Through The Sandglass

Earth Science Week: "Geology helps the land tell you stories"

It's this year's Earth Science Week - see the American Geosciences Institute and Geological Society of London sites). I have periodically attempted to join the celebrations with posts on the "Nine big ideas" and the associated videos, Earth Science Literacy, and the outstanding "known unknowns" of earth science - please have a re-visit.

These were largely ruminations on what geology is about, the "philosophy" of the science, and a little advocacy for greater awareness. The question of why geology, what makes it fascinating, were subtexts, so my attention this year has been caught by a piece from September 2015 by Julia Turner, editor in chief of Slate. Titled "Your World, Rocked: A good introduction to geology course is actually a course in time," it is an eloquent (and personal) testimony to the value (sometimes not so obvious) of even a modest exposure to how our home planet works. It is, of course from the perspective of US education, but that matters not at all - its message is universal. The "rocks for jocks" amusement in the introduction is purely American - and so true. I taught Geology 101, otherwise known as "rocks for jocks" for several years, with many rewards and frustrations. Chief amongst the latter were the many kids who told me how much they enjoyed it, having had no idea at all about geology, and regretted that they were too far down their academic path (having left the science requirement until last) to pursue it further. I doubt that problem has gone away - to the loss of the science. There were many kids who were a joy to teach and interact with (although here I do not include the young woman who entered my office, closed the door, and declared that "Professor Welland, I'd do anything for an A"). But I digress....

In celebration of Earth Science Week, and in the hope that it might persuade just one young person to take a geology class, I am taking the liberty of reproducing in its entirety Julia Turner's piece from Slate:

A good introduction to geology course is actually a course in time.

By Julia Turner

Let me start by defending geology’s honor. Is there any other discipline that a rhyme so easily reduces to ridicule? Nearly every campus has some version of “rocks for jocks,” the intro geology course touted as the easiest way for granite-brained humanities majors to fulfill their science requirements without significant intrusion on their time or erosion of their GPAs.

But you shouldn’t take geology because it’s easy. (It isn’t necessarily easy—the geology class I took, from a bright-eyed elfin woman with the pleasing, rocklike name of Jan Tullis, certainly wasn’t.) You should take geology because it will fundamentally transform the way you see the world.

I mean this literally. Understanding geology gives you a new way to interpret the visual data of the planet. Sometimes this can feel like X-ray vision or a sixth sense. The color of the soil can tell you what it’s made of. The lightning bolts of white across that cliff the highway blasted through? Quartz veins, a sign of metamorphic activity, way back, when fissures opened up in bending, cracking stone, and mineral-laden water coursed through. Looking out of a plane window at the contours of a mountain range, you can tell from shape alone whether the peaks are old or new—or rather, which are very very old and which are just old. (It’s the opposite of human aging: cragginess is a sign of relative youth, and smoothness comes only with time.) And the words! Schist. Nickeliferous. Gneiss. Each one with its own dense poetry.

Geology helps the land tell you stories. I remember flying once and noticing funny little slab-like mountains, each one distinct from the next, lying in parallel rows. Where once I would have seen only mystery, now I could imagine how those mountains came to be—a sedimentary bed, layer upon flat layer of different types of rock, broken and thrust upward by the movement of the plates, revealing a cross section in which the softer rocks had eventually eroded away, leaving only these orderly little slabs.

Geology is a gorgeous way to contemplate the abyss.

But geology does more than give you something to think about when you examine pebbles on a beach or go swimming in a quarry. You should also take geology because there is no better way to gain perspective on the fleetingness of life. Any good intro geology course is actually a course in time. You’ve heard the statistic: If the whole planet has been around for a single 24-hour day, the dinosaurs showed up at 10:56 p.m. and we just before 11:59. But imagine spending hours holding that thought in your mind, learning what happened during all the time that preceded us. Understanding, in a real way, how long the planet has been around; how slow, patient, and indifferent the movement of the rocks beneath us has been; how insignificant in the scheme of things our fervid civilizations and wars and inventions really are—this is a head trip better than any you’ll experience during the concert at Spring Fling..

Taking geology actually had a funny side effect for me. I came into the class an avid environmentalist. I was a child of the ’90s. I cared about whales. I recycled. I spent a semester on a farm. I wanted to keep humans from changing and destroying the planet. But geology complicated my understanding of this desire. The planet has been changing for millennia. It’s been destroyed and remade again and again. The temperature used to be different. The continents were in different places. Different creatures roamed the land. The environmentalist instinct to preserve the planet exactly as it is began to seem not altruistic, but selfish. The planet is a tough cookie. This pile of rocks doesn’t need saving. What we were trying to save, it seemed, was the version of the planet that works best for ourselves. And, sure, future generations and all the other species that currently live here. Still a worthy goal, of course. Perhaps an even worthier one, when you consider how unusual and unlikely Earth’s menagerie is. But geology made me think about it in a new way.

College students often enter university with an outsized view of their own significance. It’s good to study things that make you realize how unimportant you are. As a history major, I took a lot of classes that helped me understand how small my life is in the span of human existence. But there are a few courses—geology, astronomy, perhaps particle physics—that force students to confront true vastness, that make you consider the insignificance not just of your life, but of your entire species. Geology is a gorgeous way to contemplate the abyss.

This is valuable, in the end, because it both helps you care less and makes you care more. What’s a bad day in the scheme of things? But then again, why not make each one count? Something to consider, next time you contemplate the contours of the land.

Indeed.

 

re the stunning image at the head of this post: 

Credit: NASA Goddard Space Flight Center Image by Reto Stöckli (land surface, shallow water, clouds). Enhancements by Robert Simmon (ocean color, compositing, 3D globes, animation). Data and technical support: MODIS Land Group; MODIS Science Data Support Team; MODIS Atmosphere Group; MODIS Ocean Group Additional data: USGS EROS Data Center (topography); USGS Terrestrial Remote Sensing Flagstaff Field Center (Antarctica); Defense Meteorological Satellite Program (city lights)

This spectacular “blue marble” image is the most detailed true-color image of the entire Earth to date. Using a collection of satellite-based observations, scientists and visualizers stitched together months of observations of the land surface, oceans, sea ice, and clouds into a seamless, true-color mosaic of every square kilometer (.386 square mile) of our planet. These images are freely available to educators, scientists, museums, and the public.

Much of the information contained in this image came from a single remote-sensing device-NASA’sModerate Resolution Imaging Spectroradiometer, or MODIS. Flying over 700 km above the Earth onboard the Terra satellite, MODIS provides an integrated tool for observing a variety of terrestrial, oceanic, and atmospheric features of the Earth. The land and coastal ocean portions of these images are based on surface observations collected from June through September 2001 and combined, or composited, every eight days to compensate for clouds that might block the sensor’s view of the surface on any single day. Two different types of ocean data were used in these images: shallow water true color data, and global ocean color (or chlorophyll) data. Topographic shading is based on the GTOPO 30 elevation dataset compiled by the U.S. Geological Survey’s EROS Data Center. MODIS observations of polar sea ice were combined with observations of Antarctica made by the National Oceanic and Atmospheric Administration’s AVHRR sensor—the Advanced Very High Resolution Radiometer. The cloud image is a composite of two days of imagery collected in visible light wavelengths and a third day of thermal infra-red imagery over the poles.

 

Sandscapes of the Mid-Atlantic Ridge

I have just returned from an utterly memorable two weeks in the stunning, extraordinary, landscapes of Iceland. I have never seen anything quite like it. Iceland is, quite simply, unique - and wonderful. There will undoubtedly be further bulletins, but for a start, a modest gallery.

(this, by the way, is the end of the lava flows from the 2014/2015 eruption of Bárðarbunga and Holuhraun in the central highlands)

and, after two weeks of daily practice and testing with a variety of patient Icelanders, I can now pronounce Eyjafjallajökull more or less correctly - if slowly.

Please read this

Erik Klemetti is an assistant professor of Geosciences at Ohio's Denison University and he writes Eruptions, a blog about all things volcanic for Wired. A few days ago, he put up the following which I sincerely hope will be taken to heart by untold numbers of students around the world.

Dear College Students: You Should Take Geology

GEOLOGY (OR, MORE properly these days, geosciences) is a field that most incoming first-year students have little experience with. Maybe they had a rock collection, maybe they took AP Environmental Science. Maybe, if they were lucky, they had a high school teacher with some training in the field. However, most of the time, geology is faaaaardown the list of disciplines that any first-year might think to study … and the field doesn’t even cross their mind before they graduate.

That, my friends, is a mistake. Few disciplines in today’s world play such a significant role in how society operates and what we can do to protect our future. Few fields of study can play such a profound role in protecting people’s lives on a daily basis, whether you realize it or not. And few can bring together so many disparate ideas, from sciences to social sciences to humanities to the arts, like the study of the Earth can.

And no, it isn’t “Rocks for Jocks.”

I’m looking specifically at you, Mr./Ms./Mx. “I don’t like science.” Science is all around you, and understanding how the planet on which you will (likely) spend the rest of your life is pretty important. You make decisions every day in which geology was a factor somewhere along the line, so if you are ignorant of those ideas, you might not be making the right decision.

So, what do I mean? Here are some of the ways that taking a course in the geology will impact your life for the rest of it.

Time: Humans tend to not be great about thinking on long timescales—that is, anything longer than maybe their own lifespan. In geology, that is a merely a flash compared to deep time. Deep time is the timescale that takes us back over 4.5 billion years to the formation of the planet. So, while 100 years might seem like a long time now, take a geology class and you’ll be thinking about events that happened 10,000 or 100,000 or 100,000,000 years ago … and that gives you perspective about events happening on our planet today.

Space: Geology is also a discipline that gets you to think about many scales of space. Need to understand the evolution of a continent? We got that. Need to think about how isotopes of an element go into a crystal when it forms? We got that too. Best part: You likely need both ends of the size spectrum to solve problems.

Observation: Many science fields are very theoretical (I’m looking at you, physics … with apologies to the astronomers). That’s great and all, but if all the equations aren’t your bag,* geology is chock full o’ observing. It is these observations that are the backbone of the field, both in looking at a static landscape like the folds in a mountain belt and at active processes, like a landslide or an eruption. Satellites have opened up a whole new world of observations that unlock geologic problems … and offer us tantalizing new ones to examine. The field is a visual one!

*author’s note: contrary to popular belief (at college), geology is not an “easy” science. We do math! We do chemistry! We do biology! We do physics! We do archeology! But if you’re in college to do stuff that’s easy, you’re doing it the wrong way.

Thinking globally: You can’t really avoid thinking about the planet when you study geology. Now, it might not be the surface of the planet—lots of geologists study parts of the Earth deep beneath our feet (I’m talking thousands of kilometers down)—but that’s OK. You’re still thinking on a global scale. Ocean circulation, volcanic ash in the air, plates colliding, earthquakes rattling the planet. All these things (and more) are processes that geologists contemplate on a global scale.

Getting outside: Best thing about thinking globally and wanting to observe the world? It gets you outside. Most geologists covet their time doing “field work” and if you are a geology major, you’re likely going to head off at some point to do “field camp” (where you learn the secrets of mapping the Earth) or “field research,” where you can make observations, collect samples, and think about geologic processes all while hiking some of the most spectacular landscapes. Places I’ve gone as a geologist include the high Andes of Chile, New Zealand, the Cascades in western North America, Hawaii, the coast of Maine, the deserts of California and much, much more.

Climate: Now, so far I’ve talked about all the fun parts of geology. However, if you’re looking for work that is important to you, your family and society across the planet, geology is the place to be. First off, geology is ground zero for understanding climate change across the history of Earth. We’ve been studying the variation in the planet’s ecosystems for two centuries now (heck, paleontology helped start the discipline) and can look back billions of years to see how the climate has varied. This gives us that evidence to show how much our current climate is likely in a state of distress. Geology is also how we can understand what the impact of climate change will be on our planet, both in the short- and long-term.

Hazards: If you take geology, you’ll find out about all the ways the planet might be trying to take you out: eruptions, earthquakes, landslides, floods, sinkholes, tsunamis, and more. You’ll also learn how geologists are trying to protect people from perishing in such disasters by better understanding their impacts and assessment of their risk to lives and property. More importantly, you’ll realize how to protect yourself. Buying a house? Maybe you should check to see if you’re on a floodplain. Is the house in an earthquake-prone area? Is the hillslope stable behind the place? Geologic hazards will impact you at some point, so understanding them puts you ahead of the curve.

Resources: Take a look around you right now. I’d venture to say that much of what you see came from a geologic deposit at some point. Copper wires? Maybe from the copper deposits of the Andes. Steel for your car’s frame? Maybe Minnesota. Your iPhone is chock full of rare earth elements that likely came from Chinese carbonatite deposits. The power for your house may be coming from a range of geologic resources: coal (yes, sadly) or uranium (better) or hydro-power. If you study geology, you’ll start to realize the impact that extracting these resources has on the planet (and people) so you can make more sustainable decisions. You might even get a job in geologic resources (and trust me, it is profitable—a practical reason to take geology: to get one of the many high-paying entry level jobs out there).

Synthesis: However, to me, one of the key reasons to take geology is to start thinking about lots of ideas all at once and begin to synthesize the information. If you really want to understand the hazards posed by a volcano, you’ll need to understand magmatic processes that form the magma and allow it to erupt, how that stuff that erupts moves across the Earth’s surface, what people might be living near the volcano, and how it might be best to communicate the hazard to them. Geology has so many intersections across so many disciplines that a background in geology will allow you to intelligently speak about everything from the age of the planet to the potential of an earthquake in your hometown to how animal life has changed in Ohio for the last billion years.

Geology is so central to the lives of so many people. If the goal of college is to create an informed citizenry that can then navigate their lives, a background in geology (even if it might be a single class) might be one of the most important disciplines you could choose. So, if you’re never considered taking that geology class offered on your campus, now might be the time to give it a try. You’ll come out realizing our place in the planet’s long history.

I’m sure I haven’t even scraped the surface, so do you have any more great reasons to take geology?

Thanks, Erik!

The image at the head of this post, in keeping with Erik's volcanic passions, is from Iceland, 2015: the eruption of Holuhraun, courtesy of NASA's Earth Observatory. This is of particular interest to me, since I'm off to Iceland tomorrow (Katla willing) and among the destinations on my itinerary is Askja volcano which, in the cloud and the snow, can be seen 19 kms directly north of the eruption in the NASA image. Exciting, huh? Just hope the weather and lithospheric turbulence don't spoil the fun...

 

"No one actually studies sand" - misconceptions and science literacy

 

For one reason or another (likely to be discussed in a future post), I have been working on an essay that attempts to address cross-cultural aspects of viewing and valuing the land and reviews the potential implications for learning geoscience through integrating "geomythology" (a less than perfect term) into the process.

Coincidentally, in the course of seemingly endless research and reading, I came a across a fascinating geoscience education story on sand. In 2014, the American National Association of Geoscience Teachers published two fascinating issues on the theme of "Teaching Geoscience in the Context of Culture and Place," full of provocative discussion and ideas. In the second issue, one particular paper caught my attention: "Where Are You From? Writing Toward Science Literacy by Connecting Culture, Person, and Place," written by Kanesa Duncan Seraphin from the Curriculum Research & Development Group and the Center for Marine Science Education, University of Hawai'i. As she writes in her abstract:

The ways in which people view the world, and by extension the ways in which they learn, are shaped by cultural context. As educators striving to build scientific literacy among our students, it is critical to bridge the gaps among disparate cultures, traditional ways of knowing, and Western science. Understanding the value of traditional knowledge and welcoming the discourse and novel viewpoints associated with cultural and place-based practices is the first step in opening the door of scientific literacy not only for indigenous students but also for students struggling to find personal relevance in science.

She discusses the disconnects in today's world between science and culture that can "distract students from effectively learning" and goes on to discuss "Activities that connect sense of place and person provide opportunities for students to learn about and integrate the human element of science with scientific research and discovery." Her focus is on personal writing that 

helps students take ownership of their learning and facilitates students’ learning awareness. Writing provides a space for students to connect with their culture and their thoughts—to think about what they know and believe, thereby promoting metacognition and purposeful knowledge generation. Writing also promotes scientific literacy by improving synthesis skills through the construction of a written record.

Among the examples she discusses is a wonderful example of the results of place-based learning by high school teachers taken first to the beach and then to the lab to pursue experimental enquiry through personal connections. The original exercises are described here, in what is, in itself, an excellent and valuable report well-worth reading). However, it's what Seraphin includes as feedback from the students that I found particularly intriguing. In their writings, the students were encouraged to record what they "used to believe" about sand and subsequently recognised as misconceptions following the learning process. Here they are:

See why I found this so fascinating? As Seraphin comments:

This type of feedback is an important information-gathering step for teachers and an important learning step for students. It also reflects the ability of writing to engage students in the learning process by providing the space and freedom for learners to express what they think (or used to think) without fear of failure.

and in her conclusions

The working hypothesis is that enhancing place and personal connections in science teaching will improve students’ self-efficacy and attachment to science learning, thereby leading to increased retention in science courses, higher test scores, better grades, and higher-quality student work. Writing often and with cultural, and place-based, relevance is therefore recommended as a thinking tool to personally and contextually connect the past, present, and future aspects of teaching and learning.

"Hear, hear" is all I can say.

 

A Reverence for Rivers (3): Piling up a heritage of conflict and litigation over water rights

 

We only have ONE hydrologic system, dammit!

School kids know that (it's in all their textbooks), geologists, geophysicists, geomorphologists, environmental scientists and ecologists, climatologists and meteorologists, resource scientists, most engineers, and a hell of a lot of people on the street know that. It is, however, a fact that seems to have escaped multitudes of politicians, policy-makers, regulators, at least one US presidential candidate, and, of course, commercial enterprises - whether out of profound and inexcusable ignorance or under the influence of vested interests and lobbies is open to question.

But it remains a fact. The entire hydrologic system - rain drops, clouds, springs, creeks, rivers, lakes, snow, ice, run-off, evapotranspiration and groundwater - is interconnected. Mess about with one bit and other parts will be affected - it's complex, but it is one single system.

The title of this post is a quotation from John Wesley Powell, a voice of knowledge and rationality that we could benefit from today - more of that, quite possibly, in a future post. Over 120 years ago, addressing an audience of (booing) vested interests in irrigation at any cost, he said:

When all the rivers are used, when all the creeks in the ravines, when all the brooks, when all the springs are used, when all the reservoirs along the streams are used, when all the canyon waters are taken up, when all the artesian waters are taken up, when all the wells are sunk or dug that can be dug, there is still not sufficient water to irrigate all this arid region.  I tell you, gentlemen, you are piling up a heritage of conflict and litigation over water rights, for there is not sufficient water to supply these arid lands.

This occasional series, A Reverence for Rivers, is dedicated to Luna Leopold and perhaps I should add John Wesley Powell. In a the previous episode I quoted from a piece, written over sixty years ago by Leopold and his colleague Harold Thomas:

There are enough examples of streamflow depletion by ground-water development, and of ground-water pollution from wastes released into surface waters, to attest to the close though variable relation between surface water and ground water.

Man has coped with the complexity of water by trying to compartmentalize it. The partition committed by hydrologists—into ground water, soil water, surface water, for instance—is as nothing compared with that which has been promulgated by the legal profession, which has on occasion borrowed from the criminal code to term some waters "fugitive" and others, a "common enemy." The legal classification of water includes "percolating waters," "defined underground streams," "underflow of surface streams," "water-courses." and "diffuse surface waters"; all these waters are actually interrelated and interdependent, yet in many jurisdictions unrelated water rights rest upon this classification.

This jurisdictional and regulatory problem of compartmentalization of water resources contrary to the facts of the way the system works has given rise to many of the profound problems we face today. So I thought it might be helpful to set out some of the facts of the relationships between ground and surface waters and the consequences of ignoring them - bear with me, this may be a summary but it's not going to be short!  

First, the interested reader can do no better than to go (as is so often the case) to the USGS. Published nearly 20 years go, Circular 1139 is titled Ground Water And Surface Water: A Single Resource. The synopsis is as follows:

As the Nation's concerns over water resources and the environment increase, the importance of considering ground water and surface water as a single resource has become increasingly evident. Issues related to water supply, water quality, and degradation of aquatic environments are reported on frequently. The interaction of ground water and surface water has been shown to be a significant concern in many of these issues. For example, contaminated aquifers that discharge to streams can result in long-term contamination of surface water; conversely, streams can be a major source of contamination to aquifers. Surface water commonly is hydraulically connected to ground water, but the interactions are difficult to observe and measure and commonly have been ignored in water-management considerations and policies. Many natural processes and human activities affect the interactions of ground water and surface water. The purpose of this report is to present our current understanding of these processes and activities as well as limitations in our knowledge and ability to characterize them.

USGS Circular1376, published in 2012, incorporated material from 1139 and proceed to document in considerable detail Streamflow Depletion by Wells—Understanding and Managing the Effects of Groundwater Pumping on Streamflow. Again, a straightforward summary:

Groundwater is an important source of water for many human needs, including public supply, agriculture, and industry. With the development of any natural resource, however, adverse consequences may be associated with its use. One of the primary concerns related to the development of groundwater resources is the effect of groundwater pumping on streamflow. Groundwater and surface-water systems are connected, and groundwater discharge is often a substantial component of the total flow of a stream. Groundwater pumping reduces the amount of groundwater that flows to streams and, in some cases, can draw streamflow into the underlying groundwater system. Streamflow reductions (or depletions) caused by pumping have become an important water-resource management issue because of the negative impacts that reduced flows can have on aquatic ecosystems, the availability of surface water, and the quality and aesthetic value of streams and rivers.

Both of these publications should be required reading for anyone, anywhere who is even remotely involved in water management and policy-making.

So let's start with a simple and fairly self-explanatory image from the USGS:

Ground-water flow paths vary greatly in length, depth, and travel time from points of recharge
to points of discharge in the groundwater system.

Groundwater, streams and wells all interact and influence water flow, but the rates of that flow vary over several orders of magnitude, from days to millennia. The architecture and physical characteristics (permeability and so on) of the aquifer system are always complex in reality and the distribution of lower permeability (confining) layers will dramatically influence the direction, amount, and rate of flow. 

In places where the water table "outcrops" - i.e., intersects with the surface - there will be a spring (as at Havasu Falls, the image at the head of this post, ultimately feeding the Colorado River), a lake or groundwater feeding the flow of a river through its bed and banks. The relationship between the water table and a body of surface water is critical - a stream can be "gaining" flow from groundwater discharge or "losing" it by flow into the water table (depletion):

Groundwater discharge into streams and rivers is commonly the major contribution to their flow which is only augmented by rainfall and surface runoff.

Different segments of a river or stream may be typically gaining or losing and this will vary with the season - if the water table falls, the river may become "disconnected" from the water table, or, in times of flood, the river level may rise higher than the water table and effectively charge storage in its banks until the level falls back to normal.

All these variations occur quite naturally depending on time and place, and the system may be stable for long periods of time. But start pumping groundwater in the vicinity of a river and the system is de-stabilized. As the caption to this next USGS illustration describes, "In a schematic hydrologic setting where ground water discharges to a stream under natural conditions (A), placement of a well pumping at a rate (Q1) near the stream will intercept part of the ground water that would have discharged to the stream (B). If the well is pumped at an even greater rate (Q2), it can intercept additional water that would have discharged to the stream in the vicinity of the well and can draw water from the stream to the well (C)."

 To quote again from the USGS:

The first clear articulation of the effects of groundwater pumping on surface water was by the well-known USGS hydrologist C.V. Theis. In a paper published in 1940 entitled "The Source of Water Derived from Wells," Theis pointed out that pumped groundwater initially comes from reductions in aquifer storage. As pumping continues, the effects of groundwater withdrawals can spread to distant connected streams, lakes, and wetlands through decreased rates of discharge from the aquifer to these surface-water systems. In some settings, increased rates of aquifer recharge also occur in response to pumping, including recharge from the connected surface-water features. Associated with this decrease in groundwater discharge to surface waters is an increased rate of aquifer recharge. Pumping-induced increased inflow to and decreased outflow from an aquifer is now called "streamflow depletion" or "capture."

So there is a critical interaction between groundwater and surface water by complex flows that take place over days, centuries and millennia, and wells can cause major changes to that interaction - streamflow can be severely depleted, water tables lowered and aquifer water volume maintenance totally disrupted. 

For here is the first of what USGS Circular 1376 intriguingly documents as "common misconceptions." That is: 

Misconception 1. Total development of groundwater resources from an aquifer system is “safe” or “sustainable” at rates up to the average rate of recharge.

This is fundamental, because we hear all the time that aquifers are being "mined" as a result of volumes pumped exceeding the recharge rate from rainfall up in the hills - it's really not as simple as this. Because streams and rivers are frequently depleted by losing water to an aquifer, particularly when wells are pumping from that groundwater supply, it is this source that is the dominant way in which an aquifer is recharged, not by water from the hills. 

The sources of water to a well are reductions in aquifer storage, increases in the rates of recharge (inflow) to an aquifer, and decreases in the rates of discharge (outflow) from an aquifer. The latter two components are referred to as capture. In many groundwater systems, the primary components of capture are groundwater that would otherwise have discharged to a connected stream or river in the absence of pumping (referred to as captured groundwater discharge) and streamflow drawn into an aquifer because of the pumping (induced infiltration of streamflow)...

Reductions in aquifer storage are the primary source of water to a well during the early stages of pumping. The contribution of water from storage decreases and the contribution from streamflow depletion increases with time as the hydraulic stress caused by pumping expands outward away from the well and reaches one or more areas of the aquifer from which water can be captured. At some point in time, streamflow depletion will be the dominant source of water to the well (that is, more than 50 percent of the discharge from the well) and after an extended period of time may become the only source of water to the well. The time at which streamflow depletion is the only source of water to a well is referred to as the time to full capture.

So, if you choose to define and manage, through regulation and policy, groundwater and surface water as two entirely separate systems, you choose a recipe for disaster - you are more often than not severely double-counting and thereby overestimating your resources and you are not managing the system at all. And yet this is exactly what California, Arizona and, indeed, all the arid States of the Western US (not to mention other States and other countries) have been doing for more than a century. This has been superbly documented in ProPublica's piece, "Less Than Zero: Despite decades of accepted science, California and Arizona are still miscounting their water supplies." That analysis, part of their extensive "Killing the Colorado" series of reports, has also been summarised in the New York Times:

John Bredehoeft, a leading hydrogeologist and former director of the federal government’s Western states water program, bluntly emphasized the importance of basic honesty in counting water.

“If you don’t connect the two, then you don’t understand the system,” he said. “And if you don’t understand the system, I don’t know how in the hell you’re going to make any kind of judgement about how much water you've got to work with.”

Until state officials do, it seems unlikely that there will be any real solution to managing the Southwest’s strained water resources for the future.

But there's another, fundamental, problem - if you can't measure, monitor, document, you can't manage - and the data are essentially not there to measure, monitor and document. For example, California, again from the New York Times:

Although the state has not updated the surveys in the last three decades, the Department of Water Resources recently reported that across most of the state groundwater levels have dropped 50 feet below historical lows, with levels in many areas in the San Joaquin Valley more than 100 feet below previous historic lows.

In California, the state’s water agency has said that the failure to account for how groundwater withdrawals affect the state’s rivers is a major impediment to a true accounting of its resources. In April [2015], authorities reported that less than half of the state’s local water agencies had complied with a 2002 law that made them eligible for state funds only if they set up groundwater management plans and determined if a connection between surface water and groundwater existed. That connection does not exist uniformly and varies depending on local geology. Only 17 percent of the state’s groundwater basins had been examined.

Indeed, California still doesn't require that water pumped from underground be measured at all, much less factored into an overall assessment of total water resources; it’s merely an option under a new law signed last September.

California’s new groundwater legislation does require local water authorities to come up with sustainable groundwater plans, but they don’t have to do that until 2020, and they don’t have to balance their water withdrawals until 2040.

To all intents and purposes, the only way we have to analyse these issues is through computer modelling - very clever and sophisticated, but, at the end of the day it is modelling, not analysis of real-world data. But assembling meaningful real-world data is not easy on a local scale and the time-frame of aquifer behaviour is a long one. Make your way through USGS Circular 1376, and you will find several regional-scale analyses of groundwater/streamflow interaction based on the statistical analysis of data, and the authors document in detail the challenges of field studies, stating that

Statistical studies such as these can be used in general to evaluate the large-scale effects of basinwide pumping on streamflow reductions. They cannot, however, account for the specific effects of pumping at individual wells, nor can they help with understanding how specific management actions might affect future depletion. Such analyses require the use of analytical or numerical models.

So we are largely stuck with modelling. It is, nevertheless, a powerful tool, and several examples are presented in the USGS document. Since we are particularly interested in water and arid lands, here is a very relevant - not to mention fascinating, sobering, and perhaps surprising - example. The situation, that of a hypothetical desert-basin aquifer with a through-flowing river along the east side of the basin, is summarised here (remember that 1 acre-foot of water equals 1233 cubic meters):

There is natural recharge from the west and, under natural conditions, inflow from the river to the aquifer in the north and outflow from the aquifer to the river further downstream. Two wells are drilled into the aquifer, one five miles from the river, the other ten. Each well then pumps at a rate of around 750,000 cubic meters per year, and continues to do so for 50 years when pumping then ceases. The analysis treats each well separately - they are not both pumping at the same time. So let's consider the effects of streamflow of the well closer to the river (but still five miles away). What we are looking at are plots of the resulting increase in flow from the river into the aquifer, decrease in flow into the river from the aquifer and the total changes to river flow (depletion):

Over the period of pumping, the river's flow is decreased by almost 25%, depriving downstream users of water. After pumping stops, the river's flow begins to recover - but note the timescale: the river has still not returned to its natural flow rate after 150 years. And nearly half of the total volume of depletion will occur after pumping stops. The effects of the more distant well are only slightly more modest - but they last much longer and the maximum depletion occurs several years after the well stops pumping.

Now this "hypothetical desert-basin aquifer" may remind you of somewhere - the Ranegras Valley of Arizona, perhaps? Where the Saudi conglomerate, Almarai, are growing alfalfa for export back home? Except that this hypothetical example only covers the effects of one well pumping: Almarai operate 18 wells, each one capable of pumping 4 or 5 times the lonely well in our hypothetical desert valley, and they have received permission to drill 8 more.

Now of course there is no flowing river in the Ranegras Valley, but there is Brouse Wash, ephemeral, yes (although prone to flash flooding), but clearly with water not far below the surface, given the vegetation and the occasional stock pond visible on Google Earth:

So the Brouse River probably flows just below the surface of the wash, and, if it flows at all, will not be doing so much longer as its water supplies the alfalfa.

The Brouse does, I believe, eventually supply modest volumes of water to the Colorado, and, interestingly, while I was researching and preparing this post, Matthew Miller and his colleagues at the USGS published a paper titled "The importance of base flow in sustaining surface water flow in the Upper Colorado River Basin", summarised by Science Daily. The research covered the upper Colorado basin (i.e. upstream from Lee's Ferry and the Grand Canyon) where 90% of the river's flow originates and the work documents that 60% of that flow is provided by groundwater. Subsequently, more than 80% of that groundwater is lost, by evapotranspiration and diversion for irrigation, before it reaches the lower river (where, amongst other problems, Lake Meade has recently been reported to be at its lowest level ever). The abstract for the paper puts it very succinctly:

The Colorado River has been identified as the most overallocated river in the world. Considering predicted future imbalances between water supply and demand and the growing recognition that base flow (a proxy for groundwater discharge to streams) is critical for sustaining flow in streams and rivers, there is a need to develop methods to better quantify present-day base flow across large regions....

Our results indicate that surface waters in the Colorado River Basin are dependent on base flow, and that management approaches that consider groundwater and surface water as a joint resource will be needed to effectively manage current and future water resources in the Basin.

Or, as Matthew Miller himself is quoted as saying, "In light of recent droughts, predicted climate changes and human consumption, there is an urgent need for us all to continue to think of groundwater and surface water as a single resource."

It couldn't have been put better - if you have made it through this post, thank you! And many thanks, as always, to the USGS.

Camels don't fly, deserts don't bloom

 

Back in November last year, I described how, very controversially, Arizona is exporting its water in vast quantities to Saudi Arabia, via alfalfa to feed Saudi cattle. In that post I quoted from the work of Elie Elhadj, who has compellingly documented the rape of the Kingdom's groundwater resources:

In 2004, Elie Elhadj of the School of Oriental and African Studies (SOAS), King’s College London published a blunt analysis of the extraordinary history of the destruction of the country’s water supplies. Titled “Camels Don’t Fly, Deserts Don’t Bloom: an Assessment of Saudi Arabia’s Experiment in Desert Agriculture” the report paints a catastrophic picture.

That experiment in desert agriculture is now essentially over, and Saudi Arabia relies almost entirely on imports of crops and cattle feed. In order to satisfy this need, the country's huge food and agriculture business, Almarai, buy farming land elsewhere in the world - including in the Arizona desert. Since I wrote that post, Almarai have added to their assets by buying land on the other side of the Colorado River in south-eastern California. Both California and Arizona are now in their fourth year of severe to exceptional drought.

After I quoted from his work, Elie contacted me and we commenced an email conversation that led to a fascinating and highly enjoyable meeting and discussion. He told me that he was in touch with a group of students at Arizona State University who were making a short video on the issues of exporting water to Saudi Arabia, and that video is now on line - it's extremely well done and worth watching:

Camels Don't Fly, Deserts Don't Bloom from Cassie Ronda on Vimeo.

There is an interesting cast of characters (in addition to Elie Elhadj himself): local residents who have seen the water levels in their wells drop 50 feet in four years, a lawyer for Almarai who, when talking about any link between water problems and agriculture, cheerfully states that "I don't think that's the case", local people agreeing that some form of regulation is needed as long as their water usage is not regulated, and Kathleen Ferris of the Morrison Institute for Public Policy at Arizona State, who comments that "It's almost impossible to manage groundwater without some kind of regulation." Such a statement may seem blindingly obvious, but the fact is that, in La Paz County Arizona there are no regulations whatsoever - anyone can arrive, drill as many wells as they want, and deplete the groundwater resources to whatever extent pleases them. 

This is madness. Consider the likely reaction of our old friend the alien scientist, flitting around the earth on a resource analysis mission and observing this scene:

 

"Wait a minute. There's the huge canal that they built to take water from the dwindling and over-exploited flow of the Colorado River, specifically to supply the city of Phoenix where groundwater supplies had been drastically depleted, and, right next to it are fields of water-sucking alfalfa grown to be exported as feed for Saudi cattle - this is no way to run a planet."

Yes, this may be madness for Arizona and California, but it's only part of a global-scale pattern of unsustainable insanity - and we should not be quick to judge Arizona. In a recent issue of the New Scientist, there was an interview with Arjen Hoekstra, a professor of water management at the University of Twente, in the Netherlands, and founder of the Water Footprint Network. Hoekstra and his colleagues have developed a careful and extensive method of measuring water footprints, expressed as per capita usage country-by-country, and allocating the proportion of blue, green and gray water:

The WF is a measure of humans’ appropriation of freshwater resources and has three components: blue, green, and gray. The blue WF refers to consumption of blue water resources (surface and ground water), whereby consumption refers to the volume of water that evaporates or is incorporated into a product. The blue WF is thus often smaller than the water withdrawal, because generally part of a water withdrawal returns to the ground or surface water. The green WF is the volume of green water (rainwater) consumed, which is particularly relevant in crop production. The gray WF is an indicator of the degree of freshwater pollution and is defined as the volume of freshwater that is required to assimilate the load of pollutants based on existing ambient water quality standards.

 The title of the interview is "We can avoid a water crisis, but the fix will be hard to swallow" and, when asked "How is the UK doing in terms of water use?", he replied:

Because it imports so many goods, three-quarters of the UK’s water consumption is actually outside of its borders. And about half of that usage is not sustainable. For example, the UK imports rice and olives from southern Spain and sugarcane from Pakistan, regions where water is overexploited. This means groundwater levels are declining and rivers dwindling or drying up. That’s bad news for the exporting countries and for the UK, because these food sources will ultimately fail.

In terms of the broader region, Europe is the biggest net importer of water-intensive commodities in the world, much of it from water-scarce regions. In fact 40 per cent of Europe’s water footprint is outside the continent. A large part of that is unsustainable.

So let's not get too smug about Arizona, but, rather, worry about the large-scale problem. In terms of water footprint, domestic use is only a small part of the total - in Europe, the average consumer’s domestic use is typically only 1 to 2 per cent of their total water footprint. It's agriculture, what food we demand, where we choose to get it from, and how much we're prepared to pay for it that is the overwhelming factor. As Hoekstra comments

All food has a big water footprint, because agriculture is the largest water consumer. Grains generally have a water footprint in the order of 1000 litres per kilogram. Beef is, on average, 15,000 litres per kilogram. Both are big numbers but you can see that meat is in a league of its own. So your diet, and particularly how many animal products you eat, has a big impact on your personal water footprint.

Take a look at that link - it's at the same time fascinating and alarming.

But it's the blue water footprint that is of particular interest here and, fortunately, in one of his publications, Hoekstra breaks down specifically the blue water footprint by country and internal versus external, i.e., indigenous versus imported. Take a look at the whole, intriguing, paper where the graph appears in the supplementary materials. I have cropped the complete graph to start with the UK on the left and highlighted the UK, China, the US, Spain, Pakistan, and Saudi Arabia - plus the world average in green.

Blue water footprint of national consumption for countries with a population larger than 5 million, shown by internal and external component (cubic meter per year per capita,1996–2005)

Take a good look at this graph and think through the overwhelming complexity of the issues. Countries whose footprint is relatively small may be dominantly importing other peoples' water - take the UK, for example. Countries whose footprint is large may be mainly consuming their own water but depleting and exporting it (see the US for example). There's an incredible set of questions and issues embedded in this graph, and add to this, overlay, Hoekstra's illustration of just the major global water flows:

Virtual water balance per country and direction of gross virtual water flows related to trade in agricultural and industrial products over the period 1996–2005. Only the biggest gross flows (>15 Gm3∕y) are shown.

By this measure, the US is not a net water importer. But then how much of its own water does it export? And then look at Europe.

I'm going to leave it there - you could write a book about it. In fact, Hoekstra has. To say that this is a thorny problem is a massive understatement - arguably has the makings of shorter-term crisis than climate change. What can we do about it? Well, in Hoekstra's words from the New Scientist interview, the fix can be hard to swallow:

We in northern Europe should realise that we are actually quite well off with water, and ask why we import water-intensive goods from water-scarce areas. It doesn’t make sense that we produce so little of our own food.

Isn’t this an inevitable effect of global markets?

Yes. We lose our own agriculture because elsewhere you have free water, cheap land, cheap labour. But it is not truly cheap; it is at the expense of the people over there, their land and their water. And in the long run, our own food supply is at risk. We need to change the rules of the market by discriminating in favour of sustainable production. It is a global challenge for agriculture, power generation, trade and economics, which we must work together to address. It’s a big deal, and it will only get bigger.

Our societies need to think long and hard about this - and read Hoekstra's latest paper: "Four billion people facing severe water scarcity."

 

Sand wars continue, unabated

It just doesn't stop, and the scale of the damage to communities and the environment is staggering.

NASA recently released the pair of images, above, showing changes to the sediment system of Poyang Lake and its rivers. The lake, these days much diminished in size, was once the largest freshwater lake in China, its water feeding into the Yangtze and providing an important haven for migrating birds. But when, in 2000, China shut down sand mining along the middle and lower Yangtze, the activity, legal and illegal, simply moved to Ponyang. The image on the left was acquired in 1995, the one on the right in 2013. The scale of devastation is obvious - try the "image comparison" feature for drama. 

The text accompanying the images describes the problem here (and elsewhere) in depressing detail:

When you see the vast expanses of sand in the Sahara and other major deserts, it is hard to comprehend how sand could ever be a resource in short supply. Yet for certain types, the supply of sand is indeed short.

For the construction industry, river and lake sand is more desirable than desert and ocean sand. To produce mortar for cement, concrete, and other building materials, the angular sand particles found in rivers and lakes are most useful. Making a strong mortar with the particles found in deserts—which are rounded by winds—is more challenging because the sand does not bind together as well. Likewise, ocean sand is mixed with salt, which can cause metals to corrode. Washing this marine sand can be time-consuming and expensive.

Over the past few decades, the global demand for construction sand has boomed, especially in Asia due to rapidurbanization. In China alone, the demand for cement has increased 438 percent over the past two decades,according to the United Nations Environmental Program.

In 2000, dredging and other sand mining become so intensive along the Yangtze River that Chinese authoritiesbanned the activity along the lower and middle reaches of the river. This drove many sand mining operators to Poyang Lake, a large body of water that flows into the Yangtze about 600 kilometers (400 miles) upstream ofShanghai.

This pair of false-color images captured by Landsat satellites shows the impact of sand mining on the northern reaches of Poyang Lake. The top image was acquired by the Thematic Mapper on Landsat 5 on December 7, 1995; the second image shows the same area as observed by Landsat 8’s Operational Land Imager on December 24, 2013. Water levels vary throughout the year at Poyang Lake, with the lowest levels occurring in winter.

By contrasting the two images, we can see dramatic changes in the outlet channel that connects Poyang Lake to the Yangtze river. Sand removal and dredging have deepened and widened the channel significantly. These activities also have left the remaining sandbars and shores with an irregular, serrated appearance. Turn on the comparison tool to see the changes.

As part of an effort to assess the scale of the sand mining and its environmental impacts, a group of researchers analyzed data collected by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor on NASA’s Terra satellite. Using infrared data collected by ASTER in 2005, the researchers found that the lake was producing up to 236 million cubic meters of sand per year—about 9 percent of the total produced by China. The researchers estimated that the volume of sand removed was probably enough to make Poyang Lake the largest sand mining operation in the world.

“Sand mining has compromised the ecological integrity of the lake by contributing to less predictable seasonal water fluctuations and to a series of recent low water events,” said James Burnham, an ecologist with the University of Wisconsin and the International Crane Foundation. Burnhan has conducted field research on wintering waterbirds at Poyang Lake. “This is a lake that hosts 98 percent of the endangered Siberian Cranes and Oriental White Storks, as well as a significant number of over a dozen other endangered waterbirds in the winter.”

Google "sand" and news and, among the entertaining images of sand sculptures and odd reports such as the discovery of hundreds of kilos of marijuana buried in the dunes of South Padre Island, Texas, you will find, every day, endless reports of the issues of sand mining around the world. A sampling:

Vietnam, Nepal, India (endless problems, mafias, crime), Cambodia, Singapore and Malaysia, the list goes on. The issues raised by the documentary, Sand Wars, have also been taken up by The Smithsonian, the United Nations, Wired, and Coastal Care. Numerous TV and radio programmes have covered the topic. And yet so few people are aware of it, and it just goes on and on.

 

Sunbathing in the microscopic desert jungle

The desert has its own palette, distinctive and at the same time subtle yet dramatic. There are many factors at work creating the patterns and hues of arid lands - obviously the kind of sand, the kind of rock, the vegetation, minerals and salts, desert varnish - but there are also artists at work that we can't see and barely understand: microbial communities.

We can see the mosses and the lichens, but the vast ecosystem of bacteria and fungi operates essentially invisibly; we are only beginning to scratch the surface of the desert to reveal the ubiquity and importance of microbial life in environments we often describe as "lifeless." These are communities labelled "cryptic" by biologists, a useful term disguising the fact that they are something we really don't understand very well. I found this definition helpful, from a piece in Nature a few years ago titled "Body doubles" by Alberto G. Sáez and Encarnación Lozano:

Have you ever approached someone whom you thought you knew, talked to him with familiarity, only to find out later that he was a complete stranger, albeit remarkably similar in appearance to the person you had in mind, such as a twin brother? Well, taxonomists are similarly puzzled when they come across two or more groups of organisms that are morphologically indistinguishable from each other, yet found to belong to different evolutionary lineages. That is, when they discover a set of cryptic species.

The microscopic cryptic communities of arid lands form the well-known "desert" or "cryptobiotic" crusts that we now realise play key roles in the ecosystem, cycling carbon dioxide and nitrogen, providing resources for plant life, controlling drainage and the hydrologic behaviour of the soil, and reducing erosion - and hence, atmospheric dust. 

Among the leading researchers shedding light on these cryptic communities is Ferran Garcia-Pichel at Arizona State University's School of Life Sciences. For example, in 2013, togather with international colleagues, he published a paper titled "Temperature Drives the Continental-Scale Distribution of Key Microbes in Topsoil Communities." Science summarises the work as follows:

Soil microorganisms make up a substantial fraction of global biomass, turning over carbon and other key nutrients on a massive scale. Although the soil protects them somewhat from daily temperature fluxes, the distribution of these communities will likely respond to gradual climate change. ... [We] surveyed bacterial diversity across a range of North American desert soils, or biocrusts—ecosystems in which photosynthetic bacteria determine soil fertility and control physical soil properties such as erodability and water retention. Most of the sites were dominated by one of two cyanobacterial species, but their relative proportions were controlled largely by factors related to temperature. Laboratory enrichment cultures of the two species at different temperatures also showed temperature as a primary determining factor of bacterial diversity. It is unknown if temperature will affect the distribution of other soil microorganisms, but the marked shifts of these two keystone bacterial species suggest further change is in store for these delicate ecosystems.

The work, only available behind the Science paywall, was helpfully reported by Live Science. The two dominant "keystone" bacterial species are  Microcoleus vaginatus and M. steenstrupii, the former preferring cooler conditions whereas the latter likes things hot. As temperatures vary, things become competitive and warming conditions result in the mysterious steenstrupii taking over. Now, because these communities are microscopic and cryptic, we can only measure such effects - and detect which organisms are in the soil - through sophisticated DNA analysis. It is further results of this kind of painstaking and careful work that Garcia-Pichel and his colleagues have just published in Nature. With Estelle Couradeau, also at Arizona State, as the lead author, the paper describes - startlingly - how "Bacteria increase arid-land soil surface temperature through the production of sunscreens." Microcoleus vaginatus and M. steenstrupii are far from alone, and, amongst their companions are tribes of cyanobacteria such as the hundreds of species belonging to the genera Scytonema and Tolypothrix. These little critters dislike the sun and apply a biosynthetic sunscreen, scytonemin, an alkaloid pigment that strongly absorbs solar radiation and dissipates this energy as heat. This sunscreen can be seen as patches of darker colour covering areas of desert crust, as in this photo by Garcia-Pichel from the recent report on Science Daily.

This pigmentation may protect some members of the bacterial community, but it can locally warm up the surface by as much as 10 degrees C (18 degrees F). This has a dramatic effect on the health of the cool-loving Microcoleus vaginatus, but is welcomed by M. steenstrupii, who come to dominate as the sunscreen develops, at the expense of vaginatus. As Garcia-Pichel comments:

... we can show that the darkening of the crust brings about important modifications in the soil microbiome, the community of microorganisms in the soil, allowing warm-loving types to do better. This warming effect is likely to speed up soil chemical and biological reactions, and can make a big difference between being frozen or not when it gets cold... On the other hand, it may put local organisms at increased risk when it is already quite hot.

And this has to be happening on a global scale. As Estelle Coradeau suggests, "Because globally they cover some 20 percent of Earth's continents, biocrusts, their microbes and sunscreens must be important players in global heat budgets. We estimate that there must be some 15 million metric tons of this one microbial sunscreen compound...warming desert soils worldwide."

But because we have only a poor understanding of what exactly these desert crusts are and how they work, their roles in local ecology and global systems are impossible to define. It is only through the meticulous work of Ferran Garcia-Pichel and his team, together with others such as Jayne Belnap of the USGS in Moab, Utah, that we can begin to unravel the extraordinary nature and contributions of these long-ignored microbial desert communities. As Belnap has commented:

These are the only game in town to prevent dust storms and erosion, so they're really, really critical parts of this ecosystem. Yet we've never asked the question, 'who's really in there, and what's going to happen there as things shift?'

and, as reported in a piece on Belnap in High Country News, the palette and patterns of our arid lands owe much to an invisible living world: 

She also remains convinced that the dark shadows on the desert are the true — and fragile — foundation of the Colorado Plateau. "Whenever we pull on the thread of what makes the system tick," she says, "we end up with soil crusts on the other end."

[See also Belnap's USGS site at www.soilcrust.org. Crust photos credit: Linda and Dr. Dick Buscher, Live  Science "The Mysterious World of Cryptobiotic Soil."]

 

 

A Reverence for Rivers (1)

 

From the New York Times:

Los Angeles

Brown Warns of Drought Disaster; Says ‘Hard Choices’ Face California

Gov. Edmund G. Brown Jr. warned here today that drought-stricken California was “facing a disaster of immeasurable magnitude.”

“The specter of drought has been gathering momentum, not only in California but across the country,” the Democratic Governor declared, adding that people must learn that “this is an era of limits and there are some very hard choices to be made.”

 

Well, yes indeed, but the limits have proved difficult to respect, and the right choices challenging to make – that was a report from March 1977. In January 2014, not far off forty years later, Governor Jerry Brown reprised his earlier role and declared a state of emergency:

We can’t make it rain, but we can be much better prepared for the terrible consequences that California’s drought now threatens, including dramatically less water for our farms and communities and increased fires in both urban and rural areas. I’ve declared this emergency and I’m calling all Californians to conserve water in every way possible.

Given the historic (and largely unpredictable) nature of Californian aridity, it’s inevitable that, if you are a sufficient glutton for punishment to become governor twice, you will experience a couple of droughts. Unfortunately, Jerry Brown has been in charge for two of the worst – indeed, the current drought has broken essentially every historical record. But it is interesting to contemplate how, given the recognition of limits and hard choices forty years ago, we couldn’t be “much better prepared” today.

The 1977 news report was covering a two-day “Governor’s Drought Conference attended by about 800 water district officials, farmers, ranchers and other interested persons,” among the last category being the keynote speaker, Luna Leopold. The son of the influential conservationist and author, Aldo Leopold, author of A Sand County Almanac and Sketches Here and There, Luna became one of the world’s leading hydrologists during the latter half of the last century. He revolutionised and quantified for the first time the science of fluvial geomorphology and changed the way we think about rivers, how they and their landscapes work, and their role in the grand scheme of things – “Water is the most critical resource issue of our lifetime and our children’s lifetime. The health of our waters is the principal measure of how we live on the land.” He was, incidentally, also a close friend of, and collaborator with, my hero, Ralph Bagnold – I have a recording of the address he gave at Bagnold’s memorial service, his words made all the more compelling by the deep resonance of his voice.

But, back to the Los Angeles Convention Center in March 1977. You can’t help but be impressed that Brown invited Leopold to give the keynote address, but it seems likely that the governor and the ranchers were somewhat bemused to be told, in the speaker’s first, undoubtedly resonant, words, about Herodotus. 

Leopold titled his address A Reverence for Rivers. The full text is available online, but I shall extract from it here because I – and I hope that I’m not alone - find it not only provocative but as relevant today as it was nearly forty years ago. It’s stimulating food for thought – and a few posts.

Here are his opening words:

In the years around 450 B.C., that is about 2,400 years ago, the most widely travelled of the time was Herodotus. His book The Persian Wars differs from any previous written history in that he was conscious of the influences of geography, climate, and social custom in the direction of development of political and economic history of a state.
In all the intervening time, we seem not to have learned how the political and economic aspects of our lives are related to geography and climate, nor have we been able to bend social custom to accept the constraints placed on us by geography and climate.

“In all the intervening time” since 1977, we don’t seem to have learned a great deal either.

He goes on discuss our approach to renewable and non-renewable resources and comments that “it can hardly be called management”:

The management of resources cannot be carried out successfully if it is looked upon as just another facet of economics, administration, and politics. Yet the latter view describes rather accurately our present approach to resource use (it can hardly
be called management).

Being the scientist that he was, he asserts that “renewable resources”

... are parts of operating natural systems that can be deranged with very troublesome results. The hydrologic system of precipitation, streamflow, sediment, dissolved salts, ground water and evapotranspiration is typical of a system that can be deranged. Moreover, such operating systems are subject to natural fluctuations resulting from climate and geography. These fluctuations can be lessened but not eliminated.

I love that wording – the troublesome results from deranging natural operating systems. He goes on to acknowledge to his drought-stricken California audience that “none of us knows how to put into operation a philosophy of water management,” but suggests that a crisis offers some advantages in attracting attention to a problem and that “there may be some merit in examining some of the elements that might be included in such a philosophy.”

He recognised that his audience might not be instinctively sympathetic to “philosophic points of view” and proceeded to counter three possible “contrary arguments”:

(1) Our technology can fix it; (2) It is politically impossible; and (3) It is an example of the impractical idealism of crackpot environmentalists.

I will return to Leopold’s discussion of the first two, but his response to number three is a potent summary of his own philosophy and something that resonates today – at least with me:

… there is a balance or harmony in natural systems which, dictated by the laws of physics, has gradually developed during the 4 billion years of Earth's history. The maintenance of this balance is not only to the advantage of human organization,
but should be the object of both our wonder and our admiration. The desire to preserve this harmony must also be incorporated into any philosophy of water management, and I will call this, as did Herodotus, a reverence for rivers. If this is environmental idealism, then let it be said that I am an idealist.

So where, exactly, does Herodotus fit in to all this? Quite how Luna Leopold’s audience responded is lost in the mists of time, but he described how

Speaking of the Persians who dominated Asia Minor in the 5th century B.C., Herodotus said, "They never defile a river with the secretions of their bodies, nor even wash their hands in one; nor will they allow others to do so, as they have a great reverence for rivers." It is the last phrase that deserves our attention. The river is like an organism; it is internally self-adjusting. It is also resilient and can absorb changes imposed upon it, but not without limit.

So, having cast a somewhat different light on Brown's "era of limits," he concluded that

Man's engineering capabilities are nearly limitless. Our economic views are too insensitive to be the only criteria for judging the health of the river organism. What is needed is a gentler basis for perceiving the effects of our engineering capabilities. This more humble view of our relation to the hydrologic system requires a modicum of reverence for rivers.

Given the derangement of our planet’s river and sediment systems that we have accomplished, before and after 1977, you have to wonder whether we – now stuck in the Anthropocene – have any reverence at all. But I believe that, for whatever difference it might possibly make, it’s still worth listening to Luna Leopold.

To be continued…

[Image at the head of the post Lucy Nicholson/Reuter/Baltimore Sun, caption: "Discarded shopping carts lie   in the dry Tule river bed in Porterville, California October 14, 2014. In one of the towns hardest hit by California’s drought, the only way some residents can get water to flush the toilet is to drive to the fire station, hand-pump water into barrels and take it back home. The state’s three-year drought comes into   sharp focus in Tulare County, the dairy and citrus heart of the state’s vast agricultural belt, where more than 500 wells have dried up."

Image above, Kelly M. Grow/California Department of Water Resources: The South Fork of the Feather River feeding Lake Oroville on Sept. 5, 2014.]

 

The Missing Sink: Carbon storage in the world’s deserts

Deep-rooted and completely erroneous preconceptions of our planet’s arid lands as sterile bit-players in the great game of the earth’s dynamic systems have long inhibited our scientific enthusiasm for, and understanding of, the desert. We are now beginning to catch up – take, for example, this recent headline from the American Geophysical Union:

The world's deserts may be storing some of the climate-changing carbon dioxide emitted by human activities, a new study suggests. Massive aquifers underneath deserts could hold more carbon than all the plants on land, according to the new research.

As described in a summary of this research on Science Daily:

Humans add carbon dioxide to the atmosphere through fossil fuel combustion and deforestation. About 40 percent of this carbon stays in the atmosphere and roughly 30 percent enters the ocean, according to the University Corporation for Atmospheric Research. Scientists thought the remaining carbon was taken up by plants on land, but measurements show plants don't absorb all of the leftover carbon. Scientists have been searching for a place on land where the additional carbon is being stored--the so-called "missing carbon sink."

The lead author of the report in the AGU publication, Geophysical Research Letters, is Yan Li, a desert biogeochemist with the Chinese Academy of Sciences in Urumqi, Xinjiang; he and his team examined the character of groundwaters in the gigantic closed system of the arid Tarim Basin, and came up with some fascinating – and provocative – results. Runoff waters from the surrounding mountains pick up, as a normal part of the carbon cycle, some CO₂ dissolved from the rocks and soils through which the rivers flow. However, by the time that water ends up in aquifers, the underground reservoirs beneath the desert, it contains substantial amounts of DIC, dissolved inorganic carbon.

Being able to date the carbon, Li and his colleagues could distinguish between old carbon originating from the rivers and very young carbon added to the water as it seeped through the soils of the irrigated oases along the desert margins. These are poor soils, not in themselves sources of much CO₂ - it originates from the respiration of the roots of crops and microbes in the soil. And because these crops are irrigated almost constantly, not only to keep them growing but to wash out the salts that, as in all desert agriculture, accumulate in the soil, most of the CO₂ is transported downward into the groundwater moving out below the desert to be trapped in the deep aquifers. Importantly, because of the salts, these waters are saline and alkaline and the solubility of CO₂ in saline/alkaline water is much higher than in pure or acidic water – the desert groundwater is a very significant CO₂ sink. 

Because of their ability to date the carbon dissolved in the waters, the researchers were able to establish that the levels jumped substantially in historical times as the development of the Silk Road enabled the beginnings of oasis agriculture. Man’s activities – irrigation and over-irrigation – have augmented the efficiency of this carbon sink by, it is estimated, a factor of twelve:

Based on the various rates that carbon entered the desert throughout history, the study's authors estimate 20 billion metric tons (22 billion U.S. tons) of carbon is stored underneath the Tarim Basin desert, dissolved in an aquifer that contains roughly 10 times the amount of water held in the North American Great Lakes.

The study's authors approximate the world's desert aquifers contain roughly 1 trillion metric tons (1 trillion U.S. tons) of carbon--about a quarter more than the amount stored in living plants on land.

And because this is a saline and alkaline aquifer, the water is completely unsuitable for agriculture – it will likely remain below the desert as essentially permanent carbon storage - undoubtedly not the only missing sink, but a hitherto unidentified one. As Li remarks: “The fact that such a huge carbon pool and active sink has been unstudied for so long may simply be because it is remote and hidden under deserts: out of sight, out of mind.”

 

[Image at the head of this post is of agriculture and dunes along the northern edge of the Tarim Basin, Google Earth; diagram of the process of carbon storage from Yan Li, Yu-Gang Wang, R. A. Houghton, Li-Song Tang. Hidden carbon sink beneath desert. Geophysical Research Letters, 2015; DOI:10.1002/2015GL064222]