Archive for August, 2006

Mississippi meanders

Published by Garry Peterson on August 31, 2006 in Ecological Management, General, New Orleans and Reorganization. 0 Comments

NASA’s Earth Observation newsroom presents satelite images to go with the geological map of Mississippi Meanders used to make the top image of this blog.

NASA EOS image

NASA explains:

As it winds from Minnesota to the Gulf of Mexico, the Mississippi River is in constant flux. Fast water carries sediment while slow water deposits it. Soft riverbanks are continuously eroded. Floods occasionally spread across the wide, shallow valley that flanks the river, and new channels are left behind when the water recedes. This history of change is recorded in the Geological Investigation of the Alluvial Valley of the Lower Mississippi River, published by the Army Corps of Engineers in 1944.

This map of an area just north of the Atchafalaya River shows a slice of the complex history of the Mississippi. The modern river course is superimposed on channels from 1880 (green), 1820 (red), and 1765 (blue). Even earlier, prehistoric channels underlie the more recent patterns. An oxbow lake—a crescent of water left behind when a meander (bend in the river) closes itself off—remains from 1785. A satellite image from 1999 shows the current course of the river and the old oxbow lake. Despite modern human-made changes to the landscape, traces of the past remain, with roads and fields following the contours of past channels.

In the twentieth century, the rate of change on the Mississippi slowed. Levees now prevent the river from jumping its banks so often. The levees protect towns, farms, and roads near the banks of the river and maintain established shipping routes and ports in the Gulf of Mexico. The human engineering of the lower Mississippi has been so extensive that a natural migration of the Mississippi delta from its present location to the Atchafalaya River to the west was halted in the early 1960s by an Army Corps of Engineers project known as the Old River Control Structure (visible in the full-size Landsat image).

The delta switching has occurred every 1,000 years or so in the past. As sediment accumulates in the main channel, the elevation increases, and the channel becomes more shallow and meandering. Eventually the river finds a shorter, steeper descent to the Gulf. In the 1950s, engineers noticed that the river’s present channel was on the verge of shifting westward to the Atchafalaya River, which would have become the new route to the Gulf. Because of the industry and other development that depended on the present river course, the U.S. Congress authorized the construction of the Old River Control Structure to prevent the shift from happening.

For some related reading, John McPhee discusses the Old River Control Structure and US Army Corps attempts to regulate the Mississippi in his great 1989 book the Control of Nature. John Barry provides a history of the regulation of the Mississippi in his book Rising tide: the great Mississippi flood of 1927 and how it changed America.

I previously wrote about the ecology of the Mississippi, Michael Grunwald has an article in Grist Rotten to the Corps arguing that the Corps is behind New Orleans destruction, and wikipedia has an article about levee failures in New Orleans.

Low input agriculture as a tool for poverty alleviation

Published by Garry Peterson on August 29, 2006 in Ecological Economics, Ecological Management and General. 2 Comments
In many places around the world farmers are discovering that lower input (of fertilizers and pesticides) agriculture can be more profitable, and lower risk, than conventional high input alternatives.

Ethan Apri on NextBillion.net points to an  Asia Times article Turkey’s born-again farmer about Nazmi Ilicali, a farmer in Eastern Turkey who promotes organic agriculture to reduce rural poverty. The region grows organic wheat, rye, barley, white beans, green lentils, chickpeas and bulgur wheat and promotes itself and organizes sales via www.daphan.org. In the article Ilicali explains why and how he promotes organic agriculture:

He explains why, ironically, the poverty of this area makes it perfect for starting organic farming projects: “The earth in this area is especially suitable, because the local population is so poor that for years they have been unable to afford chemical fertilizers. The climate is good for organic agriculture, too. The frost and cold here even kill the eggs laid in the earth by insects, and because of that there is no need for pesticides - we have a totally chemical-free soil.”

Soon after joining the Daphan project, Nazmi took a further step. “After doing extensive research, I decided that organic agriculture was the only investment with good potential in the east of Turkey. But I also knew that any efforts would have to be made in an organized way. When I first became involved three years ago, I brought 633 farmers together, and the European Community gave me the financial support to set up the Eastern Anatolian Farmers and Livestock Keepers Union. Now we have 3,000 members, and are still gathering members like an avalanche gathers snow.”
…

Nazmi explains that when they first started, the biggest problem they had was the packaging and processing of their organic products. Rather than allowing this to stall their progress, they built a small factory and made every member of the association a shareholder. The factory began to grind their own cereals into flour and package it. Their brand identity, sales and profit margins have all improved since.

This experience is placed in a broader context by Bill McKibben. In April 2005 he had a good rich article The Cuba Diet, about Cuba’s semi-successful, involuntary transition to low-input organic agriculture in Harper’s magazine . To put Cuba’s unusual agricultural system (McKibben calls it something like high fedualism) in context he talks to Jules Pretty about other alternative agriculture systems around the world:

… strict organic agriculture isn’t what the Cubans practice (remember those pesticides for the potato bugs). “If you’re going to grow irrigated rice, you’ll almost always need some fertilizer,” said Jules Pretty, a professor at the University of Essex’s Department of Biological Sciences, who has looked at sustainable agriculture in fields around the world. “The problem is being judicious and careful.” It’s very clear, he added, “that Cuba is not an anomaly. All around the world small-scale successes are being scaled up to regional level.” Farmers in northeast Thailand, for instance, suffered when their rice markets disappeared in the Asian financial crisis of the late 1990s. “They’d borrowed money to invest in ‘modern agriculture,’ but they couldn’t get the price they needed. A movement emerged, farmers saying, ‘Maybe we should just concentrate on local markets, and not grow for Bangkok, not for other countries.’ They’ve started using a wide range of sustainability approaches—polyculture, tree crops and agroforestry, fish ponds. One hundred and fifty thousand farmers have made the shift in the last three years.”

Almost certainly, he said, such schemes are as productive as the monocultures they replaced. “Rice production goes down, but the production of all sorts of other things, like leafy vegetables, goes up.” And simply cutting way down on the costs of pesticides turns many bankrupt peasants solvent. “The farmer field schools began in Indonesia, with rice growers showing one another how to manage their paddies to look after beneficial insects,” just the kinds of predators the Cubans were growing in their low-tech labs. “There’s been a huge decrease in costs and not much of a change in yields.”

See also Elena Bennet’s Resilience Science post on Ecological synergisms in agriculture.

Complicated ecological tradeoffs from water & agriculture

Published by Garry Peterson on August 16, 2006 in Ecological Management and Greenlash. 0 Comments

A recent paper in Water Resources Research (2006: 42) by Eloise Kendy and John Bredehoeft Transient effects of groundwater pumping and surface-water-irrigation returns on streamflow shows how a long history of excess irrigation in the US west has prodcued streamflow that ecosystems and people have come to rely upon. Now improvements in irrigation effectiveness (i.e. more crop per drop) could reduce this streamflow. These connections show how complicated tradeoffs between different water uses can become. Fortunately, in this case, as in many others, it appears that more sophisticated water management can reduce the intensity of this tradeoff.

Abstract: In surface-water-irrigated western valleys, groundwater discharge from excess irrigation sustains winter streamflow at levels that exceed natural flows. This unnatural condition has persisted for so long that hydrologists, water managers, and water users consider it to be normal. Changing land uses and irrigation practices complicate efforts to manage groundwater discharge and, in turn, to protect instream flows. We examined the impacts on streamflow of (1) seasonal groundwater pumping at various distances from the Gallatin River and (2) improving irrigation efficiency in the Gallatin Valley, Montana. We show that the greater the distance from a seasonally pumping well to a stream, the less the stream depletion fluctuates seasonally and the greater the proportion of annual depletion occurs during the nonirrigation season. Furthermore, we show that increasing irrigation efficiency has implications beyond simply reducing diversions. Improving irrigation efficiency reduces fall and winter flows to a lower, but more natural condition than the artificially high conditions to which we have become accustomed. However, existing water users and aquatic ecosystems may rely upon return flows from inefficient irrigation systems. By strategically timing and locating artificial recharge within a basin, groundwater and surface water may be managed conjunctively to help maintain desirable streamflow conditions as land uses and irrigation practices change.

Eloise Kendy has a short related article in Geotimes (June 2005) Water woes: predictable but not inevitable, where she writes how land-use change produces inadvertent ecological engineering that should become more intentional and less haphazard.

The change from irrigated agriculture to residential development entails more than simply pumping groundwater. Most irrigation systems in the West — especially the oldest systems on the most productive ground — use diverted surface water. Irrigation water that crops do not use seeps into the soil and eventually reaches the water table, where it recharges groundwater in the underlying aquifer. So-called irrigation return flow is a major source of groundwater recharge in irrigated western valleys.

The irrigation-charged groundwater slowly makes its way underground to rivers, streams and springs, where it eventually discharges. Groundwater discharge from irrigation return flow keeps rivers flowing well into late summer and fall, even after all the snow has long since melted, even after the rains have stopped. Although not a natural phenomenon, we consider this annual flow pattern “normal,” for it has recurred for more than 30 years.

The most important hydrologic change brought on by urban and suburban development is a drastic reduction in groundwater recharge. Urban land surfaces such as roofs, roads and parking lots are impermeable. Rain and snowmelt run off these surfaces, instead of seeping into the ground and recharging aquifers. In a typical engineering design, runoff is quickly shunted into the nearest stream or river to rid the area of potential flood waters. Consequently, localized recharge greatly decreases, streamflow becomes “flashier” (larger fluctuations over shorter periods of time), and late-season, groundwater-fed streamflow decreases. When irrigation stops, seepage from excess irrigation water also stops, or continues to recharge the aquifer only from leaky ditches.

Almost without exception, rural residential development in the West relies on well water for domestic use. So, on top of reducing aquifer recharge, the change from surface-water-irrigated cropland to groundwater-irrigated yards increases aquifer discharge. Less water goes into the aquifer than before, and more water goes out.

Previously, irrigation diversions depleted streamflow in the spring and early summer, and irrigation return flow maintained streamflow well into the late summer and fall. Now, with fewer surface-water diversions, early flows increase, as does the risk of flooding. Conversely, late-season flows decrease, potentially leaving fish and downstream irrigators high and dry.

…

When sewers were put in place in Long Island, N.Y., in the 1950s, wastewater that previously recharged the aquifer now discharges straight into the ocean. The loss of aquifer recharge caused the water table to drop about 20 feet. To save the aquifer, more than 3,000 small recharge basins were constructed. Their average combined infiltration rate of 150 millions gallons per day has successfully reversed the trend of declining water levels in the aquifer.

Out West, many creative options exist for water management. Most of the basins within the Basin and Range province, which, loosely defined, extends from Canada to Mexico, provide ideal geologic settings for storing artificially recharged water underground. Using existing irrigation infrastructure, we could spread spring runoff onto benchlands, allowing it to flow underground toward rivers, where it would replace irrigation return flow as a resource for late-season use. Another simple option is to discourage landscaping that requires irrigation.

via Kevin Vranes’s No Se Nada.

Agricultural Patterns from NASA

Published by Garry Peterson on August 15, 2006 in General and Visualization. 0 Comments
From NASA’s Earth Observatory News an article on the diversity of Agricultural Patterns produced by farming. The images show the striking impacts of property rights and farming systems on land use patterns.

ag landscape patterns

via Navin on CSN

Using Tera Preta increase soil resilience

Published by Garry Peterson on August 11, 2006 in General, Reorganization and Tools. 2 Comments
A Nature News article Black is the new green (10 August 2006) explains research that aims to reinvent Terra Preta, anthropogenic highly productive charcoal rich soils, to improve soil for agriculture while sequestering carbon.
New ways of producing biofuels can to produce charcoal that can be used to enrich soil. This carbon is stored in the soil, and may be able to produce carbon negative fuels in a way that can boost agricultural productivity. From the Nature News article:

…[a group met at the] World Congress of Soil Science. Their agenda was to take terra preta from the annals of history and the backwaters of the Amazon into the twenty-first century world of carbon sequestration and biofuels.

They want to follow what the green revolution did for the developing world’s plants with a black revolution for the world’s soils. They are aware that this is a tough sell, not least because hardly anyone outside the room has heard of their product. But that does not dissuade them: more than one eye in the room had a distinctly evangelical gleam.

The soil scientists, archaeologists, geographers, agronomists, and anthropologists who study terra preta now agree that the Amazon’s dark earths, terra preta do índio, were made by the river basin’s original human residents, who were much more numerous than formerly supposed. The darkest patches correspond to the middens of settlements and are cluttered with crescents of broken pottery. The larger patches were once agricultural areas that the farmers enriched with charred trash of all sorts. Some soils are thought to be 7,000 years old. Compared with the surrounding soil, terra preta can contain three times as much phosphorus and nitrogen. And as its colour indicates, it contains far more carbon. In samples taken in Brazil by William Woods, an expert in abandoned settlements at the University of Kansas in Lawrence, the terra preta was up to 9% carbon, compared with 0.5% for plain soil from places nearby
…Take the work of Danny Day, the founder of Eprida. This “for-profit social-purpose enterprise” in Athens, Georgia, builds contraptions that farmers can use to turn farm waste into biofuel while making char. Farm waste (or a crop designed for biofuel use) is smouldered — pyrolysed, in the jargon — and this process gives off volatile organic molecules, which can be used as a basis for biodiesel or turned into hydrogen with the help of steam. After the pyrolysation, half of the starting material will be used up and half will be char. That can then be put back on the fields, where it will sequester carbon and help grow the next crop.

The remarkable thing about this process is that, even after the fuel has been burned, more carbon dioxide is removed from the atmosphere than is put back. Traditional biofuels claim to be ‘carbon neutral’, because the carbon dioxide assimilated by the growing biomass makes up for the carbon dioxide given off by the burning of the fuel. But as Lehmann points out, systems such as Day’s go one step further: “They are the only way to make a fuel that is actually carbon negative”.

Day’s pilot plant processes 10 to 25 kg of Georgia peanut hulls and pine pellets every hour. From 100 kg of biomass, the group gets 46 kg of carbon — half as char — and around 5 kg of hydrogen, enough to go 500 kilometres in a hydrogen-fuel-cell car (not that there are many around yet). Originally, Day was mostly interested in making biofuel; the char was just something he threw out, or used to make carbon filters. Then he discovered that his employees were reaping the culinary benefits of the enormous turnips that had sprung up on the piles of char lying around at the plant. Combining this char with ammonium bicarbonate, made using steam-recovered hydrogen, creates a soil additive that is now one of his process’s selling points; the ammonium bicarbonate is a nitrogen-based fertilizer.

update: WorldChanging has a bit more on the article