Apr 092012

A recent report from researchers at the National Autonomous University of Mexico (UNAM) and the Metropolitan Autonomous University (UAM) confirms that the height of the water table below Mexico City is dropping by about one meter a year, as more water is pumped out of the aquifer than the natural replenishment rate from rainfall. About 60% of Mexico City’s drinking water comes from wells, with the remainder piped into the city, mainly via the Cutzamala system. The researchers say that up to 65% more water is taken from some parts of the Mexico City aquifer than the amount replaced each year by natural recharge.

As we reported in a previous post – Why are some parts of Mexico City sinking into the old lakebed? – this has resulted in parts of Mexico City sinking more than seven meters (23 ft) since 1891, with implications for water pipelines, drainage systems, building foundations and the city’s metro network, as well as an increased incidence of ground subsidence.

According to this latest research, the clay soil of the former lake bed below the city is sinking by between 6 and 28 cm/yr in most places, with rates in the southeast part of the city (where numerous wells have been drilled in recent years) sinking by up to 35 cm/yr.

How can the problem of sinking ground be resolved?

The report emphasizes the importance of conserving as much green space as possible within the city, to reduce runoff (and demands on the city’s drainage system) while simultaneously recharging aquifers. The three major alternatives, some combination of which is needed to resolve the problem are:

  • introduce more water-saving strategies so that demand does not continue to increase
  • bring more water from outside the Valley of Mexico (this would be costly and unpopular)
  • feed more wastewater back into the underground aquifers via “surface soaks”. As one example, the National Water Commission (Conagua) has announced plans to build a 200-million-dollar wastewater treatment plant (“El Caracol”) that will inject water back into the aquifer after treatment. It would be Mexico’s first ever large-scale reinjection project.

Perhaps not surprisingly, Mexico City residents pay more for their water than users anywhere else in the country, with an average water rate of US$1.23/cubic meter. Elsewhere, the two states sharing the arid Baja California Peninsula also have higher than average rates of $1.05/cubic meter (Baja California Sur) and $0.94/cubic meter (Baja California). The lowest rate in the country, well below the true cost of supplying water, is in Nayarit, and is just $0.25/cubic meter.

Within Mexico City, access to potable water is far from equally/fairly distributed across the city, as revealed by this thought-provoking quote :

In a study of water access in Mexico City, geographer Erik Swyngedouw found that “60 per cent of all urban potable water is distributed to three per cent of the households, whereas 50 per cent of the inhabitants make do on five per cent of the water”. Critical geographers like Swyngedouw ask us to take note of the spatial nature of power imbalances revealed in patterns of city design and growth: “mechanisms of exclusion… manifest the power relationships through which the geography of cities is shaped and transformed.”  [quote comes from page 31 of Nature’s Revenge: Reclaiming Sustainability in an Age of Corporate Globalization ; the reference is to Erik Swyngedouw’s Social Power and the Urbanization of Water: Flows of Power (OUP 2004).]

This grossly unequal distribution of potable water remains a critical problem that successive administrations in Mexico City and the surrounding State of México have done little to resolve.

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Greenpeace demands action to clean up Mexico’s surface waters

 Mexico's geography in the Press  Comments Off on Greenpeace demands action to clean up Mexico’s surface waters
Apr 052012

Greenpeace activists chose the Juanacatlán Falls (“The Niagara of Mexico”) for their latest protest to call attention to the poor quality of Mexico’s rivers and lakes. They cited government statistics that show 70% of Mexico’s surface water is contaminated. Most of the pollution comes from industrial dumping, rather than municipal sewage.

It is hard to imagine a better choice. The activists, clad in protective clothing and wearing masks to avoid inhaling toxic gases, paddled kayaks into the River Santiago immediately below the malodorous falls and unfurled banners with slogans such as “Mexican rivers, toxic rivers” (see image).

Greenpeace activists at El Salto de Juanacatlán, 22 March 2012. Photo: Greenpeace.

The activists called on the government to commit to a policy of zero dumping of toxic substances into rivers and lakes by 2020, with sanctions for actions leading to pollution and its effects.

In a coordinated action, thirty NGOs in Jalisco announced the creation of the “Broad Front in Defense of Water and Against Privatization ”, demanding actions towards a fully sustainable use of water. They asked government to take the lead in cleaning up the Santiago River and provide urgent medical attention for residents of communities affected by its high level of pollution (see this blog post). They also called for an end to the privatization of water services.

José Luis Luege, the head of Mexico’s National Water Commission (Conagua), the government body overseeing all Mexico’s water resources, recently presented a portfolio of programs for the country’s 13 water regions which are designed to make Mexico’s water usage sustainable.

Conagua calculates that Mexico currently uses 78.4 million cubic meters of water a year. Of this amount, 66.9 billion cubic meters is taken from surface and underground sources (and is fully sustainable), while about 11.5 billion cubic meters come from the unsustainable use of aquifers, where the rates of abstraction exceeds replenishment. The new programs are designed to reduce and eventually end unsustainable aquifer use, replacing it by a mixture of water-saving programs and by building the necessary infrastructure to obtain more water from sources believed to be fully sustainable.

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Will the mighty Colorado River ever reach its delta?

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Feb 062012

A few months ago, we highlighted the outstanding work of photographer Peter McBride. McBride traveled the length of the  Colorado River from its source high in the Rocky Mountains to its vast delta in the otherwise arid Sonoran desert in northern Mexico where the river emptied into the Sea of Cortés (Gulf of California). Now, McBride has released (on Yale Environment 360) a visually stunning video about his experiences tracing the Colorado River. The last third or so of the video focuses on the Colorado delta region in northern Mexico.

McBride follows the natural course of the Colorado “by raft, on foot, and overhead in a small plane, telling the story of a river whose water is siphoned off at every turn, leaving it high and dry 80 miles from the sea.”

The river enters Mexico (see map below) at the Southerly International Boundary where a gauging station records the river’s discharge. Sadly, this river is one of the most altered river systems in the world.The Río Colorado delta wetlands once created ideal conditions for a rich variety of wildlife. Today, the Río Colorado wetlands have been reduced to about 5% of their original extent, and the potential water supply for the rapidly-growing urban centers of Mexicali, Tijuana, Tecate and Rosarito has been compromised.

Map of the Colorado delta

Map of the River Colorado delta. All rights reserved. Click to enlarge.

Related articles:

Rivers, reservoirs and water-related issues are discussed in chapters 6 and 7 of Geo-Mexico: the geography and dynamics of modern Mexico. Ask your library to buy a copy of this handy reference guide to all aspects of Mexico’s geography today! Better yet, order your own copy…

Maintaining the drains and sewers of Mexico City

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Jan 312012

How is Mexico City’s choking sewer system cleaned? Have you ever wondered who is responsible for the gross job of cleaning the city’s sewer system to help ensure it never gets blocked? Well, we did and were surprised at the answer…

To find out, click the link for this 4 minute video clip from our friends at National Geographic:

In previous posts, we looked at the history of attempts to drain Mexico City:

and at the construction of a massive tunnel to improve the city’s drainage:

At present, both the water supply system and the sewer systems of Mexico City are managed by a single government entity, the Sistema de Aguas de la Ciudad de México (SACM).

In 2008, the system’s main existing tunnel was shut down for its first maintenance in 35 years. To maintain the drains and sewers, Mexico City relies heavily on its experienced team of divers, all two of them! They are thought to be the only sewage divers in the world. This 2010 interview from the always interesting blog ediblegeography.com with diver Julio Cou Cámara is a mind-opening read.

In his own words, “What we mostly do is maintenance. We repair pumps, we take out debris—we take out bodies of animals, bodies of people, and all the rubbish. There’s so much rubbish in the drainage system, it’s very harmful to us and to the city. People are always wondering why there’s so much flooding in the city. I can tell you that the city floods because of all the rubbish that creates blockages in our drainage system. If we were maybe a bit more conscious about rubbish and we didn’t throw it on the street, we wouldn’t have this many flooding problems in the city.”

Frankly, this challenging job does not sound like much fun: “We work blindly in the black water. It contains animal poo, human poo, hospital waste… any kind of pollution you can think of. All of that is in the sewage water. That’s where we work.”

So, now you know! The sewers of Mexico City would function far worse if it wasn’t for the unsung heroism of workers like Carlos Barrios and Julio Cou Cámara.

(But if a vacancy comes up, please don’t call)

Jan 232012

As we saw in an earlier post – Attempts to provide drainage for Mexico City date back to Aztec times – Mexico City has serious drainage problems. Because of the shifting subsoil as the land on which the city was built sinks an average of 10 cm/yr, the main drainage tunnels built years ago no longer have the slope (grade) they need to work efficiently. At least one of the feeder tunnels now slopes in the wrong direction!

This has greatly increased the risk of catastrophic flooding occurring. After years of discussion, authorities decided a few years ago that the only viable solution was to construct another major drainage tunnel to take pressure off the existing system and increase the maximum drainage rates following heavy storms.

The new tunnel, known as the Eastern Drainage Tunnel (Túnel Emisor Oriente), is said to be the world’s largest ever drainage tunnel and should be completed within the next couple of years. It is 7 m (23 ft) in internal diameter (wide enough for a tractor trailer) and can carry up to 150 cubic meters of water a second.

Map of tunnel route

Map of tunnel route; the new tunnel is in red, the existing Central Tunnel is in blue

The tunnel is 62 km (39 mi) long. It starts from the interceptor channel of Río de los Remedios and ends in a treatment plant in Atotonilco de Tula (Hidalgo), close to where the existing Central Drainage Tunnel flows into the El Salto River. Atotonilco receives 725 million cubic meters of water each year carrying 180,000 tons of garbage. Some of the treated water will be piped to the Mezquital Valley Irrigation District in Hidalgo where water usage exceeds natural replenishment rates. The remainder of the treated water will be given additional (tertiary) treatment before being piped into the overexploited underground aquifers to replenish them.

photo of new tunnelThe Eastern Drainage Tunnel construction project is one of Mexico’s largest engineering undertakings ever. The total investment (45% government, 55% private) is almost a billion dollars. Six massive boring machines are working in coordination, each boring a 10km section of the tunnel. The work is challenging, partly because of the varied nature of the rocks (limestone, volcanic rock, sand and clay) and partly because parts of the tunnel are as much as 200m (equivalent to 40 stories) below the surface.

Ventilation shaft of new tunnel

Ventilation shaft of new tunnel

Mexico’s 2011 drought is raising the price of basic foodstuffs

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Dec 052011

This year’s drought – see Many states in Mexico badly affected by drought is now widely viewed as the worst to occur since modern record-keeping for precipitation began about 80 years ago.

Short-term droughts are not unusual in Mexico. As the graph shows, there is a clear cyclical pattern to the timing of short-term droughts in Mexico. This is because most of the country receives almost all its annual precipitation in just a few months, from May or June (depending on precise location) to September-October.

The scale of the current drought is readily apparent from the graph. This year, far more of the country is affected, and the level of drought is far more severe.

Seasonal drought in Mexico, 2003-2012
Seasonal drought in Mexico, 2003-2012. Click to enlarge.

The drought is having numerous adverse impacts

It is already having an effect on food prices. Several of the basic foodstuffs  making up Mexico’s basic basket of goods for economic indices such as the inflation index, have risen sharply in price in recent months. A shortage of corn has led to a 70% increase in imports of yellow corn from the USA.

Incredibly, Mexico, the home of corn, is now the world’s second largest importer. Corn, as we have noted in previous posts, is a vital ingredient in Mexican cuisine, and is particularly important in the southern half of the country, especially in the more rural and indigenous areas. The shortage of corn has led to a rise in the price of tortillas, a dietary staple in almost all of the country. Tortilla prices have risen up to 18%, many times Mexico’s overall inflation rate of about 3.5%.

The production of chiles, another staple of the Mexican diet, has also fallen due to the drought, by an estimated 40%. In Zacatecas, that state’s 2,500 chile-growers will have produced 120,000 tons of green chile and 62,150 tons of dried chile this year, even though they have only been able to harvest chiles twice this year, rather than the normal four times. The state is the leading source of dried chile in Mexico. The area cultivated for chiles in Zacatecas has also fallen this year, to 31,300 hectares. The decrease in production has had a direct impact on the number of harvesting jobs available, since each hectare of chile cultivation usually means 150 seasonal jobs. The production shortage for chiles will be offset by more imports from Peru and China.

At latest count, 770 municipalities are now suffering from drought, and at least 2.5 million people in 1500 communities are left with insufficient drinking water. In the state of Durango alone, more than one million people are currently experiencing extreme drought, and 149 communities are completely without drinking water.

The long-term outlook is not favorable for these areas since climate change is expected to increase both the frequency and severity of droughts over the next twenty to thirty years.

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Many states in Mexico badly affected by drought

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Nov 232011

Much of Mexico is currently affected by some degree of drought (see map below). The National Meteorological Service (SMN) reports that September was one of the driest months in some 70 years. All the signs suggest this is the worst year for drought since 1941. The worst affected states are Sonora, Chihuahua, Coahuila, Durango, Nuevo León and Zacatecas. (Paradoxically, some parts of southern Mexico, especially in the states of Oaxaca and Tabasco, have experienced serious flooding in recent months).

In the drought zones, emergency programs are getting underway to provide temporary work for many rural dwellers and to supply potable water to the worst affected settlements. In addition to crop losses, up to one million head of cattle will have been put down by year-end in northern states as a direct result of the drought, since farmers do not have sufficient fodder available to feed them as usual.

While some cattle have been exported to the USA, local meat prices will be driven down by the increase in supply, making many farmer’s livelihoods even more precarious. Many farmers will need federal assistance to overcome this latest crisis.
Areas suffering from drought, October 2011

Areas suffering from short-term and long-term drought, October 2011. Click map to enlarge

Durango faces the worst drought for 100 years

In Durango, water has been provided to 32,691 residents in 10 municipalities, with another 36 municipalities to be supplied in the current phase of emergency assistance. Officials in Durango say it is the state’s worst drought for 100 years, with most larger reservoirs in the state now holding between 20% and 40% of their capacity; one reservoir is already down to less than 10% of its.

Irregular rains over the past few months have done little to replenish reservoirs, leaving farmers in despair. The long-range forecast does not appear to offer them much consolation, with the drought expected to last well into next year.

By mid-September, some parts of Durango had received less than 140 mm of precipitation so far ths year, well below the 425 mm registered for the same period in 2010.  The only hope for local farmers appears to be if late season hurricanes bring far more rain than expected to this region.

The drought news from other states

In Chihuahua, 589 tankers have delivered water to settlements housing 62,000 in 15 different municipalities: Guazapares, Janos, Manuel Benavides, Morelos, Moris, Ocampo, Ojinaga, Urique, Uruachi, Aldama, Balleza, Bocoyna, Guachochi, Guadalupe and Calvo.

In Zacatecas, a “state of emergency” has been declared for 52 of the state’s 58 municipalities. More than 150 communities are seriously affected, especially smaller communities in the municipalities of Fresnillo, Jerez, Guadalupe, Tlaltenango, Nochistlán, Atolinga, Villa de Cos, Genaro Codina and Teúl de Gonzalez Ortega.

Drought has affected 288,000 hectares of rain-fed crops in Guanajuato. The greatest losses are of corn, beans, wheat, sorghum and other grains, with the worst-hit areas located in the northern part of the state. More than a million liters of potable water have been supplied to 18,000 inhabitants living in 133 settlements in the state, located in the municipalities of Atarjea, Doctor Mora, San Diego de la Unión, San Felipe, Santa Catarina, Tierra Blanca, Victoria and Xichú.

Horticulturalists in Sinaloa growing vegetables, grains and fruit for export want 30 million dollars in emergency funds to restore irrigation to 700,000 hectares of productive land. More than 200,000 seasonal jobs are at risk.

Related post:

Mexico’s water resources and water-related issues are the subject of chapters 6 and 7 of Geo-Mexico: the geography and dynamics of modern Mexico. Ask your library to buy a copy of this handy reference guide to all aspects of Mexico’s geography today! Better yet, order your own copy…


Mexico, USA and Canada cooperate to produce monthly drought maps

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Nov 192011

The North America Drought Monitor (NADM) is a “cooperative effort between drought experts in Canada, Mexico and the United States to monitor drought across the continent on an ongoing basis”. The program began  in 2002 . The NADM is an extension of an earlier version that was limited to the USA.

The NADM combines multiple indices and local information to produce “drought monitor” maps that best reflect the consensus of numerous scientists, some working at state or federal level, and others working in tertiary education and research.

What exactly is a “drought”?

The basic definition of a drought is a prolonged period of abnormally low precipitation. In practice, this means a period when precipitation is significantly less than would normally be expected for the time period under consideration. The amount of precipitation that is “normal” varies greatly from one area to another, and can also vary with the seasons. Low precipitation in a desert would not necessarily indicate a drought! On the other hand, low precipitation in a rainforest almost certainly would indicate a drought. Since most of Mexico experiences a dry season and a rainy season each year, this further complicates the picture. Not only is it important to know how much precipitation falls, but it is also important to know when it falls.

Areas suffering from drought, October 2011
Areas suffering from short-term and long-term drought, October 2011. Click map to enlarge

This definition must be borne in mind when looking at the Drought Monitor maps, as should the seasonality of precipitation throughout most of Mexico, and the distribution of precipitation, which varies greatly from north to south.

The NADM maps show that the drought situation can change quite rapidly from one month to the next. (Use the link above to compare February and March 2011, for example, or March and April 2011).

In a future post, we will take a closer look at the impacts of the drought (shown on the map) that currently affects much of northern Mexico.

Mexico’s freshwater aquifers: undervalued and overexploited

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Nov 052011

Mexico’s groundwater aquifers are a very important resource. About 64% of public water supplies come from wells sunk into aquifers. Mexico City, Monterrey and several other metropolitan areas rely heavily on aquifers. Aquifers also provide about one-third of all the water for agriculture and livestock.

The largest aquifer resource in terms of renewable water availability is in the Yucatán Peninsula, with about a third of the national total. A large portion of the rainfall in the Yucatán seeps into its aquifers; there are virtually no rivers to carry rainwater to the ocean. The states of Chiapas and Tabasco, where rainfall is the heaviest, account for about a quarter of Mexico’s aquifer resource. The next largest sources are the Balsas and Lerma–Santiago basins but each holds less than a tenth of the national total.

Map of overexploited aquifers and areas of salinization

Overexploited aquifers and areas of salinization (Fig 6-7 of Geo-Mexico; all rights reserved)

According to the National Water Commission, 104 of the country’s 653 identified aquifers are overexploited in that more water is withdrawn each year than is naturally replaced. The velocity of water movements underground can be astonishingly slow; it may take rainwater water tens or even hundreds of years to reach the aquifer it is replenishing. (For a curious case of replenishment rates, see The Enchanted Lake).

The number of overused aquifers has increased rapidly in recent decades from 32 in 1972, to 80 in 1985, and 104 in 2004. When coastal aquifers are over-exploited, seawater seeps in to replenish the aquifer, and eventually the aquifer can become too salty to be used for irrigation. Salt-water intrusion is a significant problem for 17 aquifers located in Baja California, Baja California Sur, Colima, Sonora and Veracruz (see map).

Nearly 60% of the total groundwater extracted is withdrawn from overexploited aquifers. As expected,  the over-exploited aquifers are in the heaviest populated and the most arid areas. Total water extraction exceeds recharge in Mexico City, Monterrey and other large northern metropolitan areas as well as irrigated areas of Sonora, the central northern plateau, the Lerma basin and Baja California.

Related posts:

Mexico’s water resources and water-related issues are the subject of chapters 6 and 7 of Geo-Mexico: the geography and dynamics of modern Mexico. Ask your library to buy a copy of this handy reference guide to all aspects of Mexico’s geography today! Better yet, order your own copy…

Which cities have the best and worst water systems in Mexico?

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Aug 182011

The Water Advisory Council (CCA), a Mexican NGO specializing in water research, education and policy, has published its 2011 report on Mexico’s water management, sewerage and sanitation. The report looks at data for 50 Mexican cities, each of which has a population in excess of 250,000.

The report —Gestión del Agua en las Ciudades de México (Water Management in Mexican Cities)— uses data for 20 variables to develop the following 10 indicators: drinking water coverage; drainage and sewerage coverage; continuity and extension of services; productivity; metering; physical efficiency; business efficiency; operating income; wastewater treatment; and institutionalization.

In terms of overall performance, the city of León came top, followed by Saltillo, Monterrey, Mexicali, Aguascalientes, Cancún and Tijuana. Of the top six, three (Saltillo, Aguascalientes and Cancún) are managed by private operators, while León, Mexicali and Tijuana are public water systems. There is clearly no discernible difference between the performance of private operators and the best public systems. Towards the bottom of the rankings, all the cities have public water systems. The worst-ranking cities include several in the State of Mexico, as well as others in the south and southeast of the country.

For water quality, the leader was Ciudad Victoria, followed by Colima, Monterrey, León, Torreón, Tepic and Hermosillo. The ten worst were Villahermosa, Cuernavaca, Acapulco, Oaxaca, Xalapa, Chetumal, Chilpancingo, Celaya, Chimalhuacán and Campeche.

For efficiency, the leader was Saltillo, followed by León, Monterrey, Tijuana and Aguascalientes. The least efficient were Ecatepec, Campeche, Villahermosa, Celaya, Chilpancingo and Chimalhuacán.

The report says that where the private sector is involved, the important issues are transparent tenders; clear, balanced and flexible contracts; effective controls to prevent abuse; legal certainty; and effective regulation with stable, long-term regulating agencies.  The authors also emphasize the importance of pricing that reflects costs, and of removing the payment exemptions currently given to government agencies.

The Water Advisory Council argues that the Federal Agency for Environmental Protection (PROFEPA) should be in charge of all water monitoring, though its powers need strengthening to ensure it can fully carry out its mandate.