Apr 252016
 

Cuatro Ciénegas (“Four Marshes”) is a city and municipality in the northern border state of Coahuila. Founded in 1800, it has some historical significance, since it was the birthplace of Venustiano Carranza, Mexico’s president from 1915 to 1920.

The natural nearby “marshes” are highly unusual. Situated in an arid region (part of the Chihuahuan desert), they include several natural springs that feed more than 200 small ponds and wetlands. Some of the water supporting these unique wetlands, which cover an area of 84,400 hectares, is believed to be more than 200 million years old. The wetlands are an integral part of the UNESCO-designated Cuatro Ciénegas biosphere reserve. The reserve is home to several endemic organisms, including microorganisms such as cyanobacteria that historically helped produce oxygen for the Earth’s atmosphere. The area is considered “a living laboratory of evolution and the origin of life”.

Cuatro Ciénegas. Credit: Nancy T. Wilson (MexConnect)

Cuatro Ciénegas. Credit: Nancy T. Wilson (MexConnect.com)

Human activities in the surrounding area have led to severe water stress on the Cuatro Ciénegas marshes. The basin’s average natural recharge rate (replenishment rate) is about  25 million cubic meters a year, but the average yearly extraction rate, almost all for agricultural use, is close to 49 million cubic meters.

Water stress may be exacerbated in coming years by climate change, which may reduce rainfall while simultaneously increasing evapotranspiration.

Scientists have also identified five particular exotic (introduced) species that pose a significant risk to the long-term quality of the Cuatro Ciénegas wetlands. Whether naturally or deliberately introduced, these five species – African jewelfish, blue tilapia, giant cane (giant reed), Guatemalan fir and tamarisk (salt cedar) – threaten to displace endemic species and change natural nutrient flows and food chains. Guatemalan fir and tamarisk soak up water as they grow, further drying out the marshes (though, eventually, when little water is left, they will die off). The blue tilapia carries parasites that can jump to local species that have no resistance to them. The African jewelfish occupies the same ecological niche as the endemic mojarra and gradually replaces it.

Mexico’s Comision Nacional de Áreas Naturales Protegidas (CONAMP), is now working with the Mexican Fund for Nature Conservation (FNCN) and the Canadian government agency Parks Canada to develop and implement a control and eradication program to tackle these five invasive species. The long-term survival of this highly unusual ecosystem may well depend on this program’s success.

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The Aqueduct of Padre Tembleque is Mexico’s 33rd UNESCO World Heritage Site

 Mexico's geography in the Press  Comments Off on The Aqueduct of Padre Tembleque is Mexico’s 33rd UNESCO World Heritage Site
Nov 102015
 

Earlier this year, UNESCO added a 16th century aqueduct in Mexico to its list of world heritage sites, bringing the total number of such sites in Mexico to 33.

The Aqueduct of Padre Tembleque was constructed between 1554 and 1571. It is named for the Franciscan friar, Francisco de Tembleque, who began the 48-kilometer-long aqueduct, which was built to transport water from what is now Zempoala, Hidalgo, to Otumba in the State of México. The aqueduct connects to an engineered water catchment area, springs, canals and distribution tanks.

Location of Aqueduct of Padre Tembleque

Location of Aqueduct of Padre Tembleque (Source: Google Maps)

The aqueduct was built with support from the local indigenous communities: “This hydraulic system is an example of the exchange of influences between the European tradition of Roman hydraulics and traditional Mesoamerican construction techniques, including the use of adobe.” (UNESCO)

Aqueduct of Padre Tembleque

Aqueduct of Padre Tembleque (Credit: Xinhua/INAH/NOTIMEX)

While much of the aqueduct is at ground level or underground, it crosses over the Papalote River near Santiago Tepeyahualco supported by a graceful series of high arches called the Main Arcade, 67 arches in total, and at one point 39 meters above the river (the highest single-level arcade ever built in an aqueduct “from Roman times until the middle of the 16th century.”)

The Aqueduct of Padre Tembleque is the largest single hydraulic engineering project completed in the Americas during Spanish colonial times and is a worthy addition to the World Heritage list.

For more information:

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More water meters for Mexico City

 Mexico's geography in the Press, Updates to Geo-Mexico  Comments Off on More water meters for Mexico City
Oct 122015
 

A recent OOSKAnews report says that Mexico City’s water authority (Sacmex) is seeking to purchase 27,835 more water meters that it plans to install in coming months. Sacmex supplies water to around 2 million separate addresses, of which 1.4 million are already metered. The latest purchase is part of Sacmex’s plan to ensure that 100% of connections to the water system are metered. Sacmex’s current budget includes $3.5 million for an additional 40,000 meters.

sacmex

At present, users without a meter pay a fixed bi-monthly tariff based on the building category, and intended type of water use (domestic/industrial/commercial).

Funding for the meters will be part of a $200 million World Bank-supported “Program to Improve the Efficiency of Operating Organizations” (PROME) which has already financed various projects across the country for urban areas with populations over 20,000. Projects already funded by the Progam include more efficient pumps, the updating of user databases with geo-referencing technology, and studies to gauge the robustness of indicators such as water pressure, water quality and leak detection.

Sacmex is also working on other distribution issues. Earlier this year – see Water in Mexico: a human right that is currently subsidized and wasted – Sacmex CEO Ramón Aguirre Diaz said that the agency required $430 million to combat leakages in the system (currently estimated at around 40% of supply), and claimed that a long-term program to fix the problem would be introduced next year.

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Water in Mexico: a human right that is currently subsidized and wasted

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Aug 172015
 

Two recent articles in OOSKAnews, a publication dedicated to news in the water industry, have profound implications for Mexico’s water supply situation. The first (10 July 2015) is a report of a meeting in Guanajuato of national water and water treatment specialists (Segundo Encuentro Nacional de Áreas Técnicas  de las Empresas de Agua y Saneamiento de México).

Selected quotes from the report include,

Mexico’s legal framework for water is out of date and does not reflect the country’s current reality…

Nationwide, water users only pay about 20% of the cost of production; 80% of water costs are subsidized, a situation that is not sustainable…

Legal reforms aimed at protecting human rights with regard to water had harmed service providers, who cannot cut off service to customers who fail to pay their bills.”

The report also comments on the on-going El Zapotillo dam project on the Rio Verde in Jalisco state, saying that it,

is a priority for President Enrique Pena Nieto’s administration, despite ongoing delays and legal conflicts. The $1.24 billion dollar project was approved in 2005 and is more than 80% complete. However, residents of Temacapulín, Acasico and Palmarejo have been fighting construction of the dam, which would flood their villages.”

sacmex

The second report focuses on Mexico City and the estimate by Ramón Aguirre Díaz, the head of Mexico City’s Water System (SACMEX), that fixing leaks in the city’s potable water distribution network would cost around US$430 million. This is a huge cost when compared to the system’s annual budget for maintenance and improvement of infrastructure of about US$135 million.

Aguirre claims that 40% of available water is lost because of leaks in the network. SACMEX is launching a program in 2016 to provide a long-term solution to the problem. In a press interview, the official said that, “A city like ours should be able to supply every citizen by producing 26 cubic meters/second, but currently our system requires 30.5 cubic meters/second”.

The sections of the city with the most severe losses are those like Coyoacán and Tlalpan built on the soft sediments of the former lake-bed, as well as those such as Miguel Hidalgo, Cuauhtémoc, and Benito Juárez, where the supply pipes are more than 70 years old. Combined, these areas house over 2.5 million people.

Aguirre also outlined the progress made in bringing reliable access to potable water to all 1.8 million inhabitants of Iztapalapa, one of the poorest and most densely populated sections of the city. Some 72,000 residents in Iztapalapa lack piped water supply to their homes, and therefore have to depend on provision from tanker trucks. Even those who do have access to piped water have to cope with inadequate pressure, poor water quality and frequent supply outages.

According to Aguirre, the city administration will meet its goal of reliable access to piped water for all of Iztapalapa by 2018. Reaching this point requires the construction of 22 water treatment plants and various other major infrastructure modernization projects.

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Mexico City’s Drinking Water Fountains

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Aug 102015
 

Earlier this summer, Mexico City’s Water System (SACMEX) inaugurated a network of 230 drinking fountains installed in public spaces across the city. The fountains are part of the city’s initiative to curb reliance on bottled water. (Mexicans consume more bottled water per person than any other country in the world).

water-fountains-mexico-city

Click for interactive map of Mexico City water fountains

The sites for the fountains were selected taking local water quality into account. An interactive website enables residents and visitors alike to find the locations of the fountains, and offers up-to-date information about the water quality parameters.

water-quality-xochimilco-july-2015.

Sample water quality report – Xochimilco, July 2015 [Click to enlarge]

Water from all the fountains is being tested on a regular basis to ensure that it complies fully with official water quality standards.

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Ground subsidence in Mexican cities

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May 112015
 

The sinking of parts of Mexico City into the former lake bed on which much of it is built is well documented, but to what extent does subsidence also affect other Mexican cities?

Estell Chaussard and her co-authors considered this question in their article entitled “Magnitude and extent of land subsidence in central Mexico revealed by regional InSAR ALOS time-series survey.” Subsidence, often resulting from over-depletion of ground water, has a range of human impacts, including decreased supply of safe water, an increase in flood risk, and a greater hazard threat from building or street failure.

In their time-series analysis of more than 600 Synthetic Aperture Radar (InSAR) images of central Mexico, the authors found evidence of significant subsidence in seventeen cities, including sixteen cities with a population of 100,000 inhabitants or more. The cities affected (with their population in parentheses) are listed here from east to west:

  • Puebla (2,500,000)
  • Mexico City (21,000,000)
  • Toluca (427,000)
  • Querétaro (825,000)
  • San Luis de la Paz (101,000)
  • Celaya (266,000)
  • San Luis Potosí (936,000)
  • Morelia (537,000)
  • Salamanca (144,000)
  • Irapuato (317,000)
  • Silao (147,000)
  • León (1,400,000)
  • Aguascalientes (735,000)
  • Zamora (186,000)
  • Guadalajara (3,800,000)
  • Ahuacatlán (6,500)
  • Tepic (261,000)

Their analysis suggested that the rates of subsidence over a two-year period were nearly constant at most locations, typically between 5 and 10 cm/yr. (In contrast, subsidence in Mexico City was around 30 cm/yr, in line with previous studies.)

ground-fissures

Ground failure by groundwater withdrawal subsidence. Credit: Natural Science, Vol. 6, No 3, 2014.

An earlier study – Subsidence risk due to groundwater extraction in urban areas using fractal analysis of satellite images – had found that the intense groundwater pumping regime in Irapuato for urban supply and agriculture (the area is one of Mexico’s main strawberry-growing centers) had resulted in 18 subsidence fault systems with a total length of 27 km, causing damages to more than 200 houses.

Meanwhile, previous work in nearby Celaya – Subsidence in Celaya, Guanajuato, Central Mexico: implications for groundwater extraction and the neotectonic regime – found that subsidence in that city was due to a complex combination of factors, and not entirely due to excessive groundwater extraction. Most earth fissures in the Celaya area were related to pre-existing structural features, and the authors suggested that thermal springs also appeared to play a role.

References:

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Ground subsidence in Mexico City threatens 10,000 homes

 Mexico's geography in the Press  Comments Off on Ground subsidence in Mexico City threatens 10,000 homes
Feb 052015
 

The local authorities in Iztapalapa, in the eastern section of the Mexico City Metropolitan Area, and one of the most interesting locations in Mexico in which to witness Easter celebrations, calculate that around 10,000 homes are in the area are at “high risk” of serious damage due to ground subsidence. Some parts of the city are falling in elevation as the ground contracts by up to 40 cm/yr.

Low-lying Iztapalapa is one of the most densely populated parts of the city, and is also prone to frequent flooding. Experts say that the severe damage evident in many buildings in the area has been occasioned by ground subsidence, due to the excessive volumes of water being pumped out of the subsoil to satisfy the insatiable demand of Mexico City.

In a short 3-minute news video in Spanish that is linked to in this recent article, Lourdes, a local resident offers us a tour of her home, showing us the damages caused by subsidence. She describes how “the crack that started from outside the house has widened every day and is now almost the width of a hand.” The video shows how the walls of her home are separating; the house is clearly in danger of collapse. Lourdes lives in this house with her four children; some rooms are already far too damaged to be safely used by the family.

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Access to safe water is a human right in Mexico

 Mexico's geography in the Press  Comments Off on Access to safe water is a human right in Mexico
Dec 132014
 

Earlier this year, David Korenfeld, the director of Mexico’s National Water Commission (Conagua), was chosen to head the inter-governmental council that oversees UNESCO’s International Hydrological Program (IHP). The IHP is the only inter-governmental program of the U.N. system devoted to water research, water-resources management, and education and capacity building.

In his acceptance speech, Korenfeld called for “greater synergy between decision makers and specialists to combine theory and practice” and stated that “significant challenges remain [in the water sector], including integral basin management, application of the human right to water and water security and sustainability in the context of climate change.

Recent events demonstrate that Mexican courts are happy to uphold the view that water is a basic human right. The 5 Dec 2014 issue of the OOSKAnews, a newsletter dedicated to water industry professionals, included the following short piece about a landmark recent decision by Mexico’s Supreme Court that represents the first ever Supreme Court decision in Mexico upholding the nation’s stance that “water is a basic human right.”

The Supreme Court has for the first time awarded an “amparo” (similar to an injunction, a remedy for the protection of constitutional rights), based on the human right to water.

In this case, members of the court unanimously sided with Lidia Velázquez Reynoso, a resident of the Ampliación Tres de Mayo area in the municipality of Xochitepec, in the state of Morelos.

In their ruling, the court said authorities must meet their obligation to provide Velázquez’s residence with “access, availability, and sanitation of water for personal and domestic consumption in a sufficient, safe, acceptable, and affordable form.” A lower court had already ruled in favor of Velázquez, but the case was appealed.

The Supreme Court said responsible authorities had failed to guaranteed regular delivery of water, since merely connecting Velázquez’s residence to the water system was not good enough. Water quality and volume must also be taken into account. The court said that the water must meet World Health Organization standards, and the volume provided must be at least 50 to 100 liters per person per day.

The court ordered authorities to not only deliver the water to Velázquez, but also to remit records showing that the water meets national and international standards.

(OOSKAnews, 5 December 2014)

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How does Mexico’s water footprint compare to that of other countries?

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Oct 292014
 

In a previous post, we saw how Mexico is a major net importer of “virtual” water. In this post we take a closer look at Mexico’s water footprint. The data throughout this post come from The Water footprint of Mexico in the context of North America (pdf file).

Individual products each have their own water footprint in terms of the total amount of water involved in their production, processing and marketing. For example a single cup of coffee represents (on average) a water footprint of 140 liters. Other water footprints include:

  • A single letter-sized sheet of paper – 10 liters
  • Microchip – 32 liters
  • Pair of leather shoes – 8000 liters
  • Glass of milk 200 liters
  • Glass of wine 120 liters
  • Tomato 13 liters
  • Hamburger (150 gram) 2400 liters

From numbers like these, it is possible to calculate the water footprint for an individual consumer in a particular country, and also for an average consumer in each country.

How does the water footprint in Mexico compare to other countries?

The water footprint of Mexico (WWF 2012)

The water footprint of Mexico (WWF 2012)

The graphic shows that Mexico’s total water footprint (all consumers) is 197,425 Hm³, of which 92% is agricultural, 3% industrial and 5% domestic. Only 57% of Mexico’s water footprint is internal, the remaining 43% is external (ie water used in other countries to make or produce items imported into Mexico). The average water footprint per person in Mexico comes to 5419 liters/day (or 1978 m³/year).

The global average water footprint (all countries, all consumers) in 2010 was 1,385 m³/y. However, some countries have much higher average water footprint/persons than others. For example, the average consumer in the USA has a water footprint of 2,842 m³/y, whereas in China and India the average water footprints are 1,071 and 1,089 m³/y respectively.

The water footprint of an average consumer worldwide  is primarily determined by their consumption of cereal products (contributes 27% to the average water footprint), followed by meat (22%) and milk products (7%).

It should be remembered that countries which heavily rely on foreign water resources may have significant impacts on water consumption and pollution elsewhere.

Full report:

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Mexico is a major net importer of “virtual” water

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Oct 132014
 

The concept of “virtual water” was developed by Professor J.A. Allan of King’s College (London University) and the School of Oriental and African Studies. Allan used it to support his argument that Middle Eastern countries could save their scarce water resources by relying more on food imports. The idea was sufficiently novel for Allan to be awarded the 2008 Stockholm Water Prize.

In Allan’s words, “The water is said to be virtual because once the wheat is grown, the real water used to grow it is no longer actually contained in the wheat. The concept of virtual water helps us realize how much water is needed to produce different goods and services. In semi-arid and arid areas, knowing the virtual water value of a good or service can be useful towards determining how best to use the scarce water available.”

As one example, producing a single kilogram of wheat requires (on average) around 1.5 cubic meters of water, with the precise volume depending on climatic conditions and farming techniques. The amount of water required to grow or make a product is known as the “water footprint” of the product.

Hoekstra and Chapagain have defined the virtual-water content of a product, commodity, good or service, as “the volume of freshwater used to produce the product, measured at the place where the product was actually produced”. The virtual water content is the sum of the water used in the various steps of the production chain.

Additional examples, showing the water footprint of producing one kilogram of:

  • biodiesel from soya –  11.4 cubic meters
  • beef –  15.4 cubic meters
  • butter –  5.5 cubic meters
  • chocolate – 17.0 cubic meters
  • pasta –  1.85 cubic meters
  • sugar (from cane) –  0.2 cubic meters

While the idea of virtual water has attracted some attention, its methodology is contested, and its quantification is not yet sufficiently precise to offer much potential for policy decisions.

Imports and exports of virtual water represent the “hidden” flows of water involved when food and other commodities are traded from one place to another. The map below (from Hoekstra and Mekonnen, 2012) shows the net imports (imports minus exports) of virtual water for different countries for the decade 1996-2005. Note that only the major flows are shown.

water-virtual-tradeIn North America, both the USA and Canada have a significant positive virtual water balance (i.e. they are major exporters of virtual water), whereas Mexico has a significant negative water balance, and is clearly one of the world’s largest importers of virtual water.

As Allan’s original work suggests, this is not necessarily bad news since it may imply that Mexico is currently using less of its own (limited) water resources than it might otherwise have to. In other words, Mexico’s virtual water imports may be delaying the inevitable crunch time when water usage becomes a critical limiting factor in the nation’s development.

Source of map

A.Y. Hoekstra and M.M. Mekonnen. 2012. The water footprint of humanity. Proc. Nat. Academy of Sciences, 109, 3232-7. Map was reproduced in “Spotlight on virtual water” by Stuart N. Lane in Geography, vol 99-1, Spring 2014, 51-3.

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