Swim at your peril through the murky data for Mexico’s beaches

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May 062013

In the past few months, it has become harder than ever to assess the cleanliness of Mexico’s beaches. Alejandro Calvillo, director of the consumer rights organization “El Poder del Consumidor” recently published an alarming blog post alleging that Mexican authorities have gone to considerable lengths in recent months to mask the true state of Mexico’s contaminated beaches. (Playas contaminadas en México, un secreto de Estado)

Drain on Mocambo Beach, Veracruz. Credit: La Voz del Sureste.

Drain on Mocambo Beach, Veracruz. Credit: La Voz del Sureste.

Calvillo explains that for several years, government agencies published regular monthly statistics relating to the cleanliness of all the country’s major swimming beaches. While some people queried the veracity of some figures, at least the data was publicly available, and provided some starting point for analysis and discussion. Indeed, this data allowed us to write in Geo-Mexico (p 46) that,

“Coastal waters are also regularly monitored for contamination. The percentage of Mexico’s resort beaches that met national water quality norms rose from 93.7% in 2003 (when 226 beaches in 35 destinations were tested) to 98.4% in 2007 (276 beaches in 46 destinations). Seawater at all coastal resorts is now well within the national standard except for Ixtapa-Zihuatanejo on the Guerrero coast.”

However, soon after the new administration (of president Enrique Peña Nieto) took office, Calvillo claims that a decision was made to cease releasing regular monthly data for beach contamination and to remove the historical time series of beach cleanliness data from government internet sites (such as those of the Health Secretariat and Environment Secretariat). Fortunately, Calvillo’s claims are not the whole truth. Data are still being published for many beaches, via an interactive webpage titled Playas Limpias (Clean Beaches) hosted by the Health Secretariat. However, it does appear to be true that the historical series of pre-2013 data have vanished, and that no data is available, even in 2013, for several beaches that were previously regularly monitored.

There is no doubt that in recent years hundreds of Mexican beaches have on occasion had excessive levels of Enterrococos faecalis, the main bacteriological indicator. (About a decade ago, counts of Enterococcus spp. replaced fecal coliform counts as the best way to assess the water quality at public salt water beaches.) The major source of contamination, despite years of campaigning by environmental groups, comes from hotels, towns and cities that continue to dispose of their effluent directly into the sea, often in close proximity to popular swimming beaches (see photo). Progress has been made in some states, including Jalisco, Nayarit and Veracruz, but there is still a long way to go.

water quality on beaches

Water quality on Mexican beaches, 2011. Source: Atlas Digital del Agua México 2012;
(green=good; yellow=moderate; red=poor)

Calvillo writes that official reports in 2011 (see map) listed 99 beaches where Enterococus levels had been found in excess of 200 Enterococci/100 ml of water on at least one occasion. Values over 200 Enterococci/100 ml are considered to pose a “health risk”, according to Mexican norms. Of these 99 beaches, 70 were on the Pacific coast. The worst beaches included 1 in Baja California Sur (La Paz), 4 in Nayarit (including Sayulita, Rincón de Guayabitos), 3 in Jalisco (including Playa del Cuale in Puerto Vallarta), 10 in Michoacán (including Caleta de Campos, Chuquapan and Playa Nexpa) and 3 in Guerrero. In the worst locations, the Enterococci count was over 20,000/100 ml.

Of the 29 beaches with excessive values on the Gulf of Mexico and on the Caribbean coast, the most polluted were on the Gulf of Mexico, including locations in Tamaulipas, Veracruz and Campeche.

In summer 2012, the 22 beaches that posed a health risk according to the data included Regatas (Veracruz), Rincón de Guayabitos (Nayarit) and Playa Carabali (aka Playa Hornos) in Acapulco (Guerrero).

Despite having made less data available for 2013, in the days leading up to the 2013 Easter vacation period, federal and state government officials repeatedly stressed that all beaches were clean and ready to receive the anticipated hordes of holidaymakers. It is difficult to assess the accuracy of these claims in the absence of more data. Were the beaches really clean, or were tourists in some destinations risking potentially serious gastrointestinal and other diseases every time they went swimming?

Adding another layer of complexity to interpreting the statistics is the fact that several states have massaged the data tables by selectively changing the names of some beaches, and omitting others. For example, Calvillo points out that in 2011 the state government of Veracruz renamed four beaches that had previously experienced high pollution levels so that their historical records would be hard to find:

  • Costa de Oro I became Gaviota II
  • Iguana Norte was renamed Tortuga II
  • Iguana Sur became Pelícano II
  • Penacho del Indio was renamed Pelícano I.

In 2012 Veracruz removed two beaches from its list completely: Iguana Centro and Acuario, which it deemed “no longer of interest to tourists,” perhaps because its 2009 count was a record-breaking 159,490 Enteroccocus/100 ml.

Veracruz is not the only state to have “tweaked” its data. Jalisco decided (in 2009) not to monitor either Conchas Chinas or Boca de Tomatlán, both of which had registered high levels of contamination in previous years. In the state of Guerrero, the main beach in Zihuatanejo (historically one of the most polluted beaches) has not been monitored since 2011 because of “technical problems”. [Note: Measurements began again here in 2013, at about the time this post was first published.]

The moral of this post? The absence of data for any particular beach should not be taken as indicating that it is not contaminated. On the contrary, the absence of data might perhaps better be interpreted as a sure sign that the beach HAS or MIGHT HAVE a problem!

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What is the elevation of Mexico’s cities?

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Feb 042013

The short answer to “What is the elevation of Mexico’s cities?” is “somewhere between zero and 3000 meters (8200 ft) above sea level!” Mexico’s extraordinarily varied relief provides settlement opportunities at a very wide range of elevations. Many Mexican cities are at or near sea level. This group includes not only coastal resort cities such as Acapulco, Cancún and Puerto Vallarta, but also Tijuana on the northern border and, at the opposite end of the country, Mérida, the inland capital of Yucatán state.

Mexico City, the nation’s capital, has an average elevation of about 2250 meters (7400 ft.), similar to that of nearby Puebla. Toluca, the capital city of the state of México, is almost 400 m higher, while both Huixquilucan and Zinacantepec (also in the state of México) are at an elevation of over 2700 meters. Moving northwards from Mexico City, numerous major cities are at elevations of between 1500 meters and 1850 meters above sea level. The cities nearer the lower end of this range include Saltillo, Oaxaca and Guadalajara, while Aguascalientes, Querétaro, Guanajuato, Morelia and León are all situated at elevations close to 1800 meters.

Frequency plot of city elevations in Mexico. Credit: Geo-Mexico

Frequency plot of city elevations in Mexico. Credit: Geo-Mexico

Are there more cities at some elevations than others? Each dot on the graph above represents one of Mexico’s 170 largest cities and towns, plotted against its average elevation. The two major clusters of cities occur at elevations of close to sea level and at 2250 meters, with another smaller, more spread out cluster between 1500 meters and 2000 meters. Perhaps somewhat surprisingly, there are relatively few Mexican cities at elevations of between 100 and 1500 meters (4920 ft.).

  • Q. Can you suggest any reasons for this? [Hint: Look at a relief map of Mexico to see how much land surface there actually is at different elevations].

The graph also shows the division of Mexico’s climate and vegetation zones by elevation first proposed by Alexander von Humbuldt following his visit to Mexico in 1803–1804. The terms tierra caliente, tierra templada, and tierra fría are still widely used by non-specialists today to describe the vertical differentiation of Mexico’s climatic and vegetation zones (see cross-section below).

Altitude zones

Altitude zones. Copyright John Wiley & Sons Inc. 2000.

The tierra caliente (hot land) includes all areas under about 900 m (3000 ft). These areas generally have a mean annual temperature above 25°C (77°F). Their natural vegetation is usually either tropical evergreen or tropical deciduous forest. Farms produce tropical crops such as sugar-cane, cacao and bananas. Tierra templada (temperate land) describes the area between 900 and 1800 m (3000 to 6000 ft) where mean annual temperatures are usually between about 18°C and 25°C (64°F to 77°F). The natural vegetation in these zones is temperate forest, such as oak and pine-oak forest. Farms grow crops such as corn (maize), beans, squash, wheat and coffee. Tierra fria (cold land) is over 1800 m (6000 ft) where mean annual temperatures are in the range 13°–18°C (55°–64°F). At these altitudes pine and pine-fir forests are common. Farm crops include barley and potatoes. On the highest mountain tops, above the tierra fría is tierra helada, frosty land.

Interestingly, the tierra templada appears to have fewer cities than might be expected. Equally, while archaeologists have sometimes argued for the advantages of siting settlements close to the transition zone between climates, where a variety of produce from very distinct climates might be traded, the graph shows no evidence for this.

It would be misleading to read too much into this superficial analysis of the elevations of Mexican settlements. First, we have only considered the 170 largest settlements. Second, an individual settlement may extend over a range of elevation, so using an average figure does not reveal the entire picture. Thirdly, the precise elevations for tierra caliente, templada and fria all depend on the latitude and other local factors. Even so, it might be interesting to extend this analysis at some future time to include far more settlements to see if the patterns identified are still present or if others emerge.

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The geography of road transport in Mexico

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Oct 202011

Mexico’s road network is heavily used, accounting for over 95% of all domestic travel.  On a per person basis, Mexicans travel an average of 4500 km (2800 mi) by road each year.

In this post, we try to answer several general questions relating to the geography of road transport in Mexico.

How many cars are there?

On average there are about seven people per car in Mexico, compared to about six in Argentina, ten in Chile and less than two in the USA and Canada. There are far more cars in urban areas with their many businesses, taxis and wealthy residents. In poor rural parts of southern Mexico, private car ownership is quite rare.

Is there an efficient bus system?

Mexico also has an inter-city bus system that is one of the finest in the world. The nation’s fleet of more than 70,000 inter-city buses enables passengers to amass almost half a trillion passenger-km per year.

Where are Mexico’s vehicles made?

Almost all the vehicles on Mexico’s roads were built in Mexico. Mexico’s automobile-manufacturing sector produces about 2.2 million vehicles a year but the majority of production (about 1.8 million vehicles each year) is for export markets. Mexico is the world’s 9th largest vehicle maker and 6th largest vehicle exporter. In recent years, the relaxation of strict import regulations has resulted in more vehicles being imported into Mexico; many of them are luxury models not currently made in Mexico.

The major international vehicle manufacturers with plants in Mexico include Volkswagen, Ford, Nissan, GM, Renault, Toyota and Mercedes-Benz. Mexican companies include Mastretta, which specializes in sports cars, and DINA, a manufacturer of trucks, buses and coaches.

For more information about vehicle manufacturing in Mexico:

Where are Mexico’s vehicles?

Mexico has about 20 million registered vehicles, about one for every five persons (2005). Which areas have the most and least vehicles? It turns out that the northernmost state, Baja California, has the most with 37 registered vehicles per 100 people. The southernmost states, Chiapas and Oaxaca, have about one sixth as many with 6.6 and 6.9 respectively. In fact there is a very strong statistical relationship between latitude and vehicles (see graph). How can this be?

Scattergraph of latitude and vehicle registrationsWe are not suggesting a direct causal relationship. Many factors are interrelated. First, the states in the north tend to be wealthier; the Spearman rank correlation for GDP/person and latitude is 0.58. Vehicle ownership is closely related to GDP/person (rs = 0.59). Both these correlations are significant at the 99% level.

In addition, northern states are close to the USA, a vehicle-oriented society. However, there are some anomalies to the general pattern. The very wealthy Federal District has 50% more vehicles than would be expected from its latitude alone. States with many migrants, such as Jalisco and Michoacán, also have more vehicles than expected given their latitude. An added complication is that more than a million foreign-plated cars in Mexico (imported temporarily by returning migrants or foreigners) are not included in these figures.

How many road accidents are there in Mexico?

Mexico’s National Council for Accident Prevention estimates that there are 4 million highway accidents each year in Mexico. The latest figures (for 2010) show that there were 24,000 fatalities as a result of these accidents, with 40,000 survivors suffering some lasting incapacity. These figures include some of the 5,000 pedestrians struck by vehicles each year. Traffic accidents are currently the leading cause of death for those aged 5-35 in Mexico, and the second cause of permanent injury for all ages.

Why are there so many accidents?

Driver education plays a major role in road safety. Part of Mexico’s problem is the low budget it allocates each year for road safety—just US$0.40 compared to more than $3.00/person in the USA, more than $7.00/person in Canada and up to $40.00/person in some European countries.

It is no surprise that a high percentage of drivers involved in traffic accidents in Mexico have alcohol in their system. This is one of the reasons why accidents are statistically more frequent in the evenings from Thursday to Saturday. One study reported that as many as 1 in 3 of drivers in Guadalajara was under the influence of alcohol while driving, and 1 in 5 of Mexico City drivers.

Driving without insurance is common in Mexico; according to insurance companies, only 26.5% of Mexico’s 30.9 million vehicles have any insurance.

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Is tourism in Mexico expanding?

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Sep 112010

At first sight, this would seem like an easy question to answer but, in fact, it is not exactly clear whether tourism in Mexico in 2010 is increasing, decreasing or holding steady. Flows of tourists are affected not only by any changes in the situation of the destinations (receiving countries) but also by the situation at the point of origin. Most of Mexico’s international visitors come from the USA. This year, many potential tourists have opted to stay at home as a result of the current recession which started in 2008 and worsened in 2009.  On the other hand, the recession may have diverted some tourists to Mexico from more expensive destinations they had originally planned to visit.

Cruise ship

Events within Mexico have also influenced the number of international tourist arrivals. The threat of H1N1 flu in early 2009 kept many international tourists away. Publicity about the violence associated with Mexico’s “drug wars” has accelerated in 2010 and almost certainly diverted some international tourists to other destinations.  On the other hand, some tourists who planned their 2010 summer vacation on the US Gulf Coast may have opted for Mexico after the massive oil spill off Louisiana.  An additional complicating factor is that international tourists only account for about 20% of Mexico’s total tourism revenue. While international tourism gets most of the attention, about 80% of tourism revenues come from national (Mexican) tourists.

Statistical data on tourism can be very difficult to interpret. The World Tourism Organization (WTO) and Mexican tourism agencies use similar international definitions of  a tourist:

  • A tourist as someone who spends at least one night (and less than one year) away from their usual home.

This definition ignores the precise reasons for travel. Hence, international tourism figures generally include travel for all purposes, including visiting family and friends, and business trips, as well as health and religious travel.  All these factors make assessing trends in Mexican tourism an analytical challenge.

In an August 2010 press conference, Mexico’s Secretary of Tourism Gloria Guevara presented data indicating that 818,278 international travelers visited Mexico in the month of June 2010 compared to only 605,435 in June 2009. This increase of 24% seems impressive, but requires closer scrutiny.  International arrivals in January and February 2010 were 5.2% and 5.8% less respectively than the same months in 2009; revenues for those two months were up 21% in peso terms, but actually fell by 7.5% in dollar terms, because of the falling value of the peso. Arrivals in March 2010 were 2.7% higher than March 2009.

Room occupancy rates (the percentage of available hotel rooms actually occupied) in 70 tourist destinations were up 11% for the first six months of 2010 compared to the same period in 2009.  However, 2009 was a very poor year for tourism in Mexico. Only 21.5 million international travelers visited Mexico in 2009, compared to a record 22.6 million in 2008.

Another major complication to the statistics is that they mask important regional differences. Tourism in some areas of Mexico is increasing steadily while it is simultaneously declining in others.  For example, occupancy rates for the first six months of 2010 were up 30% in Morelia and 15% in Huatulco compared to the previous year. However 14 of the 70 cities monitored showed no gain in occupancy over the low numbers posted in 2009. All these percentage figures ignore any changes in hotel capacity over that time. For instance, if an additional 2000 hotel rooms are opened in a resort, the occupancy rate may decrease slightly, even though more tourists actually visited the resort.

For cruise ships, a similar picture emerges. Though cruise ship visitors to Mexico were up in the first six months of 2010, they remain lower than the 2008 numbers for the equivalent period.

So, is tourism expanding, or not? Overall, tourism in 2010 is certainly improving over the 2009 numbers, which is quite encouraging given the extremely negative publicity resulting from drug war violence.  However, it is too early to say if the total number of visitors and revenues in 2010 will surpass the numbers for 2008.  This will depend not only on publicity related to Mexico’s fight against drugs, but also on the speed and extent of economic recovery in the USA. In addition, the collapse of Mexicana airline means that there are currently far fewer flights into Mexico that there were at this time last year.

See also:

Chapter 19 of Geo-Mexico: the geography and dynamics of modern Mexico focuses on Mexican tourism and development.  Buy your copy today to have a handy reference guide to all major aspects of Mexico’s geography!