The Earth Story

Pac-Man farming and the disappearing Ogallala aquifer At first glance, this 2000 Landsat 7 image of Garden City in Kansas looks like an overly ambitious game of Pac-Man. But these rigid, circular patterns are actually crop fields, with tan circles representing harvested crops, and the red circles denoting healthy, irrigated crops. Central pivot irrigation created the Pac-Man motif of Garden City’s agriculture, and has transformed the local economy into America’s breadbasket powerhouse.

A drone based exploration of some landslides in Washington that have been triggered by water from irrigation

Lake Turkana: The next Aral Sea?

Africa's fourth largest lake is shared between Kenya and Ethiopia, occupying a basin in the Great African Rift where a new ocean may be in its early stages of formation. A haven of biodiversity on UNESCO's world heritage list (particularly for crocodiles and migrating birds) it is the only water in a barren and desertic landscape, making it a vital stopover point during avian migrations. The lake is 250km long, and 44 wide at its largest point, with an average depth of 30 metres.

Once known as Lake Rudolph, it has also been the discovery site of many early hominids, showing that the lake was an essential habitat (called by some the cradle of humankind) during our gradual evolution into modern humans. An island within the lake is an active volcano. Dating archaeological remains here is relatively easy, since the surrounding volcanoes have provided us with ash layers containing minerals such as zircon that can be dated using uranium lead isotopes. Ancient shorelines in the form of raised terraces rise up to 75 metres above the current level, reflecting wetter paleo climates when the lake was connected to the Nile (as evidenced by Nilotic species).

The lake also provides a major fishery resource on which many of the people living near its shores depend on for protein, most of the lake is in Kenya, though the main river that feeds it flows out of Ethiopia. The basin is endorheic, with no outflow rivers, and up until now the only form of water loss has been by evaporation, so the size and level fluctuate widely with the vagaries of climate.

A major new dam and irrigation project called Gibe3 on the river Omo is about to place the lake and its vital fisheries under long term threat, and a recent study by the University of Oxford worries that it might share the fate of the Aral sea, also once an important inland fishery that was killed by water diversion from the Amur and Syr Darya rivers to grow cotton in Soviet times. The study shows that water levels could drop by half, shrinking the lake drastically as a biosphere reserve and fishery (possibly even cutting it onto two smaller lakes) and stranding many lakeside communities in a newly made desert, as also happened in the Aral sea where famous photos of long stranded fishing fleets in ghost towns have become icons of how not to manage water resources.

There is a concomittant risk of political conflict over water rights, since the dam will be in Ethiopia while those who stand to lose the most are in Kenya. Similar tensions are running high elsewhere, for example over the damming of the Euphrates by Turkey. So far no environmental impact studies have been published, this research being the first to come out. Ethiopia claims the study's predictions are exaggerated and argues that all the surrounding countries stand to benefit from the cheap green electricity that the dam will generate.

The plans however belie this, since a vast sugar and biofuel farming area is due to be irrigated with the water (one scheme alone equalling the entire irrigated area of Kenya). Sugar is a very thirsty crop, like cotton, and growing it in the desert seems like a poor use of scarce water. Pastoralists are already being evicted by force from their lands to make way for these huge now agroprojects.

Loz

Image credit: Aocrane

http://www.theguardian.com/global-development/2014/mar/05/ethiopian-dam-gibe-iii-aral-sea-disaster http://whc.unesco.org/en/list/801 http://education.nationalgeographic.com/education/maps/geography-lake-turkana/?ar_a=1 Original paper, free access: http://www.africanstudies.ox.ac.uk/sites/sias/files/documents/WhatFutureLakeTurkana.pdf_ _

Ok, first note - you should not click on this video if you have a problem with rapidly moving images or flashing light. These video artists have taken satellite imagery across the US and combined the frames with extremely rapid shifts so that part of the frame always keeps the same shape but the surroundings flip rapidly from one spot to another. You can see how the geometric designs of civilization stay constant as the landscape shifts from spot to spot.

Water to the desert

This image was captured by the Earthkam camera on the International Space Station during a flight over Saudi Arabia earlier this year. The town of Wadi Aldwasir has an estimated population of about 70,000 inhabitants. It is in south-central Saudi Arabia, surrounded mostly by deserts. However, it sits in an ephemeral river channel – when it does rain, water flows through the gap in the hills at the southeast and enters the desert near the city. You can see salts visible in this photo sitting in that channel.

The presence of a river channel in a desert setting often leads to elevated groundwater levels. Groundwater will form in this setting when water flows in these channels – water will literally leak out of the bottom of the river and enter open porespace in the ground below.

Water leaking from a river will keep the level of groundwater fairly shallow, and shallow groundwater is in an area that humans can reach with drills and pumps. Each of the green circles in this image is a “Central pivot irrigation system” – an irrigation system pulls water from the ground at the center of the circle and the sprinkler assembly rotates around the center, watering the ground. Each of the green circles at this site is water being pulled from the ground and used to water crops.

Saudi Arabia is one of the heaviest consumers of groundwater in the world, but groundwater resources aren’t easily renewed, even here. It’s a desert; the river isn’t always flowing. Water that is pulled out of the ground can have been there for anything from months to millennia. In a desert like this, it likely will take a long time for water pumped from the ground to be replaced.

Satellite measurements have shown that Saudi Arabia has drawn down their groundwater supplies as fast as anywhere on Earth. Groundwater pumping is limited by energy costs – the deeper the water is, the more energy it takes to pump the water out of the ground. Saudi Arabia of course is a land of cheap energy, in this case supplied largely by the sun, so they’ve had the resource to get the water from the ground easily. But, the longer pumping goes on, the deeper groundwater gets and the more expensive it gets. Plus, deeper and older groundwater is often saltier and less useful for irrigation. Groundwater pumping can be used as a resource to grow crops, but eventually that resource will dry up.

In fact, if you look closely at this frame, there is a cluster of circles turning grey. These are likely irrigation systems that have been abandoned – either water wasn't shallow enough to run them or pumping the water became too expensive to manage those fields.

-JBB

Image credit: NASA/ISS http://images.earthkam.org/main.php?g2_itemId=799010 Read more: http://bit.ly/1IPEipg https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA20077_ _

Searching for something more valuable than oil.

This photo collage shows the Wadi As-Sirhan Basin in Saudi Arabia.

Saudia Arabia is renowned for its abundance of oil, but, over the last three decades they have been drilling in search of a resource far more precious: water.

Deep beneath the desert, farmers and engineers have tapped into groundwater supplies to help cultivate grains, fruits and vegetables.

These artificially coloured images taken in 1987, 1991, 2000 and 2012 demonstrate the evolution of agricultural practices in the region. Recently planted surfaces are in green, dry vegetation appearing in a brown/red hue, and areas of desert are shown in pink and yellow.

No one knows how much water lies under the desert; estimates vary from 250 to 867 cubic kilometres (50 to 208 cubic miles). Hydrologists have stated that, from an economic perspective, it will only be realistic to pump this resource for a period of fifty years.

-Jean

Image courtesy of NASA

The art of the Kalahari This image was taken by the Enhanced Thematic Mapper plus (ETM+) sensor on the Landsat 7 satellite. It shows a portion of the Kalahari Desert in Namibia. A large number of long, linear sand dunes are slowly migrating into this region, covering areas that used to be productive farmland. Basically every long, linear feature you see is a sand dune, and there is a single river channel towards the middle of the image. This is a false-color image, with the different colors showing different spectral properties. Vegetation appears red in the image. Near the center of the image, there is a lonely red dot of healthy vegetation; it is created by a farmer using central pivot irrigation, trying to keep crops growing despite the encroaching desert. This image was taken on August 14, 2000. -JBB Image credit: NASA/USGS landsat series http://archive.org/details/VE-IMG-16252

Future of Megadroughts in the American Southwest

The hand of man

This wonderful satellite photo highlights some of the ways in which we are modifying the surface and depths of the globe in order to keep our civilisation alive. The image was taken over a railyard in the Great Plains of Nebraska, and shows a bunch of trains laden with gleaming black coal to burn in power stations to produce electricity, emitting climate altering CO2 in the process and a semi circular irrigation pattern of a monoculture grain crop, sucking on some fast depleting aquifer (probably the Oglala) in order to keep us fed.

Power and food... satisfying these two needs for the 7 billion humans currently walking the Earth and desiring a comfortable lifestyle is putting the planet's systems under a strain that only major geological events such as asteroid strikes or the eruption of continent sized volcanic provinces ever managed to do before. We certainly live in unprecedented and interesting times.

Loz

Image credit: Digital Globe

Irrigation Boosts Rainfall

A new study published in the journal, Geophysical Research Letters, suggests that irrigation in California’s Central Valley boosts rainfall in the Colorado River basin. The study, by Jay Famiglietti of the University of California and Min-Hui Lo of the National Taiwan University, found that during the irrigation season, between May and October, evaporation doubles in the Central Valley.

They simulated climate over a 90-year period, and added in 350mm of irrigation water, from other published data, and found that this additional water lead to a 15 percent increase in rainfall in the Four Corners region and a 28 percent increase in runoff to the Colorado River.

---Adam

Image Credit: Aquafornia

References:

http://onlinelibrary.wiley.com/doi/10.1002/grl.50108/full

http://onlinelibrary.wiley.com/doi/10.1029/2010JD014775/abstract

http://www.sciencenews.org/view/generic/id/347691/description/Watering_fields_in_California_boosts_rainfall_in_Southwest

Pac-Man farming and the disappearing Ogallala aquifer

At first glance, this 2000 Landsat 7 image of Garden City in Kansas looks like an overly ambitious game of Pac-Man. But these rigid, circular patterns are actually crop fields, with tan circles representing harvested crops, and the red circles denoting healthy, irrigated crops. Central pivot irrigation created the Pac-Man motif of Garden City’s agriculture, and has transformed the local economy into America’s breadbasket powerhouse.

Garden City is in the middle of the High Plains, a region in the Midwest known for its dry summers and winters with less than 45 cm of rain a year. When central pivot irrigation was first developed, it shifted Garden City from its dependence on sporadic rainfall to groundwater from the Ogallala aquifer. Farming in the High Plains now relies fully on the Ogallala aquifer, one of the world’s largest groundwater sources that spans from Wyoming to Texas.

You’ve likely seen the equipment for central pivot irrigation before — a water pump that is extended down to an underground aquifer in the center of a crop field is connected to a wheeled pivot hooked up with sprinklers. The pivot slowly rotates around the field, spraying and irrigating the crops with fresh groundwater, creating the circular Pac-Man motif that is now synonymous with groundwater-dependent farming.

Despite once having enough water to cover all fifty American states by half a meter, the Ogallala aquifer is slowly running dry. Annually, about one-fifth of the crops in the United States are grown using fresh groundwater from the Ogallala aquifer, a volume of water equivalent to that of 18 Colorado Rivers. The semi-arid climate of the High Plains doesn’t supply sufficient rainfall to naturally recharge the aquifer, and in some counties, the water table has decreased by as much as half a meter in one year. Researchers estimate that agricultural production using water from the Ogallala aquifer will begin to decline after 2040, but if farmers could lower groundwater usage by just 20 percent, the decline will only begin after 2070.

But here is the real question — can the aquifer be sustained forever? Researchers estimate that it would take 6000 years for the aquifer to be naturally recharged. But for that to happen, farmers would immediately need to reduce their groundwater usage by 80 percent, which would dramatically lower crop production. That possibility is as realistic as beating the world record in a perfect game of Pac-Man — the Ogallala aquifer is an indispensable component of a $20-billion industry that exports crops and crop products to many parts of the world.

So the original question remains — how much more can the Ogallala aquifer be preserved as a finite resource? Many farmers are already preparing for that day of reckoning by growing crops don’t need irrigation and require less water. Other farmers are developing new methods that don’t depend on groundwater: instead of completely plowing fields after harvest, new crops are planted in the residual stems, which helps to lower soil erosion and moisture loss from the soil. Federal programs also offer incentives to farmers who help conserve grasslands — 25 million acres of which have been converted to crop fields since 1982 — that can be used to graze cattle and buffalo. But at the same time, subsidies for irrigation-dependent crops, such as corn, soybeans, and cotton, are higher than that for grassland conservation, with national and worldwide demand for irrigation-dependent crops remaining as high as ever.

So for many farmers, the choice to continue irrigating their crop fields with Ogallala groundwater is a straightforward one. However, the federal government and agricultural industry will eventually have to come to terms with the future of farming in the High Plains — farming using a water source that will not depend on the seemingly infinite Ogallala aquifer.

-DC

Photo credit: http://1.usa.gov/1G0qGFt More reading: http://1.usa.gov/1MtEF94 http://on.doi.gov/1Jszwjp

More on center pivot irrigation: http://bit.ly/1T1VSec http://bit.ly/1FCuutm More on the Ogallala aquifer: http://bit.ly/1Qxwedl http://wapo.st/1dk7QiD http://bit.ly/1Iq68dh

If you feel like trying against the world Pac-Man record: http://bit.ly/1eTY0VH

What is the deal with the Ogallala aquifer?

Located in the center of the United States is a region known as the high plains. It is comprised of portions of eight states and has a rough area of 450,000 km2. World renowned for its agricultural production, the region often touts the nickname the United States’ “breadbasket.” It contains about 5% of the country’s area, yet produces 30% of the nation’s agriculture and 40% of its beef. Looking at this landscape one hundred years ago, it would never be guessed that this region could not only produce that amount of food, but sustain that level of production for years.

The High Plains climate is one of low humidity, low to moderate precipitation, frequent winds and a high rate of evaporation. In other words, it was not suitable for intensive agriculture. Two droughts in the 1900s, spurred technological advancements in well drilling and groundwater pumping. From the 1950s to the 1970s groundwater withdrawal increased from 5 km3/year to 23km3/year. Depletion of one of the world’s largest aquifers had begun. (A km3 may be hard to visualize. It is the amount of water that covers 1 square kilometer of surface, 1 kilometer deep. It is an extremely large amount of water!)

An aquifer is not an underground river or an underground cave full of water. It is saturated sediment particles. A good analogy is a sponge. A wet sponge does not look like it is holding much water but once it is squeezed, its potential is revealed. The same is largely true for soils. They do not look like much but they can transmit and store a large amount of water. The Ogallala is not the technical name for this aquifer, whose real name is the High Plains aquifer. The Ogallala is one of the formations that make up the High Plains aquifer. The other two formations, the Brule and the Arikaree, are not as hydraulically conductive or large, which is why some refer to the aquifer as the Ogallala.

Water levels in this region have dropped precipitously over the past sixty years. Some places in Texas and Kansas have had water tables declines of fifty meters. If the amount of water entering the aquifer as recharge (rain, re-infiltrated irrigation water) is equal to the amount of water leaving the aquifer (irrigation, domestic use) water levels will stay constant. A water table drop of fifty meters indicates that recharge is minimal and groundwater withdrawals are exhausting the groundwater reserves.

The problem with managing the High Plains aquifer is that generalizations are tough to make. The aquifer is huge. It extends from Southern South Dakota to northern Texas. The eastern portion of the aquifer can receive over 50 cm more rain per year than areas in the west. On top of that, temperatures vary moving north to south, with temperature variations of 10-15°C common. Areas in the southwest region of the aquifer receive little rain and the rain that does fall is evaporated before it can enter the soil. Compare this to the northern portion of the aquifer, where water can infiltrate before it is evaporated and it is easy to see that climate has a huge effect on recharge rates. This may be part of the reason where the largest water table drops have been seen in Kansas and Nebraska.

Groundwater in arid regions is a vital resource. In some places it is the only source of drinking water for people. Agriculture uses an estimated 95% of the water that is withdrawn from the High Plains aquifer. It makes sense to curb and restrict the amount of water that can be withdrawn. Yet, so much of our food is produced in the region and thousands of livelihoods depend on the Ogallala. It is a complex situation that will be interesting to watch as groundwater levels continue to drop.

KKS

Reading about aquifer:

http://on.doi.gov/19MiFIc

http://on.doi.gov/1y3rgCh

http://bit.ly/1DrDJ4B

Photo courtesy of Texas A&M University

Wine a bit, you’ll feel better!

This is a photo of some vineyards in the midst of a desert in South Africa’s Northern Cape Province. It is a popular wine-making region near Augrabies Falls National Park, where the Orange River supplies accessible water to the surrounding area.

While you might think this area is not suitable for crops, carefully cultivated grapes can actually thrive in semi-arid conditions. Water requirements for wine production are low in comparison to other alcoholic beverages. It takes 240 litres of water, mainly for irrigation, to make one lovely cup of wine. Comparably it takes 500 litres of water to grow one pound of wheat.

So, in the interest of water conservation; drink wine, not beer!

-Jean

For wine enthusiasts: The area predominantly cultivates white grapes, but some red is also grown. The wine grape varieties grown here are Chenin Blanc, Colombard, Chardonnay, Pinotage, Shiraz, Cabernet Sauvignon, Merlot, Petit Verdot, Tannat, Muscadel (both red and white) and Muscat d'Alexandrie.

A breath of fresh air!

What do you think of this advertising campaign by Coca Cola in 2011?

What you're seeing is a “living” billboard located in the heart of Manila’s busiest street which handles an average of 316,345 cars a day.

The billboard is made of recycled coke bottles used as pots which are filled with a mixture of industrial by-products and organic fertilisers. The 3,600 pots were filled with Fukien tea plants and a drip irrigation system was installed for efficient watering.

This is a great example of how our concepts of advertising can evolve in an eco friendly manner. This campaign is both effective with regard coca cola’s advertising goals and is reflective of a growing public concern for the environment.

I would like to see much more of this in 2015.

-Jean

Aral Sea’s Eastern Lobe vanishes The Aral Sea was once a fairly large, inland, body of water on the border of what are today Uzbekistan and Kazakhstan. At its peak it was one of the largest lakes in the world. Its original outline is shown in black in this image. During the Soviet Era, much of the water from rivers that fed the enclosed lake was diverted for agriculture. Some of the areas nearby became world leaders in the production of cotton and other similar export goods, but that happened at the expense of the lake. The Aral Sea lost its main sources of water and shrank. The irrigation canals also weren’t built very reliably, so they leaked some of the water out as well. For decades now, the Aral Sea has been gradually drying out. Starting around the year 2000, the Aral Sea split into two separate lobes divided by a thin stretch of land. This year, for the first time, the easternmost of these lobes completely dried up. Sediments at the bottom of inland lakes aren’t pleasant things to have to deal with. Fertilizers from nearby agriculture flow downhill and accumulate at lake bottoms. Fine-grained sediments coated with fertilizers and other pollutants can be lifted up into the air by gentle winds, impacting the breathing of anyone downwind. The vanishing of this lake has also had impacts on the local climate as a major source of water and temperature stabilization has vanished. And on top of that, the more it shrinks, the worse all these problems become. The Aral Sea seems to be officially on its deathbed. -JBB Image credit: http://earthobservatory.nasa.gov/IOTD/view.php?id=84437&src=twitter-iotd Read more: http://www.fao.org/ag/magazine/9809/spot2.htm

CIRCULAR CROPS IN KANSAS Believe it or not this is not a painting, but an image captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on June 24, 2001. Variegated green crop circles cover what was once shortgrass prairie in Finney County, south-western Kansas USA; the most common crops in this region are corn, wheat and sorghum. The crops were each at a different point in development when the image was attained, which accounts for the varying shades of green and yellow. The healthy and growing crops are green. Corn grows into leafy stalks by late June while sorghum grows more slowly and would be smaller and therefore paler. Wheat is a bright gold as it is harvested in June, while the brown fields are those that have been recently harvested and ploughed under or are lying fallow for the year. These crops are partly fed by water from the Ogallala Aquifer, like many crops throughout large sections of the U.S. Midwest. The rivers and streams that fed the aquifer long ago have disappeared; water now takes a long time to travel through the soil to recharge the aquifer although the rates vary from region to region. The image shows centre-pivot irrigation systems that are 800 and 1,600 metres in diameter (0.5 and 1 mile), and the image covers an area of 37.2 x 38.8 km. -TEL http://www.nasa.gov/multimedia/imagegallery/image_feature_434.html Image credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.

Lake Turkana: The next Aral Sea? Africa's fourth largest lake is shared between Kenya and Ethiopia, occupying a basin in the Great African Rift where a new ocean may be in its early stages of formation. A haven of biodiversity on UNESCO's world heritage list (particularly for crocodiles and migrating birds) it is the only water in a barren and desertic landscape, making it a vital stopover point during avian migrations. The lake is 250km long, and 44 wide at its largest point, with an average depth of 30 metres.  Once known as Lake Rudolph, it has also been the discovery site of many early hominids, showing that the lake was an essential habitat (called by some the cradle of humankind) during our gradual evolution into modern humans. An island within the lake is an active volcano. Dating archaeological remains here is relatively easy, since the surrounding volcanoes have provided us with ash layers containing minerals such as zircon that can be dated using uranium lead isotopes. Ancient shorelines in the form of raised terraces rise up to 75 metres above the current level, reflecting wetter paleo climates when the lake was connected to the Nile (as evidenced by Nilotic species). The lake also provides a major fishery resource on which many of the people living near its shores depend on for protein, most of the lake is in Kenya, though the main river that feeds it flows out of Ethiopia. The basin is endorheic, with no outflow rivers, and up until now the only form of water loss has been by evaporation, so the size and level fluctuate widely with the vagaries of climate. A major new dam and irrigation project called Gibe3 on the river Omo is about to place the lake and its vital fisheries under long term threat, and a recent study by the University of Oxford worries that it might share the fate of the Aral sea, also once an important inland fishery that was killed by water diversion from the Amur and Syr Darya rivers to grow cotton in Soviet times. The study shows that water levels could drop by half, shrinking the lake drastically as a biosphere reserve and fishery (possibly even cutting it onto two smaller lakes) and stranding many lakeside communities in a newly made desert, as also happened in the Aral sea where famous photos of long stranded fishing fleets in ghost towns have become icons of how not to manage water resources. There is a concomittant risk of political conflict over water rights, since the dam will be in Ethiopia while those who stand to lose the most are in Kenya. Similar tensions are running high elsewhere, for example over the damming of the Euphrates by Turkey. So far no environmental impact studies have been published, this research being the first to come out. Ethiopia claims the study's predictions are exaggerated and argues that all the surrounding countries stand to benefit from the cheap green electricity that the dam will generate.  The plans however belie this, since a vast sugar and biofuel farming area is due to be irrigated with the water (one scheme alone equalling the entire irrigated area of Kenya). Sugar is a very thirsty crop, like cotton, and growing it in the desert seems like a poor use of scarce water. Pastoralists are already being evicted by force from their lands to make way for these huge now agroprojects. Loz Image credit: Aocrane  http://www.theguardian.com/global-development/2014/mar/05/ethiopian-dam-gibe-iii-aral-sea-disaster http://whc.unesco.org/en/list/801 http://education.nationalgeographic.com/education/maps/geography-lake-turkana/?ar_a=1 Original paper, free access:http://www.africanstudies.ox.ac.uk/sites/sias/files/documents/WhatFutureLakeTurkana.pdf