New Mexico's Acequias: Irrigation and Social Organization

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Social stability is the last but perhaps the most important of irrigation's "3s", for without adequate social organization and long term stability, irrigation is impossible. In the United States a variety of cooperative, local, state and federal agencies act to provide the necessary social organization for water management, with the Federal Bureau of Reclamation the best known and largest entity. That federal agency has been responsible for the development and maintenance of a series of huge projects in the western United States including the Colorado River projects, the Columbia Basin Project and parts of California's complicated water management system. All of those systems have venerable ancestries. Immense irrigation projects under centralized control were known to the ancient societies of Mesopotamia, while small and locally controlled irrigation projects date to long before the beginnings of recorded history in all arid and semi-arid parts of the world where agriculture has been practiced.

The state of New Mexico, one of the longest European settled parts of the United States, has a tradition of irrigated agriculture stretching back well before the first European contact. With parts of the Colorado River projects and large ones along the Rio Grande (Rio Bravo del Norte) New Mexico is something of a microcosm of virtually all of the types of irrigation water control known in the western United States. It also has some of the more complicated water laws, for it is a mostly arid state but also has high mountains where melting winter snows are the sources of exotic rivers, most notably the Rio Grande and its largest tributary the Pecos. Allocation of that water is a complicated task, a task made increasingly difficult by drought years when mountain show is scarce. In addition to dividing water between users who live within its boundaries, New Mexico is obligated to send water to downstream users on the Rio Grande, the Pecos and several smaller streams into Texas and Mexico (and in a less complicated set of relations to downstream users on the Colorado - New Mexican users of water destined for the Colorado are few in number).

Snow in New Mexico, 16 March 2005

source: NASA Earth Observatory

Acequias in New Mexico (with a few also in Colorado) are numerous, almost 1,000 of the gravity driven channels bring water from highland areas for use in towns and agricultural plots. They are also very old, brought to the area by settlers from Mexico and Spain who were familiar with community operated irrigation first in Spain and later in New Spain (Mexico). Some of the canals themselves may actually date to pre-contact groups, for acequias use an ancient technology widespread where snowmelt in nearby mountains allows agriculture on downhill sites. The social organization in pre-contact groups is for the most part unknown, and some of the current aspects of acequia management may have roots there, but the acequia associations are quite similar in character to much older ones in México and in Spain.

While ancien regime Spain and its colonies were not in the remotest sense of the term democratic in almost all aspects of governance, acequia associations were participatory democracy in its most pristine form. Yearly or more often those who had a share in the water delivered by an acequia met, a mayordomo (ditch boss) or leader was chosen, and both the allocation of water and of tasks necessary to keep the channels open, free of silt and debris, were made by common consent. A kind of corvée was in effect, for peasants were compelled to spend time working on the channels, but instead of working for benefit of the state or the nobility as in other corvée, they were working for the common good of their local community and for personal benefit.

The acequia associations of contemporary New Mexico share that characteristic of participatory democracy (no, New England town meetings are not the only example of direct democracy in the United States). For the past several decades the associations have become legal entities and an integral element in the management of water in New Mexico. Beneficiaries of the water are compelled to participate in the maintenance of the ditches, and in years of drought they must make the difficult decisions on how to allocate the scarce resource.

Folr a fascinating look at acequias and the experience of being a ditch boss in New Mexico, see Stanley Crawford's Mayordomo: Chronicle of an Acequia in Northern New Mexico.

Notes IV: Global Water Magazine

Washington Monument, Mt. Vernon Square, Baltimore, MD

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Material seems to be coming at me faster than I can pull it into some kind of coherence. I had planned next to put up a posting about acequias and the water laws of New Mexico, but this morning the estimable blog Waterwired pointed me toward a new online publication available free from the Global Water Program at Johns Hopkins University, Global Water Magazine. The Baltimore university is a suitable venue for the magazine. Its medical school is world famous, but the university also has strengths in many other areas related to water and water management. The first true research university in the United States, the first president of Johns Hopkins was the geographer Daniel Coit Gilman (who had earlier served as president of the University of California, my Ph.D. alma mater). Under the father and son Wolman, its Geography and Environmental Engineering program was one of the preeminent places in the United States for the study of physical geography and water related problems. More recently its Global Water Program has brought together scholars from a number of disciplines to study all kinds of issues related to water. The first issue of the magazine is engaging, and the publication promises to become an important intermediary between scientific research on water issues and the public. RECOMMENDED!

Notes III

Carhenge, Alliance, Nebraska

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In the posting about dams, I failed to note one major issue, the possibility of failure. Well-engineered dams rarely fail, but poor engineering, extreme weather events and lack of proper maintenance can lead to failures. In a few cases so can bad water management as illustrated by the first pages in Powell's Dead Pool, where the author describes what could have been a catastrophic failure of Glen Canyon Dam on the Colorado River.  Under the worst of circumstances, a catastrophic failure can lead to hundreds or even thousands of casualties. The most famous dam failure in the United States was at Johnstown, PA in 1889 when a badly maintained dam broke and killed 2,200 people. (That same benighted city had further floods in 1936 and again in 1977, devastating to property but not nearly as deadly for people, and neither was the consequence of a dam failure but rather of extreme weather.) Two days ago a small dam in Iowa collapsed after torrential rains. Knowing the failure was likely, deaths were apparently avoided, but several downstream towns had to be evacuated, and there was substantial property damage.

The St. Francis Dam, a water supply dam built in the early 1920s and designed by the famed California water engineer William  Mulholland, catastrophically failed on 12 March 1928 due to an engineering error. The ensuing flood killed 450 people and washed away towns and farms in the Santa Clarita Valley NW of Los Angeles.  Another badly engineered dam failure was the collapse of the irrigation retention  Teton Dam in Idaho in 1976 leading to 11 deaths and tremendous property damage downstream (see some pictures of the collapse on the website of a civil engineering faculty member at San Diego State University. Driving through the area later that summer, I stopped in Rexburg, Idaho to witness some of the devastation, but I have not scanned my slides as yet).

Shortly after posting the piece on glaciers yesterday, I read the New York Times (NYT) Sunday 25 July issue. While I am no fan of their regular columnist Thomas Friedmann,  he has an interesting op-ed  on global warming worth a read. This has been one of the hottest summers ever recorded in the eastern United States, and if current trends continue it could be the hottest yet recorded. Despite that heat (which it must be noted may be completely unrelated to climate change) the Senate has killed even the feeble climate legislation pending before it. Perhaps that is all to the well, for sometimes half measures like those in the bill now dead are worse than no action at all, but the lack of attention to the matter of climate change and the overuse of petroleum products in a hot summer with the Gulf oil gusher only temporarily capped is quite disturbing. It would seem those topics should be the subject of a national frenzy and demand for action. This morning's NYT has a good piece by their regular columnist and Nobel laureate Paul Krugman bemoaning the Senate's action, or or more exactly their lack of action placing a substantial share of the blame on the unprincipled ex-presidential candidate McCain and showing how the demands of the coal and petroleum oligopolies have trumped the public interest.

More water woes in the DC area. The drought may have broken for a time with heavy rains and strong winds accompanying a thunderstorm yesterday afternoon. The storm led to numerous electrical supply problems, and one facility loosing power was a major filtration facility of the Washington Suburban Sanitary Commission causing it to once again issue mandatory water usage limitations for Montgomery and Prince Georges Counties. While water supply systems are often discussed in the abstract and without reference to other elements of urban infrastructure, storms and other catastrophic events illustrate how interdependent those elements are.

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Climate Change - Glacial Retreat

Receding glacier, Upper Joffre Lake, British Columbia, Canada

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Any discussion of world water supplies over the next century must take into account climate change or what is frequently termed "global warming." The scientific consensus has long since concluded that an increase in global temperatures of several degrees over the next century is nearly certain. The only remaining debate is on how great and how fast the warming will be. That is an important debate, but a little outside our purview. What is important is the impact of increased temperatures on world water supplies. The worst case scenarios for that issue are, to use a very bad pun, chilling indeed.

One early sign of the increase in global temperatures is the recession of glacial ice in the Northern Hemisphere and of mountain glaciers in tropical areas. Glaciers are an important part of the water supply equation as well as a key variable in world climates. Glacial ice acts as a natural reservoir helping to keep runoff in streams constant over the year and from wet years to dry ones. Many perennial streams would run dry for several months a year, and for several years in succession in a severe drought, were it not for glacial melt. Exotic rivers in North America and Asia depend on glacial melt for a sizable part of their flow. The disappearing glaciers of the Rockies are major suppliers of water to the great American Rivers of the west. As a sad example, Glacier National Park is rapidly loosing its namesake features and may have no glacial ice in less than a century. In the Coast Range of British Columbia many glaciers are rapidly melting, like the one feeding Joffre Lakes, one of the most stunning sets of glacial lakes in the world. Not long ago that glacier reached the water of the upper lake. Now the melting glacier is more than 100 meters higher than the lake surface.

Highland glaciers are found in several tropical areas where there is clear evidence of rapid melting. Much of highland tropical South America, including populated parts of Ecuador, Peru, and Bolivia, has permanent streams only because of the water released when glaciers in the high mountains melt. Urban water supplies and irrigation are dependent on that water, for the region is characterized by a division between a wet season and a dry season. There is disturbing evidence of glacial retreat in that area as there is in New Guinea. Kilimanjaro has one of the few glaciers in Africa, and the debate is not if the glacier will disappear but when with the best guess being in about 10 years.

Outside the tropics there is rapid glacial melting in the Himalaya. An unfortunate error in a major climate report concerning glacial melting in the Himalayas has been used as "evidence" by those opposed to the idea of global warming, persons who believe, against all evidence, that global warming is a myth being perpetrated by greedy scientists to get more research funding. The elected Attorney General of the antediluvian Commonwealth of ole Virginny is among those anti-scientific Luddites. Almost all of them are slavishly repeating the propaganda generated by the coal and petroleum industry, an industry which does not want to have any limits placed on coal and oil consumption, the major source of the most important greenhouse gas carbon dioxide. It is clear the glaciers are less important as sources of water in major Asian rivers than the report indicated, and the rate of melting is slower than the alarmist information in the report. But glacial melt in the world's highest mountains is crucial to the flow of the Indus and significant in several other streams. The retreat of those glaciers portends catastrophe in an area where water supplies are already seen as inadequate to meet increasing demands.

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Irrigation and Salt

Wind eroded and salt encrusted hoodoos, Atacama Desert, Chile

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For the past several days I have been wracking my memory and rifling my notes to find the first time I encountered the "3 s" of irrigation - silt, salt and [political] stability. The idea is so straightforward that perhaps the term has been around forever, or at least as long as supplemental water has been used to grow crops. Salt and silt threaten the utility of irrigation works and the soils to which water is applied, while political stability is required if irrigation works are to be maintained over time. Irrigation at any significant scale is a cooperative activity requiring many people to participate in the construction and upkeep of the impoundments to store water, the canals to bring it to fields, and the drains to remove excess water and prevent water-logging of soils. Archaeology and history provide numerous examples of cases where irrigation systems fell into disrepair because soils became too saline for use, because impoundments and canals were clogged with silt, or because political unrest made it impossible to maintain the irrigation works. On occasion the destruction of irrigation works has been a deliberate ploy in warfare as an enemy attempts to starve a population by destroying its agriculture.

Silting behind large dams was noted in the posting on immense dams. It is also a problem behind even the smallest hydraulic barriers and unless water is moving rapidly, it can be a problem in canals as well. In a later posting we shall examine that idea in a bit more detail. In later postings and in the lectures we shall also examine the importance of political stability in the maintenance of irrigation systems.

Today I would like to make a few comments about salt as an enemy of irrigation projects. Salinization is a complex problem for all water systems. Many mineral salts, including the most important single one NaCl or sodium chloride (common table salt), dissolve readily in water. At low concentrations those salts can be be inconsequential or even beneficial for human consumption and agricultural use. At some level of concentration, however, they become a problem, and beyond some maximum concentration the water is no longer useful. We may look at salts other than NaCl later, but for today let us limit discussion to it.

Crop plants vary greatly in tolerance to saline soils and salty water. Grains and grasses tend to be more tolerant than other field crops, while most tree crops are intolerant of saline conditions. When land is being considered for irrigation, an early test is of the natural salinity of the soil recognizing that high value fruit, vegetable, fiber and tree crops are unlikely to thrive if the soil is already quite saline. Grain crops in general do not return enough value per hectare to justify investment in irrigation facilities.

Salts accumulate in soils through a variety of processes, and some soils are naturally saline, especially ones derived from rock substrates containing high levels of salt. Elsewhere in arid areas evaporation of surface ponds and lakes leads to pockets of salty soil (often called playas in Mexico and the southwestern US  and salinas in South America). Once overlain by glaciers, with numerous small ponds and lakes left as the glaciers receded the now semi-arid southern part of the Canadian province of Alberta, its agricultural area, has salty soils spread quite widely. Some of those soils derive from salty substrates, while other areas were once covered by waters now evaporated away. As grains and grass fed livestock are the primary agricultural products, the presence of salty soil is not a great hindrance to agriculture in Alberta (uncolored areas on the map are generally unsuitable for agriculture for other reasons, while blue areas are lakes and streams).

Source: Agriculture Canada and Province of Alberta

Commonly soils become salty after irrigation commences. Not infrequently in arid areas the water used for irrigation is itself  saline. Rainwater dissolves salt as it flows across desert landscapes in infrequent storms. Water captured in impoundments becomes increasingly saline as evaporation occurs. The extremely high rate of evaporation in hot desert areas like those of the southwestern US mean that water leaving Lake Powell or Lake Mead is far saltier than water flowing into those reservoirs. Applied to the soil in areas with high rates of evaporation, some salt from that water is added to the soil with irrigation. Much of the salt is leached to lower levels in the soil profile, and some of that, in turn, is washed away. But water retained in the soil can be  returned to the surface in a capillary process as water is drawn upwards to the soil surface by evaporation.

Rain or irrigation, in the absence of leaching, can bring salts to the surface by capillary action

Source: Wikipedia Media Commons

Only if it is possible to flush the salts by using a large quantity of water to redissolve the salts and thus to remove them can the eventual salinization of the soils be prevented. Accumulation of salt in soils has rendered substantial areas once productive agricultural zones into salty desert too saline for crops. In the Middle East and in arid parts of Asia, many square kilometers of once productive agricultural activity have been abandoned because of salinization. 

Source: Australia Department of Agriculture, Fisheries and Forestry, Bureau of Rural Sciences

While irrigation agriculture is fairly new to Australia, the Murray River Basin in the southeastern quadrant has been irrigated for more than a century. Not surprisingly, that arid area is reporting salinity problems as the map illustrates.

Dams - The Fascination of the Immense

Three Gorges Dam and Reservoir, Yangtze River, China, June 2009

NASA Earth Observatory

Standing on the Nevada shore (being careful not to cross over into Arizona where one might be arrested as an enemy alien) and admiring the sleek arch and art deco works of the great Boulder Dam (aka Hoover Dam) across the Colorado it is difficult not to be awed at the power of humanity. Many years ago a famous architect working on one of the megalomaniac urban design projects for which his field is notorious said something to the effect "make no little plans for they have no power to stir men's blood."  The design project thankfully came to naught, but his statement still has power. Nowhere is that more true than in the construction of huge dams. The icons of the New Deal in the United States are large dams, from the impressive structures on the Tennessee River and its tributaries as a part of the TVA to the grandest two of all, Boulder Dam on the Colorado and Grand Coulée on the Columbia. Subsequently dictators, autocrats, and even a few leaders in nominally democratic states have ordered construction of immense dams including ones on most of Russia's great rivers, on the Nile, on the Paraná, and on China's Yangtze. The dams have been variously designed to prevent flooding, to improve navigation, to store water for irrigation, and to produce electricity, with most of them intended to do at least two of that magic four.

Immense dams have come with a set of problems, however. Blocking the normal flow of the river, they serve also to block the flow of silt, and it collects behind the dams. The Aswan Dams on the Nile have blocked the flow of silt onto Egypt's riverine fields. While they generate a huge amount of electricity, much of that is used to produce fertilizer to take the place of the silt that once made the Nile Valley a breadbasket. Meanwhile the Nile delta is rapidly receding (and Egypt is getting smaller) as it is not receiving silt from upstream. The huge dams on the Colorado in the United States are also rapidly silting, though the low flows of the past decade mean that silting has been slowed. Eventually silting will render the dams useless for water storage and degrade or eliminate their benefits of flood control, navigation, irrigation water storage, and hydroelectric production. All dams are subject to silting, but the problem is especially great on rivers like the Colorado and the Nile whose headwaters include areas of easily eroded materials like sandstone.

A motto of the early Soviet experiment was "socialism plus electricity equals communism," and the construction of immense hydroelectric dams was a key goal throughout the ill-fated Leninist-Stalinist pseudo socialist experiment. A year ago Sayano–Shushenskaya Dam, one of the huge dams in Russia built by the Soviets to produce electricity, experienced a large explosion in its powerhouse, flooding the powerhouse and among other things sending a plume of lubricant oil down the Yenisei toward the Arctic, destroying several turbines, and killing at least 74 people. For a time Russia's electricity supply was reduced by a sizable percentage, and several key export industries, including aluminum production, were harmed. The flooded powerhouse had ot be closed and repaired, a process still ongoing, though the dam is again producing electricity.

Yesterday evening BBC News America had a story on flooding in China, high water on the Yangtze below the world's largest dam. One of the functions of the dam was to prevent downstream flooding, but it would seem it is having almost the opposite result. At least according to Chinese authorities the dam itself, also intended to  is secure  Earlier it was discovered that large dams in China were creating earthquakes and might have been directly responsible for several large and deadly temblors.

One must hope the Three Gorges Dam is the final immense dam built on earth to improve navigation on the Yangtze, to store water for downstream irrigation, and to produce hydroelectricity. Given the predilictions of totalitarian governments that may be a vain hope, but accumulated evidence makes it clear that huge dams create problems far greater than those they are intended to resolve.

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Water and Agriculture: A General Overview

Boh Tea Plantation, Cameron Highlands, Malaysia

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Agriculture is by a considerable measure the largest single human use of water. Leaving animal husbandry aside for the moment, some of the water used by crop plants is taken up directly from soil moisture created by precipitation in what is often called rain fed agriculture. It has become conventional to call that water from precipitation green water (a somewhat unfortunate usage, for the term is also applied to water seriously contaminated with algae). In the humid zone countries of the northern Hemisphere, including the eastern parts of the United States, green water allows a variety of crops to be grown without supplemental irrigation, and precipitation supplies all of the water for the crop plants. Such is the case in the tea growing area in the tropical highlands of Malaysia where tea is but one of a variety of crops grown dependent on the ample rainfall.

Elsewhere agriculture as presently practiced requires the addition of water beyond that provided by precipitation. Water obtained from streams, lakes and underground aquifers is usually termed blue water (again an unfortunate usage, for blue water has a quite different meaning to sailors). In sub-humid zones  irrigation may provide only small amounts of additional water applied at specific times during the growing season. In truly arid areas little or no crop production is possible without continual irrigation throughout the growing season. An area like the Salt River Valley of Arizona would not be useful for agriculture if not for irrigation.  Many other areas in the western United States can be used for water dependent crops only because of irrigation. Without irrigation in those areas, rain-fed agriculture could only produce grains Like wheat and barley.

The map below illustrates blue water withdrawals from various sources like lakes and reservoirs and underground aquifers for agriculture. It illustrates the great importance of supplemental water in tropical and subtropical areas, particularly in the Middle East and Asia. A very large fraction of the world's population depends on food grown with at least some use of blue water in irrigation, including most of the populations of India and China. The data are averages for usage in whole countries from the Food and Agriculture Organization (FAO), a Rome based unit of the United Nations.

Not all water used in agriculture is consumed, that is lost to evapo-transpiration or incorporated in the crop, but a great deal is. The map below composed from remote sensing imagery at the Institut für Physische Geographie (Physical Geographical Institute) of the Johann Wolfgang Goethe University of Frankfurt am Main in Germany shows the consumptive use of blue water by agriculture across the globe. The map is part of a very large project on world irrigation at the institute. 

Notes II

Sheep Lake, Steens Mountain, Oregon 2004

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Yesterday BP Oil announced that the unrestrained flow of oil from the blowout in the Gulf of Mexico has been stopped, at least for awhile, marking what we must hope is close to the end of one of the worst crimes against man and nature ever committed by an almost unrestrained oligopoly. I have to admit skepticism that the spillage has indeed ended, but even if it has, the deleterious effects on the ecology of the Gulf (and on public health) of the vast quantity of oil spilled into the Gulf will be a problem for decades, probably for generations. Meanwhile drilling for natural gas in the Marcellus shale continues, and the prospects of fouling a major watershed, a supplier of drinking water to multiple millions of users on the Atlantic Coast, continue unabated.

The Virginia Department of Environmental Quality issued a drought watch on 14 July 2010. In northern Virginia thunderstorms brought heavy rain  (and damaging wind) over the past week, but there is still a precipitation deficit for the current water year. An exceptionally dry final part of summer could create problems for agriculture and for urban water supplies depending on run of river flows rather than storage dams. At the moment the problem in Virginia is most severe in the area usually called Southside (from Virginia Beach westward following the North Carolina border).The drought watch extends into parts of all the adjacent states. Darker brown shades indicate higher levels of water deficiency on the USGS map below which was posted 15 July (maps are posted weekly at the website Water Watch, a valuable resource).

The Occoquan Watershed

George Mason University Campus Fountain, July 2010

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This morning I was looking for some local materials to include in the water course, and I chanced upon a good (if too small a scale) land-use map for the Occoquan Watershed (I hope to find a similar map at a bigger scale for use in a Power Point). Our Fairfax City house sits just slightly to the Potomac watershed (small streams draining directly into the river) side of the interfluve dividing the watersheds of the Potomac and the Occoquan. The GMU campus sits on the interfluve,and a part of the campus is on the opposite slope with water draining into small streams feeding the Occoquan (which itself eventually, just southeast of its eponymous town, flows into the Potomac).

Bull Run, one of the Occoquan's tributaries is very famous, for its small valley at the edge of Manassas City was the site of two of the more vicious battles of the Civil War. At the time of the Civil War and until quite recently the almost 1550 square kilometer basin of the Occoquan was predominantly rural with farmlands, wooded areas and only a few small towns and the small city of Manassas. Since the 1970s and especially since 1990 the watershed has  been rapidly urbanized with farm fields and pastures converted to townhouse projects and small "estates" along with the usual fast food and strip mall development. That has radically changed the timing and the quality of water run off into the Occoquan, for now much of the watershed is paved and impermeable even as urban uses add contaminants to the water flowing toward the river..

Prior to much urbanization the river became an important drinking water source supplying much of the urban water in Prince William County (including Manassas and Manassas Park cities) and some of the water consumed in Fairfax County, the two largest counties by population in Virginia. Altogether nearly 1,200,000 people are connected to water supply systems which use some Occoquan river water. A substantial dam impounds a tributary of the river and creates Lake Manassas, a water supply reservoir for its namesake city. Downstream another dam impounds the Occoquan Reservoir supplying much of Prince William County and large parts of adjacent Fairfax County. While other sources of water are used by both counties, the Occoquan could in an emergency supply most users. A bit further downstream yet near the town of Occoquan is one of the largest sewage treatment facilities in the Washington, DC metropolitan area, sending treated water into the Occoquan just before that river joins the Potomac.

A crucial element in the urban water supply of Washington, DC's Virginia slurbs, the Occoquan is also a major recreation resource for the area, and the undeveloped lands along its banks provide a substantial amount of open space. Unfortunately the stream is badly polluted in places, and runoff from developed areas makes it an endangered stream. The Prince William Conservation Alliance has an excellent webpage examining the issues of pollution in the Occoquan basin. The quality of water in the river is important for those of us condemned to live in Northern Virginia!

Watershed Map from Prince William Conservation Alliance.

Notes

Windmill, Pacific Ocean near Todos Santos, BCS, Mexico 2009

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Occasionally I shall post some random notes about issues, comments that do not fit together coherently. This is the first such posting.

This morning I was looking for some materials on local water concerns to use with the course, and I learned of a problem which was new to me. Fairfax City includes within its boundaries a sizable tank farm, a gasoline and diesel fuel depot. In 1992 there was a large underground spill that sent gasoline and other petroleum derivatives in a plume far downstream into the Mantua area of Fairfax County. That leakage cost a huge amount of money spent to clean up impacts in a scenic and generally uparket residential area. I had not paid attention to a much smaller leakage found in late 2009 which has not yet been fully cleaned up. The leak is fairly small, but it marks yet another insult to the land and waters of the Potomac Basin.

Several weeks ago I read reviews of James Lawrence Powell's Dead Pool (Berkeley: University of California Press, 2008, ISBN 978-0-520-25477-0), a  history and analysis of the dams on the lower Colorado especially Glen Canyon and Boulder Dams. The reviews were correct, for it is one of the most important books on water issues in the United States published in the past decade and should be required reading for almost everyone concerned with water supply in an era of population growth and climate change. The first few pages describing what might have happened if Glen Canyon Dam had failed in 1983 make for harrowing reading. The remainder of the book examines how the dams have shaped life in the southwestern corner of the continental US (and in adjacent parts of México) and what may happen as rainfall decreases due to climate change, reading almost as harrowing as the first few pages.

Drought II -- A Drought in the Washington, DC Area?

Last week it was confirmed that the June just ended was the hottest and nearly the driest recorded in the eastern states of the United States. Thus far this year there is a rainfall deficit in the Washington, DC area. Farmers in nearby area of Pennsylvania, Maryland, Virginia and West Virginia are beginning to worry about their crops. The  lack of rainfall is a problem even when temperatures are normal as there is little use of irrigation in the normally humid region. [Just as I started writing this posting, heavy rain associated with a thunderstorm started to fall.]

Should the lower rainfall amounts continue through the summer, there could be problems of urban water supply in Washington, DC and its surroundings. Unlike most American cities of comparable size, Washington does not have large storage reservoirs to augment low flows during droughts, reservoirs filled in seasons and years of normal or above normal rainfall. Instead Washington depends on run of river flows on the Potomac River, its major water source. The Potomac and tributaries are the source for almost all of the water consumed in Washington, DC and its Virginia suburbs. Part of the demand in the Maryland suburban counties is met from the Patuxent, a river that flows parallel to the Potomac but enters the Chesapeake Bay directly.All of the streams are dependent on precipitation falling in the two adjacent watersheds, rain and snowfall in a roughly 40,000 square km area

[By the way, the water restrictions in suburban Maryland noted a few days ago have been lifted as the pipe has been repaired, but the Washington Suburban Sanitary Commission is aware that much of its infrastructure is old and potentially at risk for failure. Meanwhile the Montgomery county seat of Rockville, which has its own water system, had declared an emergency and called on residents to curtail water use. That emergency caused by a water main break was ended earlier today. ]

The Washington DC Metropolitan area falls at a boundary in the (arbitrary) division of the US into climate regions. The Drought Monitor at the end of June from the University of Nebraska, Lincoln suggests that the Virginia suburban are at the early stage of drought.

The Guaraní Aquifer - Ground Water in South America II

Despite containing some of the driest areas on earth in Peru and Northern Chile and large arid zones in the vast expanses of east of the Andes, in Patagonia and in Northeastern Brasil, South America is well endowed with water supplies. Five huge river systems – the Amazon, the streams of the Rio de la Plata estuary, the Orinoco, the Magdalena, the São Francisco – and numerous smaller ones along the western slope of the Andes and the Caribbean and Atlantic Coasts make South America a water rich continent. Unlike Asia and Africa where a large fraction of the water supply is already in use, South America has water resources hardly tapped for human uses other than transportation. Hidrovia, noted in an earlier posting, is mostly a transportation proposal

The Guaraní aquifer is one of the largest known underground water deposits. Some even think it is the largest fresh water body on earth, larger in total volume than either Lake Superior or Lake Baikal! It is estimated to contain more than 35,000 cubic kilometers of water (the estimates on the map above are at the high end of the range) in a basin that stretches from tropical Brasil south into Paraguay, Argentina, and Uruguay with a surface extent of well over a million square kilometers. At present, water from the aquifer directly supplies about 30 million people, though it is estimated that it could sustainably support the water needs of 10 times that many. Outflow from the aquifer supplies some of the water in several major rivers including the Paraná and the Uruguay. Among the major aquifers of the world it is one of the least utilized, and except locally around a few communities using the water, there is little evidence pointing to the draw down and even exhaustion of groundwater familiar in large aquifers elsewhere.

With increasing demand for water throughout the world, there will undoubtedly be increased demand for the water in the Guaraní Aquifer. The booming economy of Brasil has increased water demand for urban uses, industry, and especially for agriculture in the recent past. Much of the Brasilian population lives near the aquifer, and the immense metropolitan area of São Paulo is only a few kilometers from its edge.  As with many large aquifers, much is unknown about the quantities of water and patterns of flow below the surface. A large research project by the IAEA (International Atomic Energy Agency) is attempting to discover more about the aquifer in hopes of improving management as water demands increase. All of the countries are members of Mercosur, the Common Market of the South, and there is an effort to use it as a foundation for management of the aquifer as demands for water increase.

During the Cheney-Bush administration the United States held military exercises in Paraguay, and there was a rumor that Bush or members of its family had purchased 100,000 hectares in the northern part of the landlocked country. While there is no compelling evidence to support the contention, local critics argued that the US was engaged in military exercises in a preliminary move to claim water from the aquifer. That is probably incorrect, at least for now, but the Guaraní is likely to be a major focus in debates about the world's water in the very near future. A documentary film about it is currently in production by the Guarani Project.

Urban Water II

Le château d'eau du Peyrou, Montpellier France 2005

©EOP

"One of Montpellier’s more interesting architectural curiosities is the neoclassical temple Chateau d’Eau in the Promenade du Peyrou. Built to hide the reservoir of the Aqueduc St-Clement (completed in 1771) to bring water from the Lez river. The aqueduct is located behind the temple and modeled on the Pont du Gard."

One of the great and continuing challenges of human society has been the supply of water in urbanized areas and the associated issue of removing sewage (an issue we shall not investigate in any detail). Located in a Mediterranean climate, the city of Montpellier in southern France, long a center of medicine and science, was annually faced with the summer drought associated with its climate. Its response was an old one for cities near the shores of the Mediterranean, construction of an aqueduct from a nearby river to the center of the city. Not far away is the famed Pont du Gard, a Roman aqueduct crossing the Gard one of the larger rivers in southern France. That aqueduct brought water to the city of Nîmes, an important Roman settlement which continued to use water brought by the aqueduct long after the fall of the Roman Empire. On a first view one might also attribute the aqueduct and associated works in Montpellier to the Romans, but in fact they were constructed during the ancien regime. Montpellier, world renowned for its university and the associated medical school and also a city that was a hotbed of Protestant religious activity, was a particular focus for the Paris government and resources were freed for construction of its waterworks a couple of decades before the Revolution.

Montpellier was something of a pioneer, for construction of large urban water supply systems was fairly uncommon from Roman times until the 19th century in Europe and the Americas. Most cities used water from adjacent streams along with water from wells or surface seeps and rain collected in cisterns. Much of that water was fouled with wastes from upstream users and sewage from the cities themselves, and water borne illnesses including cholera and typhoid were not rare. Only a few cities sought water from purer sources to meet their needs. The rapid increase in urban populations beginning in the late 18th century along with increasing knowledge about the importance of water (clean water came later) for health was a goad to construction.

Philadelphia's waterworks, also using a classically inspired building as one of its centerpieces (see posting above) was in some degree inspired by two Francophiles who spent significant time in the Pennsylvania city, Thomas Jefferson and especially Benjamin Franklin, both of whom were familiar with Montpellier, Nîmes and waterworks in France.

Water and Food I: Coffee (not really food, of course)

La Bolsa de Café, Buenos Aires, Argentina 2008

©EOP

The interconnectedness of water supply, food supply and the human population was the basic idea prompting this set of courses, and I hope at least a few OLLI members will enroll in all three even if each course is designed to stand independently. The topics of three courses are interdependent in many ways, but we are often inclined to ignore those connections. Over the past few days I have been doing some research on the connections between water supply and food production, and I have discovered a true cornucopia of material (pun intended). 

We need water directly for hygiene and sanitation, but by far the largest human use of water is for agriculture and the production and processing of food. Each food unit we consume is composed of various inputs of which water is a crucial one. Even the crops most tolerant of aridity demand at least a little water to grow and produce food. Many foodstuffs are ravenous consumers of water requiring hundreds or even thousands of liters of water for each kilogram or liter of product. That is a subject we shall look at in some detail in the course and perhaps in future blog postings. Today I would like to introduce the water demands just one thing many people consume regularly, coffee.

Coffee is not really food, and with a little pain - a couple of days of caffeine deprivation headaches - most of us could probably stop drinking it (though I really like the taste of good coffee). Coffee is an obvious user of water, for each cup brewed requires us to draw water from the tap. That single cup of coffee requires not just the cup (125 ml) we put in the coffee maker but a total of 140 liters of water! Not so obvious when we brew the pot is the large amount of water needed to grow, process, and transport the beans to us as well as the water needed to produce  the electricity, dispose of the waste, etc. The Dutch, who are known for their fine coffee and their coffee drinking tradition, have studied the issue and in a paper titled "The water needed to have the Dutch drink coffee" two Dutch scholars have outlined the demand for water related to coffee drinking in the Netherlands, the water footprint of Dutch coffee. It makes for fascinating and thought provoking reading!


By comparison to most meat products, our liquid refreshments, including coffee, tea (30 liters per cup) , and beer (75 liters per 250 ml glass) demand fairly modest quantities of water. The Water Footprint Network, operated from the University of Twente in the Netherlands in cooperation with UNESCO,offers a great set of webpages and downloadable publications on the water demands of lots of different foods and other products and the issue of water footprints.

Hidrovia and Water in South America I

Evening view of the junction of Rio Iguazú (right) with Río Paraná from Argentinian Bank, Brasil to right and Paraguay left (Ciudad del Este high rises in distant background), 2007

©EOP

Water transportation is not going to be a topic for discussion in the course, nor will wildlife conservation issues be emphasized, but they are both related to human water use. At the moment I am also preparing to lead a course on the Southern Cone of South America where the Paraná and its tributaries are important for transportation, for wildlife, and for water supply. The Paraná is navigable for small ocean going ships upstream as far as the Argentinian city of Corrientes, and its branches can be navigated further upstream into Brasil and Paraguay by shallower draft vessels. Landlocked Paraguay has long been dependent on the river for transportation access, and inland Argentinian cities including Corrientes and Rosario are also dependent on river transportation for access to world markets. More recently the commodity production boom in Brasil has greatly increased transportation demand as that country extends its ecumene into the interior.

The Rio de la Plata river system, including the Paraná its largest single stream, is one of the world's great river systems with a flow second only to the Amazon in the Americas.Its flow comes mainly from rainfall in the humid zones of subtropical and tropical southern Brasil, though it is not an exotic river for there is an excess of precipitation over evapo-transpiration in normal years along much of its length. Several huge hydroelectric projects on the Paraná provide much of the power used by Brasil, Argentina and Paraguay and have converted large segments of its upstream basin into slackwater lakes. As yet the Paraguay, a major tributary to the Paraná and navigable in some years into Brasil, has not been dammed.

A problem for navigation is the uneven flow across the year and from year to year. Hidrovia is a project to even out the flow of the Parana by manipulating water in the Pantanal, the immense marshland on the boundary between Brasil and Bolivia. While the project is apparently moribund at the moment, it is likely to be revived. The problem is the Pantanal is one of the world's great wetlands, and one of the largest still largely untouched by human activity. Known for the diversity and density of its wildlife, conservationists argue that it should be preserved in its current state.

In future postings I shall examine Hidrovia in greater detail and look at other aspects of water availability and use in South America.

Suburban Water Problems in Maryland

Head of navigation on the C&O Canal, Cumberland, MD 2009

©EOP

Urban water supply was the subject of yesterday's post. After it was written I found that nearby is a major (sub)urban water supply problem. An urban water system requires almost constant repair and replacement, for just as a stream erodes the rock over which it passes, flowing water in pipes causes them to erode. If the erosion is great enough, then a pipe can break, and a catastrophic spill can follow. The Washington Suburban Sanitary Commission (WSSC) which provides water and sewer services to the Maryland counties adjacent to Washington, DC had a catastrophic spill in 1998. That spill caused several injuries and substantial economic dislocation in Montgomery County along with dangers to public health and safety. Among other damage, a major commuter street was washed out and had to be replaced at considerable expense and inconvenience to commuters and nearby residents.

Yesterday the WSSC had another problem. After tests showed severe erosion, in order to avoid the rupture of a huge trunk water main, the agency was forced to shut off that line and thereby cut water supplies to nearly 2 million users. In turn water users were asked to drastically reduce their water use over the holiday weekend until repairs can be made to the pipe, but as of this morning the voluntary cut backs were not large enough to prevent a potentially disastrous drop in water pressure. With the 4th of July weekend and week following promising to be very hot and dry, lack of adequate water could prove a major problem to those whose water supply is reduced and uncertain.

While I am unaware of the sources of the problems in Maryland, the parlous state of the urban water supply systems in a number of cities due to inadequate investment in new facilities and lack of maintenance of existing water lines is well known. Tens of thousands of kilometers of water lines, from ones leading from the street into offices, shops and dwellings to major lines bring water from distant sources, need replacement in the near future. A large fraction of those lines are owned and operated by municipal and quasi-governmental agencies like the WSSC. The "no taxes" mantra along with the unwillingness of the public to pay higher rates has meant the utilities have been starved for investment and maintenance funds. Perhaps a major event will waken the public to the need for more money. One must hope that event is not a conflagration involving thousands of houses or a public health crisis!

Urban Water Supply

Fairmount Waterworks, Philadelphia, PA 1998

© EOP

Spending several days in Philadelphia earlier this week, I have not done much work on  the water course. The issue of water was not completely absent, for on a visit to the Philadelphia Museum (brown temple like building in the upper section of photo), we parked in a lot above the Fairmount Waterworks, some classic revival buildings of substantial architectural interest on the eastern bank of the Schuylkill River near downtown Philadelphia.With its museum honoring the city's waterworks, the building is also of substantial interest as a surviving element of one of the oldest municipal water supply systems in the world. Originally opened in 1815, the pumping station has been closed for over a century, but it marks the initial source of a reliable supply of clean water for the residents of the Pennsylvania city and the origins of the idea that a supply of potable water was essential for urban success.

Upstream from the waterworks and the dam on the Schuylkill is Fairmount Park. It was originally created to protect the quality of the city's water by limiting development of its watershed, an idea still very much in the forefront of urban water supply planning. Philadelphia today draws its water from a much larger area, but the green space remains one of the largest urban parks in the United States. A number of urban innovations had their origins in Philadelphia, including a fire department created through the efforts of Benjamin Franklin.Its growth to become one of the largest cities in the United States depended on increasing its water supply. Today's water system supplies a vastly larger population spread over a much larger land area than the Fairmount Park pumping station supplied. A good website called Philly H2O has all kinds of information about the city's water supply, including a great map collection.