraulic redistribution is a fine example of the overlap between physical and biological phenomena. Plants respond, and have perhaps even adapted, to the flux of moisture from wetter soil to dry, and it is roots through which the water is sucked.

(See some graphics here. For some primary sources about hydraulic redistribution, see here, here, and here.)

Australia drought sparks suicides

2006-10-19T13:10:00.000-05:00

This, following the most severe drought in Australia for 100 years:

Depression, isolation, alcohol abuse, family breakdown and suicide rates in regional and farming communities are all exacerbated in time of drought.

Web feeds: Saving time on the web

2006-10-18T09:05:00.000-05:00

If you know all about feeds, like RSS, skip this post.

If you don’t, and would like to have an easy way of following updates to your favourite blog or news provider, read on.

One of the ways I stay connected with current events is through a "feed reader" or "news reader". This is a service that monitors the content of blogs and other media, and collects all the modifications on one website. When I want to know what’s going on, I just go to one website, and I save a lot of time.

To get this going you need a reader. I use Bloglines. When I want to add blogs to my reader I look on the blog site for a link to their feed. You can see Down to Earth’s in the sidebar on the left (there are two options to choose from; it doesn’t really matter which one). I click on the link, and it takes me to a specially formatted webpage containing just the posts. I then copy the URL over to the feed reader. Et voila!

I then just have a bookmark for Bloglines instead of all the other sites.

Try it out. If you want more details, see Wikipedia, or just ask me.

Responding to drought: Balancing supply and demand in the UK

2006-10-17T08:17:00.000-05:00

Drought is about supply of water not meeting demand. While measuring the severity of drought is one thing, reducing the severity is another. Increasing supply and reducing demand are both options, so that the two are balanced.

For a sample of strategies available to wealthier regions, see this BBC coverage of a report by a group of UK civil engineers. Across three different stakeholders, the list of strategies include:

recycle more sewerage effluent as drinking water (supply)
more reservoirs (supply)
more desalination plants (supply)
pipelines from wet regions to dry (supply)
repairing leaky pipes (supply)
increase in cost (demand)
hosepipe bans (demand)
improved efficiency, e.g. aerated shower heads (demand)

Blog carnivals: History and future

2006-10-15T21:05:00.000-05:00

History Carnival #41 is up at ClioWeb. Is it odd for a science and engineering blog to submit to a history carnival? Not really. Biophysical insight is quite capable of informing historical analysis, as evidenced with my previous post on the Aztec and tree rings.

Turning to the future, Down to Earth will be hosting Panta Rei on October 28. Please forward pieces on heat and fluid flow to downtoearthblog * yahoo * com, with Panta Rei in the subject line.

The curse of the One Rabbit: Tree rings corroborate Aztec folklore

2006-10-14T13:02:00.000-05:00

Historical records produced by the Aztecs were pictorial books painted on skins or paper made from bark. The documents included maps, tribute records, genealogies of ruling families, and alteptl annals that mainly recorded the history of individual alteptl (city-states). The annals focused on religious and political events but a variety of natural phenomena were also recorded, such as volcanic eruptions, earthquakes, solar eclipses, storms, and drought.

In the pictorial manuscripts, history is recorded as a continuum of year signs with associated events. Year signs are comprised of a number (1-13) and a day symbol (e.g. rabbit, deer, flint knife). The Aztec calendar is such that particular pairs of numbers and symbols repeat only every 52 years. One of these known as One Rabbit was strongly associated with the occurrence of catastrophic events such as famine.

While the Aztec were recording their history on tree bark, climatic history was also being recorded on tree rings. Many trees grow in annual spurts creating concentric tree rings. The more favourable the weather in a particular year, the thicker the ring. Precise dates can be ascribed to each ring, and thus also to extreme climatic events such as drought.

If we weave the two parallel histories together – the annals and the tree-rings – we can see how the two threads match up. We can see how drought sensed by growing trees translates to droughts recorded by the Aztec. A group of researchers from Mexico and the U.S. did just this (see their article in BAMS). Between 1332 to 1543, thirteen obvious droughts can be identified in the Aztec records. Nine of these had below-average tree growth, the other four were only slightly above the long-term average.

One of the severe droughts led up to the famine of One Rabbit (1454), one of the most widely recorded calamities in Aztec history. The Codex Chimalpopoca reads

"At this time the people were one-rabbited, ... And for three years there was hunger. The corn had stopped growing."

The Codex Telleriano-Remensis depicts images reminiscent of the Dust Bowl. One image has been described as follows:

"three plainly dressed ordinary folk, two males and one female, whose rotating forms and closed eyes depict the fatal effects of yet another disastrous storm. Pictorialized by swirling volutes of dots, the catastrophe this time appears to be caused by gusts of wind or dust."

The account for 1505 recorded in the Codex Telleriano-Remensis depicts scenes of famine, starvation, and death similar to those of 52 years earlier: a weeping fugure and mummy bundle; extreme suffering; famine.

Within Aztec cosmology, the year One Rabbit was strongly associated with catastrophic events such as famine. Tree-ring data suggest their fear was based on long experience. Thirteen of the fourteen One Rabbit years from 882-1558 are covered by available tree-ring data. Ten of these years were immediately preceded by below-normal tree growth, and presumably poor maize yields.

Studying the Aztec’s curse of the One Rabbit shows how multiple lines of evidence, from social accounts and biophysical reconstructions, can be combined to build a more thorough picture of historical events.

More on drought monitoring

2006-10-14T11:11:00.000-05:00

John Fleck has followed my post on defining drought with some more background on the indices used. Particularly interesting to me, since I didn't already know about it, is a drought monitoring project based at Princeton. Juxtapose this with the Dartmouth Flood Observatory.

Science blog carnivals

2006-10-13T08:10:00.000-05:00

Tangled Bank #64 and Philosophia Naturalis #2 are up. Considers these carnivals shotgun sequences of the rapidly evolving science blog genome. Tangled Bank has a biological bias, Philosophia Naturalis a physical.

Trends in 20th century drought over the U.S.

2006-10-12T00:47:00.000-05:00

In my previous post I illustrated how decadal climate variability over the last millennium affected populations of pinyon pine in the US south-west. I will now narrow the focus to the 20th century and ask whether droughts are better of worse. (See this earlier post on the intricacies of defining a drought and how to measure one.) For the answer I’ll turn to a study published in Geophysical Research Letters earlier this year by two researchers at the University of Washington.

The researchers used a hydrological model to simulate soil moisture conditions and runoff over the continental U.S. for the period 1925–2003. Good enough records of soil moisture just don't exist over U.S., not even today, so a model is used to reconstruct the record (recall that the best estimate of an agricultural drought is obtained through this type of numerical model, rather than an index based on the climate). They used the Variable Infiltration Capacity model, which calculates the energy and water balance at each point based on climatic inputs and a description of the land surface (soil, vegetation, topography). They examined agricultural and hydrological droughts, using estimates of soil moisture and runoff, spat out by the model, as drought indicators. They then used a statistical test (the Mann-Kendall test, if you really want to know) to see whether there were any trends in the model output. Indeed there were.

Over the 20th century, the soil became wetter over the majority of the country, while drying predominantly occurred in the Southwest. Trends in annual runoff were similar. Decreases in drought severity occurred in the Northeast, Great Lakes, Lower Mississippi, and the Pacific Northwest; increases in severity were located mostly in Texas, the Southwest and intermountain West. The eastern U.S. and Midwest saw a reduction in drought frequency, while the Southwest saw a little increase. Drought duration decreased in the Great Lakes, Mississippi basin, and Pacific Northwest, while duration increased in parts of the west including California and the interior.

While there has been a general increase in precipitation over the U.S., some areas still exhibited worse droughts. In those parts of the country that showed a decrease in soil moisture over the century (locations in the Southwest and the West), the increase in precipitation was offset by higher temperatures, causing more water to be evaporated.

The study made no mention of climate change, but it does illustrate the importance of making regional assessments of any climate change – the hydrology of different regions is different, and so the response to any changes in climate may differ too. The study also demonstrates that we can’t take a simple approach to predictions of drought, like saying more rain means less drought. The whole water cycle must be taken into account.