Resources about the geography of chinampas, an ancient form of sustainable agriculture

 Books and resources  Comments Off on Resources about the geography of chinampas, an ancient form of sustainable agriculture
Sep 302013

This post describes some of the many online resources about chinampas, one of Mexico’s ancient and most important indigenous forms of sustainable agriculture.

For photos, the best starting point is Dr. Jason Turner’s site about chinampas which includes an extensive bibliography about chinampas as well as several “Virtual Field Trips” (photo sequences). Even though these photo sequences often lack any accompanying descriptions or captions, they cover a wide range of ideas, and are organized in self-explanatory groups such as:

For an article describing a recent tour of a working chinampa in Xochimilco’s Ecological Reserve. illustrated with great photos, try Touring Xochimilco’s farms with De la Chinampa written by Lesley Téllez (self-described food writer with a “deep love for Mexican food and culture”) on her blog “The  Mija Chronicles”.

Youtube also has a variety of chinampa-related resources. In English, the best introduction is Discovery Atlas – Mexico: Xochimilco which provides a good background to the history and covers the basics.

Two Spanish-language Youtube resources provide valuable additional information. Each video lasts about 5 minutes, but neither video has English language subtitles.

The first is Divina Ciudad: De la chinampa a la mesa which looks at one specific project designed to help raise public awareness and aid the conservation of the remaining chinampas in Xochimilco, on the south-eastern outskirts of Mexico City. This project supplies consumers with fresh produce grown on the chinampas in Xochimilco or sourced from within 150 km. See the project’s website – De La Chinampa – for more information.

The second Spanish language video is Profeco TV Reporte Especial: Productos de la Chinampa, un ejemplo de consumo sustentable, This video, made by the federal consumer protection agency Profeco, explains how the produce grown on the chinampas is pesticide-free and relies on sustainable production methods. It calls on viewers to “learn more about the method and help ensure that chinampas do not disappear.”

Book (Spanish)

  • Rojas R., Teresa (Coord) 1995. Presente, pasado y futuro de las chinampas. Mexico DF: Ciesas/Patronato del Parque Ecológico de Xochimilco A.C. This is a collection of 25 papers presented at a 1990 international conference in Mexico City.

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Sep 192013

An innovative aerial public transport system is being proposed in Mexico City as a way to help reduce traffic congestion and increase personal mobility. TUEP (Transporte Urbano Elevado Personalizado), a Mexican start-up, is being supported by the Federal District’s Secretariat for Science, Technology and Innovation (Seciti) and has manufacturing support from vehicle manufacturer DINA.

TUEP says that its system of aerial cabins offers more flexibility than cable cars and will save energy costs and take some vehicles off the roads, reducing emissions. It proposes a series of routes, each 5 to 10 kilometers long, linking densely populated residential areas to the city’s existing Metro and Metrobús networks.

The proposed system is fully automated. The aerial cabins, each seating two adults or an adult with two children, travel along a steel cable and can be diverted on and off the main route into a series of “docking stations” for passengers to alight or disembark. Each cabin is individually controlled by its passengers who select their destination using push button controls. This 2-minute Spanish-language Youtube news clip shows how the system works:

Each 5-kilometer stretch would be able to transport up to 5,700 passengers an hour at full capacity, at an average velocity of 4 m/s (14.4 km/hr). Cabins would travel about 10 meters (30 feet) apart, which should mean short wait times for passengers, who would pay about 6 pesos (less than 50 cents US) per trip.

Constructing the system will require posts placed every 50 meters along the route, with docking stations every 1000 meters or so. The system is being designed to be installed along avenues that currently have a median divide, so that there is minimum disruption to alternative forms of transport. According to its proponents, building TUEP lines would be at least 40% cheaper than adding additional Metrobús routes and only a fraction of the cost of expanding the city’s Metro system.

More details and images of the proposed system are offered in this 4-minute silent video:

TUEP has suggested 18 routes that are worthy of feasibility studies, which include Marina Nacional, Río San Joaquín, Taxqueña-Miguel Ángel de Quevedo, Lázaro Cárdenas, Constituyentes-Santa Fe and Eje 10. If all the proposed routes were built, the TUEP network would have a total length of 135 kilometers, and would have the capacity to handle up to 37 million trips a year.

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Sep 092013

Prior to European contact in 1519, what did the Aztec people eat?

The basis of Aztec diet was corn (maize). They cultivated numerous varieties of corn, as well as many other crops including beans, amaranth and squash. Some dishes were seasoned with salt and chili peppers. This mix of items provided a balanced diet that had no significant vitamin or mineral deficiency.

In addition, the Aztec diet included tomatoes, limes, cashews, potatoes, sweet potatoes, peanuts, cacao (chocolate), wild fruits, cactus, mushrooms, fungi, honey, turkey, eggs, dog, duck, fish, the occasional deer, iguana, alongside insects such as grasshoppers. From the lake water, they scooped high protein algae (tecuitlatl), which was also used as a fertilizer.

How did they obtain their food?

The Mexica (who later became the Aztecs) faced a particular dilemma, largely of their own making. Mexica (Aztec) legend tells that they left their home Aztlán (location unproven) on a lengthy pilgrimage lasting hundreds of years. They were seeking a specific sign telling them where to found their new capital and ceremonial center. The sign was an eagle, perched on a cactus. Today, this unlikely combination, with the eagle now devouring a serpent, is a national symbol and appears on the national flag.

Artist's view of the Aztec capital Tenochititlan in the Valley of Mexico

Artist’s view of the Aztec capital Tenochititlan in the Valley of Mexico

The dilemma arose because they first saw this sign, and founded their new capital Tenochtitlan, on an island in the middle of a lake in central Mexico. An island linked by causeways to several places on the “mainland” might have had some advantages in terms of defense, but supplying the growing settlement with food and fresh water was more of a challenge.

Much of their food came from hunting and gathering, and some food was brought by long-distance trade, but space for farming, especially on the island, was at a premium.

The Aztecs solved their dilemma of how to supply food to their island capital by developing a sophisticated wetland farming system involving raised beds (chinampas) built in the lake (see image below). Originally these chinampas were free-floating but over time they became rooted to the lake floor. The chinampas were separated by narrow canals, barely wide enough for small boats or canoes.

Artist's representation of chinampa farming

Artist’s representation of chinampa farming

From an ecological perspective, these chinampas represented an extraordinary achievement, a food production system which proved to be one of the most environmentally sustainable and high-yielding farming systems anywhere on the planet!

Constructing and maintaining chinampas required a significant input of labor, but the yields per unit area could be very high indeed, especially since four harvests a year were possible for some crops. The system enabled fresh produce to be supplied to the city even during the region’s long dry season, whereas food availability from rain-fed agriculture was highly seasonal.

Artist's interpretation of chinampa construction (from Rojas 1995)

Artist’s interpretation of chinampa construction (from Rojas 1995)

The planting platforms or chinampas were built by hand, with alternate layers of mud, silt and vegetation piled onto a mesh of reeds or branches. Platforms, often but not necessarily rectangular, were about 10 meters wide and could be 100 meters or more in length. Willow trees were often planted on the edges of platforms to help stabilize them and provide shade for other plants and for the canals that separated the platforms. Interplanting crops was common, and polyculture was the norm. For many crops, multicropping (several crops in a single year) was possible.

Because the planting platforms were close to water, extremes of temperature were dampened, and the likelihood of frost damage to crops reduced. The root systems of crops had reliable access to fresh water (sub-irrigation). The canals provided a variety of habitats for fish. The mud from the bottom of canals was periodically dredged by hand and added to the platforms, supplying nutrients and preserving canal depth. Together with the regular addition of waste organic material (compost), this replenished the platforms and meant that their fertility was maintained over very long periods of time.

The system could even cope with polluted water, since the combination of constant filtration on the platforms, and aquatic weeds in the canals, partially removed most impurities from the water.

Where can chinampas be seen today?

Archaeologists have found vestiges of chinampas in several regions of Mexico, some dating back almost 3000 years.

Mexico’s best known chinampas today are those in Xochimilco on the south-eastern outskirts of Mexico City. Xochimilco is a Unesco World Heritage site, but faces heavy pressure from urban encroachment and highway construction. Xochimilco’s canals (with chinampas separating them) are some of the last surviving remnants of the large lake that occupied this valley when the Mexica founded Tenochititlan.

Xochimilco (Wikipedia; creative commons)

Xochimilco (Wikipedia; creative commons)

Visiting Xochimilco’s canals and market is a popular weekend excursion for Mexico City residents and tourists alike. However, the modern-day chinampas of Xochimilco are not the same as they would have been centuries ago. First, the total area of chinampas in Xochimilco is only a fraction of what once existed. Secondly, some of the chinampas have been abandoned, while on others chemical fertilizers and pesticides are often used. Thirdly, the area now has many exotic species, including introduced species of fish (such as African tilapia and Asian carp) that threaten native species. Numbers of the axolotl (a local salamander), a prized delicacy on Aztec dinner tables, are in sharp decline. Fourthly, the water table in this area fell dramatically during the last century as Mexico City sucked water from the underground aquifers causing local springs that helped supply Xochimilco to dry up completely. Rubble from the 1985 Mexico City earthquake was also dumped in Xochimilco’s canals.

Lakes in some other parts of Mexico were also used for chinampa farming. For example, in Jalisco, just west of Guadalajara, Magdalena Lake “was a prime source of food for the 60,000 or so people living close to the Guachimontones ceremonial site (settled before 350 BC) in Teuchitlán. They learned to construct chinampas, fixed mud beds in the lake, each measuring about 20 meters by 15 meters, which they planted with a variety of crops… The remains of hundreds of these highly productive islets are still visible today.” (Western Mexico: A Traveler’s Treasury, p 69)

Chinampa farming was one of the great agricultural developments in the Americas. It was, and still can be, an environmentally-sensitive and sustainable method of intensive wetland agriculture.

If you enjoyed this…

You might well enjoy my latest book: Mexican Kaleidoscope: myths, mysteries and mystique

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Aug 052013

A recent study published by the Clean Air Institute analyzed air pollution in 22 Latin American cities:

  • Air Quality in Latin America: An Overview (May 2013; pdf file)

Six Mexican cities were included in the study: Mexico City, Guadalajara, Monterrey, Puebla, Ciudad Juárez and León. However, only limited data were available for Puebla, Cd. Juárez and León. One of the main conclusions of the study is that Mexico has about the worst urban air pollution in Latin America. It is believed to be responsible for about 15,000 deaths in Mexico each year.

The focus was on the following air pollutants:

  1. Particulate matter is divided into two measures; particles less 2.5 microns in diameter (PM2.5) and those less than 10 microns (PM10). PM2.5 pollution is extremely harmful because it penetrates deep into lungs causing inflammation and worsening heart and lung diseases. This can be fatal.
  2. Ozone is formed in the air when oxides of nitrogen and volatile organic compounds mix with intense sunlight. The very intense sunlight in Mexican cities makes them particularly prone to ozone pollution.
  3. Nitrogen dioxide (NO2) is caused by high temperature combustion of fossil fuels in vehicles, factories and power plants. It can aggravate lung diseases as well as contribute to ozone and fine particle pollution.
  4. Sulfur dioxide (SO2), which also comes from burning fossil fuels, contributes to heart and respiratory disease. Unfortunately, not all of the 22 cities had data on all four pollutants. Consequently comparisons among cities are a bit limited.

According to the study, Mexican cities had some of the worst urban particulate pollution in Latin America, significantly above WHO standards. Of the 16 cities with data, Monterrey had by far the worst PM10 pollution with 85.9 micrograms per cubic meter (ug/m3); considerably worse than the perennially dusty Lima with 62.2 ug/m3. Guadalajara came second with 70.1 ug/m3, Mexico City was 6th with 57.0 ug/m3, and León placed 11th with 39.0 ug/m3, even worse than Sao Paulo at 36.5 ug/m3. Though not in the study, Mexicali has worse PM10 pollution than Monterrey. Also Monterrey’s PM10 levels are much better than many major world cities including Cairo, Delhi, Kolkata, Beijing, Chengdu, Bangalore, Shanghai, Dacca, Jakarta, and Karachi.

Mexico City air quality in 1980 (Photo: Tony Burton)

Mexico City air quality in 1980 (Photo: Tony Burton)

Mexico did a bit better with respect to the more serious PM2.5. Of the 11 cities with data, Bogota was worst with 35.1 ug/m3 followed by Lima at 31.5ug/m3 and San Salvador and Montevideo at 28.0 ug/m3. The two Mexican cities with data, Mexico City (26.2 ug/m3) and Monterrey (25.9 ug/m3) were 6th and 8th.

Mexican cities also have some of the highest levels of ozone pollution. Of the ten cities with data, five of the six worst were Mexican cities. Guadalajara had the highest ozone pollution with 69.3 25.9 ug/m3 followed closely by León 68.9 at ug/m3. Mexico City was 4th (59.4 ug/m3); Monterrey was 5th (55.2 ug/m3); and Cd. Juárez came 6th (46.3 ug/m3), just ahead of Quito (44.1). Much better ozone levels were recorded by Sao Paulo (36.0 ug/m3), Santiago (28.8 ug/m3) and Bogota (21.1 ug/m3).

Cities in Mexico also had high levels of nitrogen dioxide. The highest levels were in Montevideo (70.0 ug/m3), but Guadalajara (57.2ug/m3), Mexico City (54.2 ug/m3) and León (45.5 ug/m3) placed 2nd, 3rd and 4th worst among the 14 cities with data. Monterrey was much better with the third lowest nitrogen oxide level (29.0 ug/m3), trailing only Lima (12.8 ug/m3) and Quito (23.3 ug/m3).

Mexican cities were also among the worst in terms of sulfur dioxide pollution. Of the 13 cities with data, León had by far the highest level with (23.4 ug/m3), followed by Medellin (16.0 ug/m3). Mexico City was 3rd worst (15.3 ug/m3); Monterrey was 4th (13.1 ug/m3); and Guadalajara was 6th (8.6 ug/m3).

In summary, the study indicates that Mexico has about the worst urban air pollution in Latin America. Fortunately, Mexico City, which used to be considered one of the most polluted cities in the world, has significantly improved its air quality in the last few decades. (see Rhoda and Burton, Geo-Mexico: The geography and dynamics of modern Mexico, p 177)

On the other hand, other major cities in Mexico have not had the same experience. The data in this study appear to suggest that among Mexico’s three biggest cities, Guadalajara has the worst air pollution followed by Mexico City and then Monterrey. (This study found insufficient data for comparisons with Puebla, Cd. Juárez and León.)

Other posts on urban air pollution:

Popocatepetl Volcano puts on an explosive show

 Mexico's geography in the Press  Comments Off on Popocatepetl Volcano puts on an explosive show
Jul 102013

This 30-second video update on the eruption of Popocatepetl Volcano speaks for itself. Webcams have made the life of armchair geologists (even those of us who quite like exploring volcanic craters, provided the volcano in question is extinct or at least dormant) a whole lot easier!

The alert level remains at Yellow Phase 3, the highest stage before the two “Alarm” stages of Red 1 and Red 2.

Travel tips:

Several international flights into and out of Mexico City over the past week have been either diverted to other airports or cancelled. If you are flying into Mexico City in the next few days, check with your airline.

Ash has fallen (in varying amounts) over many parts of the city during this time. To avoid getting any ash into your lungs (not good!), consider wearing a damp face mask wherever/whenever the air is not clear.

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Tultepec: the fireworks capital of Mexico

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May 252013

No Mexican festival is complete without a dazzling display of fireworks. Gunpowder was unknown in Mexico prior to the arrival of the Spaniards, but its use in fireworks quickly caught on. Firework production is usually a small-scale family affair, and there are workshops specializing in fireworks throughout the country. The undisputed  capital of fireworks is Tultepec, a settlement with 130,000 inhabitants on the northern edge of Mexico City. Generations of expertise have led to Tultepec becoming the source for about half of all the fireworks manufactured in Mexico.

  • Tultepec: Mexico’s Skyrocket Central from The Southwest Center, by Dan Duncan (26-min video)

To celebrate its skilled pyrotechnic craftsmen, Tultepec hosts a 9-day National Pyrotechnic Festival in March each year. The festival, first held in 1989, includes competitions for the best castillos (castles) and toros (bulls) or toritos (little bulls). Castillos can be several stories high, with an intricate interconnected network of sections representing saints, animals, flowers, birds and other designs. Toritos, first recorded in the nineteenth century, are bull-shaped frames placed over the heads of willing volunteers. As the firecrackers explode, the toritos are carried through the streets or dance in imitation of a bull fight as young bystanders pretend to be matadors. About 250 toritos ran the streets of Tultepec in 2013.

The manufacturing of fireworks is tightly controlled by the military, but accidents are all too common and often serious, sometimes fatal. About 2,000 people work directly in the industry, in some 300 small workshops. The creativity of these coheteros (fireworks makers) knows few limits. For example, mid-way through this video, look for the small, firework-propelled vehicle that goes alternately forwards, then backwards, entirely on its own once its fuse has been ignited.

Want to read more?

  • Mexico’s Fireworks Capital by Matthew Power

How can Mexico City find sufficient water?

 Updates to Geo-Mexico  Comments Off on How can Mexico City find sufficient water?
May 202013

What happens if or when Mexico City needs more water than it is using at present? There are several options, depending on whether authorities choose to modify demand, supply, or both in order to improve the future situation.

In terms of managing (reducing) demand, conservation measures are one possibility. Changing consumer habits may require not only educational programs, but also usage tariffs that reflect the true costs of supply, and that encourage consumers to install water-saving devices and introduce water-saving practices in their daily lives. Demand would also be reduced if less water was lost through leakage. As mentioned in a previous post, in 2009, the National Water Commission (Conagua) estimated that a staggering 40% of potable water nationwide was being lost through leaks in city and municipal systems, with a further 20% not properly accounted for due to billing errors and clandestine connections.

Managing demand may be easier to achieve than managing supply, given that recent efforts to increase supply have met with concerted opposition from environmentalists and the people living in the areas from which water would be transferred to the city. In the last half of the twentieth century, while one political party (PRI) held power, it was possible for politicians to largely ignore the conflicts resulting from inter-basin transfers, arguing that their “solutions” served a national need. Now that local, state and federal politics are more contested, that approach is potential political suicide.

From a political perspective, the most acceptable source of additional water for Mexico City would probably be the recently identified deep aquifer described in Mexico’s major cities confront serious water supply issues. However, that discovery requires further research before its maximum sustainable yield can be determined or it can be brought into service.

Less politically acceptable are the various proposals to bring water from elsewhere to satisfy the thirst of Mexico City. One of the most frequently voiced suggestions is to add a fourth phase to the Cutzamala scheme (see Where does Mexico City get its water from?) to increase the amount of water it supplies by more than 25% to 24 m³/s. In addition, the plan would provide treatment for 42 m3/s of wastewater. This fourth phase, known as the Temascaltepec project (see map), would require the construction of a 120-meter-high, 740-meter-long dam on the Temascaltepec River to create a reservoir with a capacity of 65 million m³.

Map of the Cutzamala project

Map of the Cutzamala project. Click to enlarge.

Aqueducts and a 19-km-long tunnel would carry the water to the Valle de Bravo reservoir. The estimated cost would be $500 million. The Temascaltepec project is opposed by environmentalists and locals and is not likely to get under way any time soon. The residents of the villages near the proposed dam site are afraid that the project would cause their local springs to dry up and would adversely impact their farming of maize, sugar cane, banana, tomato, melon and peas.

To the south of Mexico City, an entirely different proposal is to bring water from the Amacuzac, Tecolutla and Atoyac Rivers, by damming the Amacuzac River, creating a 67 km2 reservoir (between the states of Morelos, Guerrero and Puebla) capable of storing 4,000 million cubic meters. Supplying Mexico City would require a 160 km long aqueduct, and would involve pumping water to a height of 1825 meters, requiring up to 5% of Mexico’s annual national electricity production. On the plus side, this could reduce the future abstraction of groundwater by as much as 50 m³/s.

Related posts:

Where does Mexico City get its water?

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May 092013

Mexico City is one of the world’s largest cities, and the metropolitan area of Greater Mexico City (map) extends well beyond the borders of the Federal District (Mexico City proper) into neighboring states, especially the State of Mexico.  The total population of Greater Mexico City is about 22 million, all of whom need safe access to water.

An old joke relates how engineers initially rejoiced at successfully draining the former lake on which Mexico City was built (something the Aztecs had tried, but failed to achieve), only to discover that the city now lacked any reliable source of fresh water for its inhabitants (something the Aztecs had successfully managed by building a system of aqueducts). Water has been a major issue for Mexico City ever since it was founded almost 700 years ago.

The Mexico City Metropolitan Area’s water supply is currently calculated to be around 82 m³/s. (The precise figure is unclear because many wells are reportedly unregistered). The main sources of water (and their approximate contributions to total water supply) are:

  • Abstraction of groundwater (73%)
  • Cutzamala system (18%)
  • Lerma system (6%)
  • Rivers and springs (3%)

In several previous posts we have looked at several issues arising from groundwater abstraction:

In this post we focus on the Cutzamala system (see graphic), one of Mexico’s most ambitious engineering feats of its time.

Cutzamala scheme

Cutzamala scheme (click to enlarge). Source: IMTA (1987)

The Cutzamala system supplies potable water to 11 boroughs (delegaciones) of the Federal District and 11 municipalities in the State of Mexico. The Cutzamala system is one of the largest water supply systems in the world, in terms of both the total quantity of water supplied (about 485 million cubic meters/yr) and in terms of the 1100 meters (3600 feet) difference in elevation that has to be overcome. The system cost about $1.3 billion, and was undertaken in three successive phases of construction, completed in 1982 (Villa Victoria dam), 1985 (incorporation of the Valle de Bravo and El Bosque dams, originally built in the 1940s and 1950s) and 1993 respectively.

As Cecillia Tortajada points out in Who Has Access to Water? Case Study of Mexico City Metropolitan Area, the investment of $1.3 billion was, at the time (1996), “higher than the national investment in the entire public sector in Mexico… in the areas of education ($700 million), health and social security ($400 million), agriculture, livestock and rural development ($105 million), tourism ($50 million), and marine sector ($60 million).”

The system includes 7 dams and reservoirs for storage, 6 major pumping stations (P.P. on the graphic) and a water purification plant. The volumes stored in the system are dependent on previous years’ rainfall. Water is transferred to the Valley of Mexico from more than 150 km away via reservoirs, pumping stations, open channels, tunnels, pipelines and aqueducts.

The Cutzamala system incorporates the Valle de Bravo and El Bosque dams, built originally as part of the “Miguel Alemán” project that generated hydro-electric power from the headwaters of the Cutzamala River (hence the name for the whole system). The reservoir at Valle de Bravo is an important resource for tourism and watersports. The hydro-electric power scheme is no longer functioning. The Cutzamala system has the capacity to supply up to 19 m³/s of water to the Valley of Mexico. In practice, it supplies almost 20% of the Valley of Mexico’s total water supply (usually quoted as being 82 m³/s).

The pumping required to lift water 1100 meters from the lowest storage point to the system’s highest point (from where gravity flow takes over) consumes a significant amount of energy, variously estimated at between 1.3 and 1.8 terawatt hours a year, equivalent to about 0.6% of Mexico’s total energy consumption, and representing a cost of about 65 million dollars/yr. This amount of electricity is claimed to be roughly equivalent to the annual energy consumption of the metropolitan area of Puebla (population 2.7 million).

The total operational costs for running the Cutzamala System are estimated at $130 million/yr. [all figures in US dollars]. Even operating at full capacity (19 m³/s or 600 million m³/yr), the approximate average cost of water would be $0.214/m³. The true costs are higher given that these calculations do not include the costs of treatment or distribution within the metropolitan area. The price charged to consumers averages about $0.20/m³.

The completion of the Cutzamala system involved resettling some villages. The plans included the construction of some 200 “social” projects to improve living conditions for the people most affected, including local potable water distribution systems, schools and roads. However, more than a decade after completion, there were still some unresolved conflicts concerning people forced to move, with many of them still claiming that they had received insufficient compensation.

Maintaining the Cutzamala system has been an on-going challenge. Most maintenance is scheduled for the Easter holiday period, when factories and offices close down and many Mexico City residents head for the beach, reducing demand for water. Since 1993, a parallel system of canals and pipelines has been built alongside the original system, allowing for sections of the old system to be shut down for maintenance, obviating the need to close the entire system whenever work is carried out.

Main sources:

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Will Mexico City add cable cars to its mass transit system?

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Apr 292013

Mexico City is one of the world’s largest cities, and the metropolitan area of Greater Mexico City (population about 22 million) extends well beyond the borders of the Federal District (Mexico City proper) into neighboring states. The city is ringed by hills. Homes have sprawled up the hillsides, often in a haphazard or unplanned way, gradually becoming established, densely-packed settlements of low cost housing, but often lacking adequate access by road for the number of people now living there. This is a particularly serious problem where settlements have been built on marginal land, in hazardous locations where the slopes are too steep or where the land is dissected by canyons. Given the terrain, it would be very expensive to improve road access sufficiently to ensure a smooth daily flow of commuters.

Unfortunately, many of these areas of the city are not reached by the city’s metro system, so the only public transport is by using microbuses, colectivos or peseros (so-called because the fare was originally one peso).

Similar cable car system in a South American city. Credit: unknown

Similar cable car system in a South American city. Credit: unknown

Earlier this year, officials from both the Federal District and the State of Mexico suggested that the answer to the transport problems of some of these marginal zones could be resolved by adding cable cars to the city’s transit system. Similar systems are already used in some cities in South America, including Medellín (Colombia).

The State of Mexico is considering installing five cable cars (teleféricos) in different parts of Greater Mexico City. The proposed system, christened “Mexicable”, would have several lines between 5 and 7 km in length. Feasibility studies for the first two lines are already underway. The first line, in the Ecatepc municipality (see map), would link San Andrés de la Cañada and la Sierra de Guadalupe, while the second line in Naucalpan would run between El Molinito and Chamapa. If approved, the state would help the municipalities concerned finance the construction of the cable car system, which would probably then be operated on a concession basis by a private operator.

The initial proposal claims that between 50 and 60 cabins, each holding 8-12 people, would leave every 12 seconds or so, allowing for the movement of up to 2800 people an hour at peak times, and up to 20,000 people each day. The system is likely to cost around $5 million (dollars) a kilometer and could be operation before the end of 2014. The government of the State of Mexico has already committed $80 million towards the preparatory studies needed for the Ecatepec cable car system.

Mexico City Metropolitan Area (Geo-Mexico Fig 22.2; all rights reserved)

Spatial growth of Mexico City Metropolitan Area (Geo-Mexico Fig 22.2; all rights reserved)

In the Federal District, a similar system, known as “Cablebús”, is being touted an an integral part of a city-wide mobility program for the next five years. The first Cablebús would run from the Sierra de Santa Catarina to Iztapalapa metro station, in the south-eastern borough (delegación) of Iztapalapa, one of the lowest-income parts of the city.

Unlike Mexico’s existing cable cars, in cities like Durango and Zacatecas, these systems are definitely aimed to serve the local people in their daily lives, and are not designed as tourist attractions. Commuting by cable car could soon become the accepted way to get to work for some residents of Mexico City, a more rapid and less-polluting alternative to existing transport options.

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Several Mexican cities rank among the American Cities of the Future

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Apr 272013

The American Cities of the Future 2013/14 rankings were published recently by the fDi Intelligence division of the U.K. Financial Times. The rankings are designed to identify the most promising destinations around the world for future inward investment.

Data were collected for 422 cities relating to more than 70 criteria, grouped into five main categories: Economic Potential, Human Resources, Cost Effectiveness, Infrastructure and Business Friendliness. Each city was awarded a score out of 10 for each criterion, with the criteria weighted by their importance to the FDI (Foreign Direct Investment) decision-making process.

  • Economic Potential eg GDP growth, Unemployment rate, Number of patents per 100,000 people
  • Human Resources eg Number of students,  Labor force with tertiary education (%), Number of international baccalaureate schools
  • Cost Effectiveness eg Rent for prime grade office space, Global grade 14 (middle manager) salary, Energy prices, Cost of establishing a business
  • Infrastructure eg Internet speed, Distance to nearest airport, Environmental performance index
  • Business Friendliness eg Number of companies in the knowledge-based sector, Corporation tax rate, Corruption perception

The top ranked city in the Americas overall (for attractiveness for inward investment) remained New York City (which attracts 1% of global FDI), followed by Sao Paulo, Toronto, Montreal and Vancouver. In Latin America, Sao Paulo was followed by Santiago (Chile), Rio de Janeiro and Buenos Aires. The top-ranked Mexican cities were Monterrey in 6th place and Mexico City which ranked #8 of the top ten.

The cities were categorized by population size:

  • Major (49 cities) – cities with a population of more than 750,000 people plus a metropolitan area of more than 2 million, or that are the center of a metropolitan area of more than 4 million.
  • Large (52 cities) – cities with a population of more than 500,000 plus a metropolitan area of more than 1 million, or the focus of a metropolitan area of more than 2 million people.
  • Mid-sized (80 cities) – cities with a population of more than 350,000 people or of more than 200,000 people plus a metropolitan area population of more than 750,000.
  • Small (196 cities) – Cities with a population of between 100,000 and 350,000.
  • Micro (43 cities) – cities with a population of fewer than 100,000.


Mexico’s cities performed very strongly in the “cost effectiveness” sub-rankings, mainly due to their favorable wage rates. The top ten in the major city cost effectiveness rankings (with rank in brackets) included Puebla (4), Guadalajara (6), Monterrey (7) and Mexico City (10). Of these four cities, only Mexico City made the top ten for Business Friendliness.

Mexico dominated the cost effectiveness rankings for large cities, taking eight of the top ten with San Luis Potosí (3), Cd. Juárez (4), Aguascalientes (5), Zapopan (6), Torreón (7), León (8), Tijuana (9) and Ecatepec (10) and did almost as well in the mid-sized cities category, with Mazatlán (5), Durango (6), Morelia (7), Tuztla Gutiérrez (8), Mérida (9) and Saltillo (10). Saltillo was the the top-performing mid-sized city for economic potential in the Americas, with strong GDP growth helping to entice investments, especially those related to vehicle parts and manufacture.

In the cost effectiveness rankings for small cities, Guaymas (2), Colima (3) and Nogales (4) all made the top ten, while in the comparable listings for micro cities, Atlacomulco (in the State of Mexico) was the number 1 ranked city in the Americas.

Apr 262013

An amendment to Mexico’s constitution in 2011 made access to potable water a basic human right, but Mexico’s major cities face unprecedented challenges in meeting future demands for drinking water. In this post we look at some of the water supply issues relating to Mexico City and Guadalajara.

In 2009, the National Water Commission (Conagua) estimated that a staggering 40% of potable water nationwide was being lost through leaks in city and municipal systems, with a further 20% not properly accounted for due to billing errors and clandestine connections. Conagua recently announced a new plan for Mexico City, that it hopes will safeguard that city’s water supply for the next 25 years. (OOSKAnews 18 April 2013)

The plan creates a new metropolitan decision-making body, which will be empowered to choose which sources of water will be used, set timelines and commitments, and monitor all activities carried out under the plan. Conagua head David Korenfeld said that establishing a single water management body for the entire metropolitan zone in the Valley of Mexico means that, “there exists no possibility of misinterpretation in collaboration”. At present, several different water management bodies have responsibility for different parts of the Metropolitan Area, which extends well beyond the boundaries of the Federal District (México D.F.) into the neighboring State of México (Estado de México).

Korenfeld argues that potable water prices must be related to the real costs of water production, system maintenance and service delivery, and that subsidies must be cut in order to achieve efficient, sustainable and equitable water management. According to Conagua data, water tariffs in the Valley of Mexico cover only  51% of the true costs of service provision.The new plan calls for the existing Cutzamala water system to be completely restructured, with an alternative channel created to bring water to the city.

sacm officeRamón Aguirre Díaz, the director of the Mexico City Water System (SACM) which would come under the new decision-making body, says that one of the main challenges is to ensure adequate water supply to the municipality of Iztapalapa. Iztapalapa is the most populous and fastest growing of the city districts, with over 90% of its territory urbanized. The SACM is suggesting a six-year, 150-million-dollar plan to resolve the situation, which would include waiving water charges for some areas where service has been poor and sporadic. Aguirre stressed the need for the government and society “to succeed in reducing water consumption and improve their habits”, saying that consumption needs to be cut by at least 30%.

Coincidentally, it is in Iztapalapa where the findings from several deep wells allowed Mexico City engineers and geologists to announce earlier this year that a 40-million-dollar study conducted over 18 months had identified a major new aquifer under Mexico City. The city has an average elevation of 2240 meters above sea level; the new aquifer, which could become a major new source of potable water, is located 2000 meters beneath the surface. The initial announcement claimed that the aquifer could supply as much as 80,000 liters of water a second.

Conagua officials cautioned that the potential usable flow of this aquifer still has to be confirmed and that it may take a further three years of research to establish the maximum sustainable yield.  The aquifer might indeed relieve Mexico City’s physical water scarcity (volumes of supply) at some point in the future, but it would not necessarily overcome the economic water scarcity (cost of supply) faced by many of its residents. (For more about economic water scarcity, see How fast is the ground sinking in Mexico City and what can be done about it?).

Frederick Mooser, arguably Mexico’s most distinguished geologist, was quoted in the press as saying that the indication of very large reserves of water below a depth of 1500 meters might well alleviate the continued need to extract water from aquifers closer to the surface, extraction that has caused so many problems for the city’s infrastructure. The major aquifer used currently lies at a depth of between 60 and 400 meters. There are about 630 wells in the Federal District alone; all are overexploited and have an average life expectancy of 30 years.

Mooser also pointed out that the results from the wells used to locate the new aquifer show that the area has considerable potential for geothermal power generation in the future.

Mexico’s second city, Guadalajara, also faces sever water management issues. According to a recent press report (OOSKAnews, 11 April 2013), Metropolitan Guadalajara loses 18% of its water through leaks in the supply system (a loss of around 41 million dollars in economic terms)

siapaAccording to an official from the city’s water utility, SIAPA, repairing ailing parts of the network (154 locations have been identified as “vulnerable”) could save most of the 4 million dollars a year currently being spent dealing with emergency repairs. However, the precise location of leaks is difficult to pinpoint because of a lack of metering equipment. In addition to the 18% lost through leaks, SIAPA believes another 12% goes unaccounted for as a result of clandestine connections and incorrect billing.

The biggest reason for leaks is the age of the system. Parts of the water supply networks in Mexico’s major cities are now over 70 years old. For example, in Guadalajara, more than 70% of the city’s 3458 km of main water supply lines is over 70 years old. Replacing the 2544 km of pipes older than 70 years would require investing around 300 million dollars, with a further 500 million dollars needed to upgrade the drainage system. SIAPA’s total investment in renewing and expanding systems is currently about 45 million dollars a year. The water firm is already said to be the most indebted decentralized public agency in the country, with debts of 240 million dollars.

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Mexico City wins 2013 Sustainable Transport Award

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Jan 192013

The Institute for Transportation and Development Policy (ITDP), together with an international committee of transportation and development experts, has awarded Mexico City the 2013 Sustainable Transport Award.

The Institute for Transportation and Development Policy works with cities worldwide to bring about sustainable transport solutions that cut greenhouse gas emissions, reduce poverty, increase urban mobility and improve the quality of urban life.

The 2013 Sustainable Transport Award recognizes Mexico City’s Bus Rapid Transit (BRT) system, cycling and walking infrastructure, parking program, and revitalization of public space. Established in 2005, the Sustainable Transport Award recognizes leadership and visionary achievements in sustainable transportation and urban livability, and is presented to a city each January for achievements in the preceding year.

Mexico City Metrobus

The Sustainable Transport Award was presented to Mexico City on January 15, 2013 at an awards ceremony during the annual meeting of the Transportation Research Board, one of six major divisions of the U.S. National Research Council. ITDP board president and former Mayor of Bogotá Enrique Peñalosa presented Mexico’s Minister of Transport, Rufino León, and Minister of Environment, Tanya Muller with the award. The former Mayor of Mexico City, Marcelo Ebrard, who oversaw much of Mexico City’s sustainable transport projects, made closing remarks at the ceremony. Janette Sadik-Khan, Commissioner of the New York City Department of Transportation, delivered the keynote address.

Mexico City has implemented many projects in 2012 that have improved livability, mobility, and quality of life for its citizens, making the Mexican Capital a best practice for Latin America.

  • The city expanded its Bus Rapid Transit system, Metrobús, with Line 4, running along a corridor from the historic center of the city to the airport.
  • The city piloted a comprehensive on-street metered parking program, EcoParq.
  • The city opened line 12 of its Metro system (Sistema de Transporte Colectivo Metro).
  • The city expanded its successful public bike system Ecobici, and added new bike routes (ciclovías).
  • The city revitalized public spaces including the Alameda Central and Plaza Tlaxcoaque.

The finalists and winner were chosen by a Committee that includes the most respected experts and organizations working internationally on sustainable transportation. The Committee includes the Institute for Transportation and Development Policy, The World Resources Institute Center for Sustainable Transport,  GIZ (Deutsche Gesellschaft für Internationale Zusammenarbeit), Clean Air Asia, Clean Air Institute, United Nations Centre for Regional Development (UNCRD), Transport Research Laboratory, EcoMobility, Local Governments for Sustainability (ICLEI) and the Transport Research Board’s Transportation in the Developing Countries Committee.

“Mexico City was like a patient sick with heart disease, its streets were some of the most congested in the world”, says Walter Hook, CEO of ITDP, “In the last year, Mexico City extended its great Metrobus BRT system straight through the narrow congested streets of its spectacular historical core, rebuilt public parks and plazas, expanded bike sharing and bike lanes, and pedestrianized streets.  With the blood flowing again, Mexico City’s urban core has been transformed from a forgotten, crime ridden neighborhood into a vital part of Mexico City’s future.”

“We congratulate the Federal District of Mexico for their leadership in advancing sustainable transport. Celebrating success is a way to highlight best practices; many cities will find inspiration in your great achievements.”

“Sustainable transport systems go hand in hand with low emissions development and livable cities. Mexico City’s success has proven that developing cities can achieve this, and we expect many Asian cities to follow suit,” says Sophie Punte, Executive Director of Clear Air Asia.

Past winners of the Sustainable Transport Award include:  Medellín, Colombia and San Francisco, United States (2012); Guangzhou, China (2011);  Ahmedabad, India (2010); New York City, USA (2009); London, UK (2008); Paris, France (2008); Guayaquil, Ecuador (2007); Seoul, South Korea (2006), and Bogotá, Colombia (2005).

[Note: This post is based on the text of a press release from the The Institute for Transportation and Development Policy (ITDP)]

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Street patterns in Mexico City

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Jan 102013

A recent post on Polis, “a collaborative blog about cities across the world”, focuses on the street patterns in Mexico City.

The post uses Google Earth images of different parts of the city to illustrate how street patterns vary between neighborhoods with different levels of wealth. This approach has long been used in urban geography, but the examples provided are a useful reminder of the value of “old-school” map interpretation skills, some of which are rapidly being lost in the age of online maps.

Mexico City Metropolitan Area: Fuentes de Aragón

Mexico City Metropolitan Area: Fuentes de Aragón

A simple exercise for students would be to ask them to choose two similar-sized cities, one in the USA and one in Mexico, and then use Google Maps and Google Earth images to compare their urban morphology (street patterns). It is worth comparing areas of different land uses (such as industrial, commercial, residential). The analysis should include some annotated images highlighting the key similarities and differences.

Mexico City Metropolitan Area (Geo-Mexico Fig 22.2; all rights reserved)

Spatial growth of Mexico City Metropolitan Area (Geo-Mexico Fig 22.2; all rights reserved)

The striking rectilinear lines usually found in poorer neighborhoods are in stark contrast to the curvilinear street patterns common in wealthier suburbs. In a city with a long history, like Mexico City, it is easy to locate and identify residential areas of very different age. (In general, the older residential areas are closer to the city center than newer residential areas.)

Mexico City: Pedregal San Angel

Mexico City: Pedregal San Angel

In the case of both Mexico City and Guadalajara (Mexico’s second largest city), a transect across the city from the wealthy west to the much poorer east will reveal remarkable differences in street patterns, corresponding closely to the patterns of wealth.

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Mexico’s changing urban landscape: the rapid rise of low-income subdivisions

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Jan 052013

Between 2000 and 2006, more than 2.3 million new low-income INFONAVIT homes were built in Mexico, a staggering rate of 2,500 new homes each and every day. The achievement was documented by photographer Livia Corona, who divides her time between New York and Mexico City, in a four-year project entitled “Two Million Homes for Mexico”. The project focuses on the “surge of mass-scale neighborhood developments in Mexico, exploring their role in the ongoing transformation of the ecological, social and cultural landscape of the nation and its citizens.”

47,547 Homes. xtapaluca, Mexico.Credit: Livia Corona.

47,547 Homes. Ixtapaluca, Mexico.Credit: Livia Corona.

As Corona’s photos reveal, while most of the “cookie-cutter” housing developments lack public amenities (schools, clinics) and public spaces (parks), and have few commercial establishments, the people moving into these homes proved remarkably adaptable and creative.

In the photographer’s own words, “Through images, films, and interviews, I look for the space between promises and their fulfillment. In my photographs of multiple developments throughout the country, I consider the rapid redefinition of Mexican “small town” life and the sudden transformation of the Mexican ecological and social landscape. These urban developments mark a profound evolution in our way of inhabiting the world.”

Credit: Livia Corona.

Credit: Livia Corona.

As she explained in an interview with Nina Corvallo for the  now-retired Nymphoto blog:

“In my current role as a visual artist, I am often familiarizing with new geographies, both for research and for commissioned assignments. My work is drawn by the underlying structures affecting quotidian survival, and my photographs expand on how these manifest on a broader level.”

“In my current work, Two Million Homes for Mexico, my drive comes from the riddle of what living in these neighborhoods can do to the development of a social and creative expression. What are the manifestations of this experience on the young minds growing up in these insular and remote landscapes, as they draw from a singular cultural and socio-economic backdrop?”

“Developers provided infinite rows of identical 100 to 200 square feet homes. Dwellers are now faced with the task of turning the rows into streets and developments into cities. I am inspired by the inventiveness of people in these neighborhoods, who are adapting with a very hands-on approach—despite a limited infrastructure—to procure a more appropriate living environment. Mexicans, as other Latin Americans, are notoriously gifted in appropriating the built environment. My project both celebrates these small individual triumphs as it frames the challenges and abuses made in providing housing for an ever-expanding population.”

The powerful images of Livia Corona are a worthy resource for urban geography classes.

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Mexico City tackles the challenges of population, commuting and air quality

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Aug 232012

This short (3 minute) video is a promotional video produced by Mexico City administrators in 2010. It refers only to the Federal District (México D.F.), and not to the entire Mexico City Metropolitan Area (which also includes parts of adjoining states).

The video highlights some of the challenges facing Mexico City’s decision makers. It uses some slick graphics to provide some of the basic facts and figures about area, population, daily commuter flows, improvements in public transportation, reductions in emissions, and so on.

Perhaps the most startling of the statistics given in the video is that the average daily travel time for Mexico City workers, including the several million who commute into the city from the surrounding states, is about three hours. This is a truly staggering amount of time compared to average commutes for most other major cities around the world.

For example, the average commute is 80 minutes a day round trip in Toronto, 68 minutes in New York, 56 minutes in Los Angeles, and 48 minutes in Barcelona. On the other hand, Moscow commuters apparently have even slower journeys to work than Mexico City residents.

World Commuting Times. © Copyright SASI Group (University of Sheffield) and Mark Newman (University of Michigan)

World Commuting Times. Click to enlarge. © Copyright SASI Group (University of Sheffield) and Mark Newman (University of Michigan); used under Creative Commons License

The size of each country on the topological map above, from Worldmapper, is proportional to the total commuting time for that country. To quote Worldmapper: “Commuting time is a measure of how long people spend travelling to work, by whatever means. It could be by foot, bus, car, boat, train, bicycle or other means. The world average commuting time is 40 minutes, oneway. This is the average for people that work.”

Total commuting time is influenced by each country’s total population, but a whole host of other factors also play a part in determining the time required for workers to travel from their place of resident to their place of work. These factors include the available means of transport, transport links, wealth, land use zoning, type of occupation, city size, and so on.

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Great new site about Mexico City’s Historic Center, but map misses the mark

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Jul 212012

A great new web portal about Mexico City’s Historic Center has just been launched by Mexico City authorities (Spanish language only at present). The portal offers hundreds of links to articles about buildings, streets, events, restaurants and almost anything you can think of relating to this vibrant heart of the capital city. In fact, the site is so interesting, I’ve just spent an entire afternoon engrossed in it!

There is one small detail on this site, however, that should not go unreported. The site’s developers have included a link to a map, vital for anyone wanting to explore this area on their own. Sadly, the file size of this map is truly massive, and will deter most users from daring to download it onto their smart phones unless they have time on their hands and an “unlimited data” plan. The map weighs in an obese 13.0 MB, quite ridiculous for what is essentially a single sheet map with no interactive functionality.

In the interests of cooperating towards a better end-product, Geo-Mexico offers its readers this smartphone-ready version, not quite as clear as the original, but sized at a much more healthy 178 KB:


Jul 192012

A short Global Post video offers a valuable, up-to-date teaching resource about Mexico City’s latest attempts to tackle air pollution, and lower carbon dioxide emissions:

The video provides an introduction to Mexico City’s “green transportation revolution”, in which electric vehicles are gradually being phased in to replace conventional taxi fleets, bicycle routes are created, modern, fuel-efficient buses extend their coverage, and biodiesel buses have been introduced along a major arterial route. The initial priority has been on the downtown area of Mexico City, the Historic Center (Centro histórico) . This 3.5-square-kilometer area receives 70,000 vehicles a day, responsible for emitting 10,000 metric tons of carbon dioxide a year. Pollution in this area has been reduced significantly in recent years. City authorities use the Historic Center as a testing ground for pollution-reduction strategies, prior to rolling them out elsewhere across the giant metropolis.

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Mexico City in colonial times: 1530–1820

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May 212012

The internal geography of cities is closely related to transportation technology. Pre-Columbian cities in Mexico were walking cities; the wheel had not been developed and animals were not used for transport. Human power moved people and goods, but not very quickly or efficiently. As a result, cities were relatively compact and congested; densities were high. Despite these transport restrictions, at least one urban center in pre-Columbian Mexico had a population estimated to exceed 200,000.

The Aztec capital Tenochtitlan was built on an island in the middle of a lake, and was a thriving city when Hernán Cortés arrived. After the conquest, the Spaniards built their colonial city directly on top of Tenochititlan’s main buildings and large central plaza or Zócalo. Spanish colonial urban centers were explicitly patterned after cities in Spain, with a grand central square or plaza at the center (large enough for displays of horsemanship). The streets were laid out following a north-south, east-west grid. In larger cities, smaller plazas might be planned every four blocks or so.

Panoramic view of Mexico City during colonial times

Panoramic view of Mexico City during colonial times. (Talavera tiles based on unattributed oil painting in the Franz Mayer Museum, Mexico City).

Colonial Mexico City conformed closely to the Latin American city model. Important government, commercial, and religious buildings, such as the Cathedral, faced onto the square. Status was largely correlated with distance from the main plaza, the hub of all activity. Wealthy and important colonial officials had large homes in a zone surrounding the main square. This zone tended to be square or rectangular given the grid pattern of streets. Less important, middle income families lived in smaller houses farther from the main plaza; lower status groups lived even farther from the main square. The lowest status mestizos and Indians lived around the outside of the city. The city was very compact and congested. The wealthiest residents in the center lived relatively close to the poorest families on the periphery. With the very high densities, there was considerable noise and congestion, as well as sanitation problems and other health issues.

As Mexico City and other major Latin American cities grew throughout the 300-year colonial period, they tended to maintain a roughly concentric pattern; however, the growth of important government and business activities as well as wealthy residential neighborhoods usually favored one side of the city.

As these high status activities expanded they slowly took over middle status areas, which in turn expanded into poorer neighborhoods. The poorest groups were pushed to the periphery or to undesirable steep hillsides or low areas prone to flooding. The rate of spatial expansion never managed to keep pace with the growth of population and economic activity. Densities and congestion increased.

From the very beginning in Mexico City, a high status sector extended west of the Zócalo. The Aztecs considered Chapultepec Hill, six kilometers (3.6 mi) west of Tenochtitlan, a royal retreat. They built a castle there, connected to their island capital by along causeway. Spanish King Charles V declared the zone a nature reserve in 1537. Early colonial Viceroys built palacial residences there. In 1592, Viceroy Luis de Velasco constructed an impressive park, the 90-hectare (216-acre) Alameda Central about a kilometer west of the Zócalo. The area between the Alameda and the Zócalo became the city’s highest status area. The development decisions made during the 16th century solidified the west as the preferred direction and set the pattern of growth for the next 400 years. Similar high status sectors evolved in virtually all Latin American colonial cities.

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Update on the activity of Popocatepetl Volcano

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May 102012

In the past few days, Popocatepetl Volcano has continued to emit gas, steam and ashes, periodically shooting ash-laden clouds high into the sky. The columns of ash have risen up to 2500 meters above the volcano before drifting downwind. Depending on the wind direction at the time, light falls of ash have been reported from Mexico City (especially the Milpa Alta and Iztapalapa districts) and the city of Puebla.

Ash cloud rises above Popocatepetl

Ash cloud rises above Popocatepetl Volcano

The National University’s Atmospheric Sciences Institute has developed atmospheric models taking account of the volcanic emissions and is releasing regular forecasts of where ash is likely to fall.

Ramón Espinasa Pereña, who heads the Geological Risks department in the National Disaster Prevention Centre (Centro Nacional de Prevención de Desastres, Cenapred) expressed concern recently that Popocatepetl Volcano could be headed towards much more significant activity in coming weeks.

In an interview with Mexico City daily Excelsior, Espinasa started by saying that that the current level of activity is less than that experienced in 2000 when the volcano’s heat caused the melting of the glacier then found on the northwest side of the mountain. However, he added, the situation today is quite different. The dome of lava inside the crater of Popocatepetl Volcano has been growing, increasing the risks of a significant and possibly explosive eruption. In 1994, prior to the 2000 eruption, the crater of the volcano was about 800 meters long, 600 meters wide and 100 meters deep. The activity in 2000 raised successive domes of lava in the crater to within 20 or 30 meters of the crater rim. So far this year, the depth of the crater has remained about the same, but only because almost all the new material being added to the existing domes is being blown into the air.

Experts are concerned that the high density of the magma beneath the volcano may lead to the existing vents being blocked. If this happens, pressure will build up underground and greatly increase the possibility of a violent eruption.

Evacuation plans have been in place since 1994, and they have been modified and updated regularly since. There are ten major evacuation routes (see map). The villages most at risk (inside the 12-kilometer radius “high risk” zone) include several in the states of Puebla (San Nicolás de los Ranchos, Santiago Xalitzintla, San Pedro Benito Juárez, San Baltazar Atlimeyaya and Tochimilco), Morelos (Ocuituco, Tetela del Volcán, Yecapixtla, Zacualpan de Amilpas and Temoac) and the State of México (Tepetlixpa, Ozumba, Atlautla, Ecatzingo and Amecameca).

Popocatepetl Volcano: the planned evacuation routes

Popocatepetl Volcano: the planned evacuation routes

Last week, the evacuation system (that will only be put into effect if the risk level rises) was tested with a large-scale practice evacuation in which the Mexican Army assisted municipal and state officials and emergency response crews. The practice has enabled authorities to improve the forecasts of precisely how long it will take to evacuate all villagers from the likely danger zone, in the event that the risk level is raised.

Evacuation will not be easy. Some local inhabitants argue that the volcano has never caused them any harm, because, on the contrary, it is their “protector and guide”. They are unlikely to move voluntarily even if an eruption is imminent. They hold a festival each year on 12 March thanking the volcano for its rich soil, abundant rainfall and “to keep the volcano calm and happy.” The ceremonies include the placing of offerings part-way up the volcano, accompanied by folk dancing.

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Apr 222012

Popocatepetl is Mexico’s second largest volcano, after El Pico de Orizaba. Popocatepetl rises to a height of 5500 meters (18,045 feet) and is located approximately mid-way between Mexico City, about 80 kilometers (50 miles) to the northwest, and the city of Puebla, a similar distance to the east.

In the past week, Popocatepetl (aka “Popo” or “Don Goyo”) has sprung back into life, blowing off steam and ash in a series of minor eruptions, accompanied by minor earth tremors, many of which registered between 3 and 4 on the Richter scale. Incandescent rocks (“volcanic bombs”) have been thrown up to 1000 meters (3000 feet) from the crater down the slopes of volcano, and water vapor, gasses and ash have formed towering clouds, up to 2000 meters high, rising above the iconic volcano.

Popocatapetl lets off steam. Credit: Victor Hugo Rojas (Universal)

Popocatepetl lets off steam. Credit: Victor Hugo Rojas (Universal)

The latest eruptions of Popocatepetl come from an estimated sixty different vents that are connected to a magma chamber 10 km (6 miles) beneath the volcano that is thought to hold upwards of 1,000,000 cubic meters (36,000,000 cubic feet) of magma. On the one hand, the small eruptions are good news, since they relieve the pressure building up underground, at least temporarily. On the other hand, they may presage a much more serious and major eruption.

Thousands of families live in the farming villages on the lower slopes of the volcano; some 25 million people live within a 100 kilometer (60 mile) radius. In the event of a major eruption, and depending on wind directions, airborne ash could fall on Mexico City, interrupting normal activities and Mexico City’s busy international airport, or on the Metropolitan area of Puebla (population 2.7 million), an important industrial center, where Volkswagen has its main vehicle factory.

Even though geophysicists are unable to say whether or when a major eruption will actually occur, authorities have raised the threat level and taken steps to ensure that local residents can be safely evacuated, if necessary, to emergency shelters in nearby public buildings such as schools. Almost 200 temporary shelters have been prepared in nearby villages to house any people that are forced to leave their homes.

Mexico’s National Disaster Prevention Centre (El Centro Nacional de Prevención de Desastres, Cenapred) has raised the alert level to “yellow stage three” – the third highest level. This level indicates that a magma expulsion is possible and that the intensity of explosions is likely to increase.

  • Access to latest CENAPRED report (in Spanish and English) English link is under “Reportes”

In the event that the alert is raised still further, into the red zone, villages within a 12-km zone will be immediately evacuated, and the exclusion zone may be extended still further if this is deemed a prudent safety measure. During the last major evacuation, in 2000, nearly 50,000 residents in three states were moved into temporary shelters.

As in the case of previous volcanic eruptions in Mexico, such as Paricutín in the 1940s, the Mexican Army would take charge of ensuring that local residents are taken to safety.

Roads are being kept open, and emergency repaving is underway, in case an evacuation is required. Local villages are arranging to have sufficient buses standing by to ensure that their residents can be evacuated rapidly should the alert level be raised. Even so, it is unlikely that everyone would choose to leave, and it is thought that up to half the population might attempt to remain in their homes even if the alert level is raised.

Images of the volcano:

Health authorities have already distributed free face masks and bottles of water to families in the area. The cloth face masks are intended to filter out the fine ash released by the volcano, and reduce the likely increase in respiratory problems. Falling ash is also expected to lead to an increased incidence of allergic conjunctivitis.

Authorities in the city of Puebla have temporarily suspended open air activities until further notice since much of the city has received a thin layer of ash. Ash falls of about one centimeter have been reported in some districts of the city. Ash has also fallen over the nearby town of Cholula and as far away as Atlixco and Huejotzingo.

Puebla hoteliers, restauranteurs and merchants will be hoping that the city’s restriction on open air activities ends quickly, since the city is gearing up for the annual festivities associated with the 5 de Mayo (5 May) festival for which the city is famous. (The festival commemorates Mexico’s victory over French forces at the Battle of Puebla on 5 May 1862).

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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.

Related posts:


Mexico City has largely escaped drug violence

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Mar 082012

Previous posts have analyzed drug war death rates in Mexican states, cities over 500,000, the most violent municipalities and areas of particular interest to expatriates. This post focuses on Mexico City or D.F. (Distrito Federal). We focus on D.F. because the rate of drug war deaths is exceptionally low there, less than one eighth the national average.

In all of 2010 there were 191 drug war deaths in D.F. [note 1] compared to 122 in the first nine months of 2011. [note 2] While this might sound like a large number of deaths, we must remember that there are almost nine million people in D.F.  The 2011 drug war death rate per 100,000/yr in D.F. was 1.8 compared to a national rate 15.3 and a rate of 134 in Acapulco. [note 3] The rate for D.F. declined 15% from the 2010 rate while the rates for all of Mexico and Acapulco increased by 13% and 187% respectively. Today, people seeking better security are moving into D.F. from other cities in the country.

Why are the rates in D.F. so low? In previous decades D.F. was thought to be one of the most violent places in the country, but this is no longer the case. The total murder rate for D.F. is half the national rate [note 4] and less than a third that of Washington, DC. [note 5] A major reason is that D.F. has a more competent, better organized, better paid and less corrupt police force than any of the other cities. The fact that the national government is in D.F. also helps as do more effective youth programs. That D.F. has higher overall income levels is also a factor. Some even speculate that major cartel bosses have family in D.F. and have an unspoken agreement to avoid violence in the capital [note 6].

The drug war death rates are quite low in all parts of the city. The wealthy delegation of Cuajimalpa in western D.F. had zero deaths in 2011 compared to 11 a year earlier. In 2010 it had the city’s highest rate of 5.9, but this was still less than half the national average. Relatively sparsely populated Milpa Alta in the southeast also had zero deaths in 2011. Cuauhtemoc and Venustiano Carranza, two central delegations, had the highest rates in 2011, but they both less than a third the national average.

The 13 suburban municipalities adjacent to D.F. in the State of Mexico experienced 331 drug war deaths in 2011, almost three times the number in D.F. These suburbs with a total population of just over six million had a combined drug war death rate of 7.3, four times as high as D.F. While the death rate in these municipalities increased 42% over the 2010 level, it was still less than half the national average. Based on the data presented above, it is not surprising that people worried about drug violence would rather live in or near D.F. than in most other cities, especially those in northern and western Mexico.

  1. “Mexican drugs war murders data mapped”, The Guardian, posted by Johanna Tuckman, Jan 14, 2011. For data see:
  2. “Van mas de 47 mil muertos por nacroviolencia: PGR”, El Universal, 12 January 2012,
  3. The rates for 2011 were adjusted because data are available for only the first nine months of the year.
  4. “Is Mexico City safe from drug cartel war – or the next target,” CNN, January 17, 2012, .
  5. “Mexico’s violence not as widespread as seems,” USAToday, 3 August 2010.
  6. Is Mexico City safe from drug cartel war — or the next target,” CNN, January 17, 2012, .

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…

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 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

The urgent need for reforestation of hills near Mexico City

 Mexico's geography in the Press  Comments Off on The urgent need for reforestation of hills near Mexico City
Jan 172012

A coniferous tree plantation is being formed on the lower slopes of Ajusco, the 3,930 m (12,894 ft) volcanic peak that overlooks the southern part of Mexico City. After decades of uncontrolled land clearance, local farmers are replanting 800,000 trees as part of a sustainable project which will ensure them a reliable income for years to come. Mexico’s National Forest Commission estimates that mature coniferous plantations are highly profitable, and should repay farmers a 500% return on their investment. Individual trees have to be at least 8 years old before they can be harvested.

Three species of conifers are being planted: the Sacred Fir (oyamel), Douglas Fir and Mexican White Pine (ayacahuite). At present, only about one-third of Christmas trees sold in Mexico are natural trees, with 60% of these having to be imported from as far away as Canada.

The project will not only increase farmers’ incomes, it will also reduce soil erosion, increase carbon storage, and bring hydrological benefits. Mexico City has seriously depleted its aquifers – see Why are some parts of Mexico City sinking into the old lakebed? Reforesting the hills surrounding the city means more water will be retained in the soil, and less will runoff into the city’s already-stressed network of storm drains.

Ajusco is not the only volcanic peak near Mexico City where deforestation has become a major issue. In August 2011, National Water Commission (Conagua) officials blamed serious flooding in the Rayón municipality of the State of México on the uncontrolled logging of the lower slopes of the Nevada de Toluca volcano.

The lack of protective forest cover meant that heavy rain caused the River Santiaguito to burst its banks and flood homes in the community of San Juan La Isla. The situation would have been far worse if Conagua had not ordered the dredging of 12,000 cubic meters along a 4 km stretch of the river bed in 2009. Following the 2011 floods, Conagua reiterated the need for more reforestation and called for stricter land use controls to prevent similar problems in the future.


Traffic congestion still a serious problem for commuters in Mexico City

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Sep 242011

An IBM survey of 8,042 commuters in 20 cities on six continents shows that more people are now taking public transport rather than driving. In general, people report that traffic has improved over the past three years.

The survey, entitled Global Commuter Pain, found that commuting in Mexico City was the “most painful” of the 20 cities studied; commuting in Montreal, Canada, was the “least painful”. The survey suggests that infrastructure investments in congested cities are repaid with improved travel times. Mexico City’s investments in public transport over the next few years should help move it away from the bottom place in the rankings.

Mexico City traffic

"Welcome to Mexico City"

Two-thirds of drivers in Mexico City said they had decided not to make a driving trip at least once in the last month due to anticipated traffic conditions. Asked about the longest amount of time they had been stuck in traffic over the past three years, the mean time reported by Mexico City drivers was over two hours. (Drivers in Moscow fared even worse, with 30% reporting delays over three hours).

The index is comprised of 10 issues: 1) commuting time, 2) time stuck in traffic, agreement that: 3) price of gas is already too high, 4) traffic has gotten worse, 5) start-stop traffic is a problem, 6) driving causes stress, 7) driving causes anger, 8) traffic affects work, 9) traffic so bad driving stopped, and 10) decided not to make trip due to traffic.

The cities scored as follows: Mexico City: 108; Shenzhen 95; Beijing 95; Nairobi 88; Johannesburg 83; Bangalore 75; New Delhi 72; Moscow 65; Milan 53; Singapore 44; Buenos Aires 42; Los Angeles 34; Paris 31; Madrid 28; New York City 28; Toronto 27; Stockholm 26; Chicago 25; London 23; and Montreal 21.

  • The IBM report on the 2011 Commuter Pain Survey (pdf file).

Mexico D.F. administration offers amnesty to illegal water users

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Jul 202011

According to a recent report in Ooska News (8 June 2011), Mexico City authorities have announced an amnesty for people who regularize illegal water connections. No fines will be levied, and they will be encouraged to pay only 600 dollars (a 50% discount) for registering connections and connecting to the waste water drainage network.

There are believed to be at least 250,000 illegal connections in Mexico D.F. Legislators hope that about half of these will take advantage of the amnesty program.

In the neighboring State of México, the National Association of Water and Sanitation (ANEAS) estimates that 60% of water connections in that area are also  illegal. ANEAS claims that 38% of all water in Mexico is lost through leaks in supply systems, including domestic connections, and a further 20% is lost because of illegal connections.

Related posts:

More problems for residents of Valle de Chalco on the south-eastern edge of Mexico City

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May 112011

More than 200 homes in the low-income settlement of Valle de Chalco on the south-eastern edge of Mexico City, in the State of México, were flooded by raw sewage last month. The affected homes were in San Isidro and La Providencia, in Valle de Chalco (see map).

Mexico City cracks map
Locations in Valley of Mexico with high incidence of ground cracks. Cartography: Tony Burton; all rights reserved.

At least 500 residents faced a grim clean-up following several days of flooding. The problem was caused by a 30-meter-long crack in a surface sewage canal known as the Canal de la Compañia. The crack allowed 6,000 cubic meters a second of raw sewage to inundate nearby streets and homes. The federal water authority, Conagua, said that it would take three weeks to complete repairs to the canal wall.

Canal de la Compañia, Chimalhuacán

Canal de la Compañia, Chimalhuacán

The canal wall is thought to have been put under too much pressure due to the unfortunate combination of unusually heavy rains and a blockage occasioned by accumulated garbage such as plastic bags. It is possible that continued ground settling –More ground cracks appearing in Mexico City and the Valley of Mexico – also contributed to the problem. José Luis Luege Tamargo, the head of Conagua, placed much of the blame for the most recent flooding on the local municipal authorities of Ixtapaluca for not having ensured that no garbage was dumped anywhere in or near the Canal.

The 260 families and small businesses affected were all given some immediate financial assistance via 20,000-peso payment cards valid at any Soriano supermarket. In addition, authorities have pumped out basements and begun an emergency vaccination campaign.

The Canal de la Comañia’s walls have failed three times in the past decade, with serious flooding each time; the most recent disaster was in February 2010, when 18,000 people were forced to flee the rising wastewater. Conagua has reportedly proposed a more permanent remedy involving the rerouting of 7 km (almost 5 miles) of canal. The project would take two years to complete, with an estimated cost of 300 million pesos ($25 million).

The on-going transformation of Mexico City

 Mexico's geography in the Press  Comments Off on The on-going transformation of Mexico City
May 082011

A feature article in (link below) summarizes some of the reasons behind our long-held view that Mexico City has started, and is still undergoing, a noteworthy transformation. Change is happening not only in the urban fabric but in many aspects of the daily lives of “capitalinos“, the most polite of the various  terms used in Mexico for residents of Mexico City.

Map of Mexico City urban system

Map of Mexico City urban system. Click to enlarge. All rights reserved.

We will continue to offer occasional updates on the transformation taking place in Mexico City in future posts. Previous posts on this blog have examined many different aspects of Mexico City’s on-going transformation:

Mexico’s cities and towns are analyzed in chapters 21, 22 and 23 of Geo-Mexico: the geography and dynamics of modern Mexico. Buy your copy today!!

Attempts to provide drainage for Mexico City date back to Aztec times

 Excerpts from Geo-Mexico, Mexico's geography in the Press  Comments Off on Attempts to provide drainage for Mexico City date back to Aztec times
Apr 262011

An old joke relates how engineers initially rejoiced at successfully draining the former lake on which Mexico City was built (something the Aztecs had tried, but failed to achieve), only to discover that the city now lacked any reliable source of fresh water for its inhabitants (something the Aztecs had successfully managed by building a system of aqueducts).

Water has been a major issue for Mexico City since it was founded almost 700 years ago. Civil engineering works by the Aztecs included causeways and aqueducts connecting their island capital to the mainland as well as lengthy dikes separating the fresh water lakes from the brackish Lake Texcoco which surrounded the city.

The Spaniards did not maintain the Aztec civil works, deforested the surrounding hillsides, and started filling Lake Texcoco. This contributed to major flooding in 1555, 1580, 1604. The city was actually underwater (continuously!) from 1629–1634. During this period the Spaniards invested in several flood control efforts, but they were not successful. In 1788 they started construction of a massive canal to connect the basin to rivers north of the city flowing to the Gulf of Mexico. The open canal, which was up to 30 m (100 ft) deep in places, provided flood relief, but did not completely solve the problem, and flooding continued.

In the mid-1850s the government approved another massive flood relief scheme. Construction of the Gran Canal was delayed by numerous political and financial problems; it was not completed until 1900. The 58 km (36 mi) long canal included a 10 km tunnel, and carried lake water, storm water and sewage north to the Río Salado and eventually to the Gulf of Mexico. The scheme successfully drained most of the basin lakes, but summer flooding continued to be a problem for decades.

Mexico’s deep drainage system (drenaje profundo) was completed in the 1970s. It relies on a 68-km-long central tunnel (Emisor Central) which has a maximum depth of 250 meters below the surface. Built to allow for a flow of 170 cubic meters/second, subsurface subsidence under Mexico City had reduced its maximum capacity to barely 15 cubic meters/second by 2008.

Paradoxically for a city originally built on a lake and which experiences regular summer floods, Mexico City is desperately short of drinking water. The drilling of wells to obtain potable water from the aquifer under Mexico City is one of the main reasons for the ground subsidence which has reduced the effectiveness of the deep drainage system.

Many parts of Mexico City still experience serious drainage problems every rainy season. During the long dry season, many street drains plug with garbage (especially impermeable plastic bags). City motorists dread the first heavy rains of the year since much of the rainwater which falls is unable to find its way underground and backs up from blocked drains. City authorities have an annual campaign to try to clear all drains before the first rains, but are never completely successful.

Since 2007, jointly agreed programs to maintain and renovate the deep drainage system have been undertaken each year during the dry season by Mexico City and the administrations of adjoining states, in an effort to reduce the metropolitan area’s serious flood hazard. In the first four years (2007-2010), more than 42 km of tunnels have been renovated. The 2010-11 season of repairs to the drenaje profundo will be completed before the start of the rainy season (usually in late May or early June), according to city mayor Marcelo Ebrard.

Why are some parts of Mexico City sinking into the old lakebed?