river restoration in mexico city

4th ECRR Conference on River Restoration Italy, Venice S. Servolo Island 16-21 June 2008

MEXICO CITY: FROM WATER AVENUES TO ASPHALT RIVERS

Current condition and future perspectives of the Mexico City Rivers

Perló M.*, González A., Zamora I., Hernández L.

University Program on City Studies, National Autonomous University of Mexico *Corresponding author, e-mail: [email protected]

ABSTRACT

Mexico City developed in a hydrological basin where was formed a natural lake system. This situation made the city vulnerable to floods caused by its overflowing lakes. Thus, Mexico City and its relation to its lacustrine environment have been conflictive ever since the Spaniards conquered the city in the Sixteen Century, and through our present day and age. Successive generations over four centuries built hydraulic works that aimed to empty the basin’s lakes through different tunnels. The war against water has characterized this city over the centuries. Once the Valley of Mexico dried up in the Twentieth Century, the city’s growing population polluted its rivers and the best solution consisted of confining the waters to pipes and transforming their beds into vehicular roadways.

In this present day and age, all recovery or rehabilitation of a urban Mexico City river demands taking its hydraulic history into account; that history structured the huge drainage system that collects and expels lake water from the basin, as well as the rivers confined in pipes, and the city’s rain and wastewater. The rescue of an urban Mexico City river is faced with the challenge of overcoming the prevailing cultural and technological inertia.

We entered the Twenty-first Century with the idea of shifting paradigms and recovering an urban river on the southwestern side of Mexico City. This project intends to amend the historically conflictive relationship that has existed between water and the capital city's residents, and thus start to support sustainability in one of the world’s largest cities. Keywords: Mexico City, hydraulic history; draining lakes, rivers confinement; river rehabilitation.

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Mexico City: from water avenues to asphalt rivers

1. INTRODUCTION. MEXICO CITY AND WATER: A GREAT PARADOX

The Mexico basin was a natural endorreic basin, that is to say, a closed basin in a valley with a vast system of lakes formations, but it has become an artificially open and semi-deserted basin. The Mexico Basin has been exploited by successive generations that succeeded in drastically modifying its hydrological operation over the last four centuries.

The war against flooding has been a constant since the city of Tenochtitlan was founded and in the current Mexico City metropolitan area. This constant battle waged against the excess of water over the centuries, derived in a great paradox in the Twentieth Century: while Mexico City succeeded in overcoming its flood and full outlet nightmares, the valley lacked enough water to meet the growing demand of its explosive urbanization. We must bear in mind that Mexico City went from having two to 20 million inhabitants in just six decades. In principle, the efficient expulsion of land and rain waters from the Valley of Mexico allowed for urban and industrial development of the metropolis through the extraction of underground water sources. However, once these underground sources were found to be insufficient in the 1940s, city authorities built an aqueduct to import water from a neighboring basin. Later on, in the 1980s, the city built a second aqueduct to transfer water from another neighboring basin. These two aqueducts (the Lerma and Cutzamala systems) supply approximately 30% of the potable water that Mexico City requires.

Rivers did not represent a possible water supply solution for the city throughout the Twentieth Century. On the contrary, their status as seasonal rivers and polluted by the cities that were incorporated into the capital city’s metropolitan area, caused these to be perceived as a health hazard for the population. The solution to the problem consisted of laying pipes to confine and discharge the contaminated waters and rebuild the structures left by their old channels to transform them into avenues for vehicular transportation purposes. Hence, the different drainage works caused rivers to be classified as wastewater. The city condemned the rivers to a murky death: their mild water currents were reduced by concrete and asphalt.

The present is charged with history. Any project to rescue the urban rivers within this context demands a full understanding of the long-term processes that have had an impact on hydraulic history in the Mexico City Valley, the cultural history of the type of urbanization and its relation with the environment. The rescue of an urban river in Mexico City represents a serious challenge that is limited not only to technology and methodologies, but is affected primarily by historical, social and cultural factors.

Perló M., González A., Zamora I., Hernández L.

2. FROM AN AMERICAN VENICE TO A THIRSTY MEGALOPOLIS

The Mexico Basin consolidated itself as an endorreic formation on the geological horizon of the Tertiary; that is to say, close to 9,600 square kilometers were hydrologically enclosed to house lake lowlands 2,250 meters above sea level. Five lakes were then formed and trapped among mountains and hills that became one great lake during the rainy season. The lakes known as the Zumpango and Xaltocan lakes flowed on the north side of the city; while the Xochimilco and Chalco flowed on the southern side of the Valley, each at a different altitude, but each intercommunicated as they flowed into the Texcoco River at the center of the valley. The lakes were fed by the runoffs that flowed from the high areas through torrential rivers and the summertime rain and precipitation that ranges between 1500 mm and 600 mm. The rivers were between one and five meters deep and covered between 1500 and 2000 square kilometers, close to one-fifth of the total surface of the basin.

The Mexica civilization faced cyclical floods that decimated its population. Nonetheless, the solutions propounded to face these catastrophes never questioned the cultural strategy of leveraging the benefits the lakes provided. The construction in 1449 of a huge 16-kilometer stone dyke to protect the Greater Tenochtitlan from the curse of the floods is attributed to Netzahualcoyotl, king of Texcoco. This dyke was built to keep the overflowing Zumpango and Texcoco lakes.

Once the Europeans conquered the Mexico City Valley, they modified the mentalities and the practices regarding the ecosystem. The complex lacustrine life became a problem for the Spaniard’s conception of a city. The viceregal capital was founded over the ruins of Tenochtitlan and faced the water’s destructive from its very creation. The chronicles report floods of great magnitudes in 1555, 1580, 1604 and 1607. The New Spain policy with respect to the valley’s water did not contemplate its retention, rather the radical modification of the Valley’s ecosystem. The city’s first ambitious project to artificially discharge the waters of the Cuauhtitlán River through a tunnel drilled in the northern part of the basin was completed in 1608. This first artificial solution is known as the Tajo de Nochistongo (Nochistongo Tagus). This hydraulic work in the Seventeenth Century set off a strategy that is maintained through this day and age to expel the lakes and rivers from the Mexico Basin. The Nochistongo Tagus protected the viceregal capital from floods that originated from the rivers and lakes from the north of the valley; however, it could not protect it from the floods originating from the east, south and center of the valley.

In the Nineteenth Century, General Porfirio Díaz undertook a second drilling process to drain the basin in the year 1900 in the Tequixquiac Mountain; however, flooding continued during the first half of the Twentieth


Century, flooding the downtown area of the modern capital city for weeks at a time. The revolutionary government built a third artificial drainage system close to 200 meters from the previous system in 1947 and the fourth drainage system, the largest one to date, was finally initiated in 1975, which consists of a 200-meter deep tunnel that flowed into the El Salto River; and thanks to these four artificial drainage systems, the Mexico City Valley is no longer a closed basin, as it started to discharge its overland waters from 1607 to date, into the neighboring Tula River basins, which carries the water to the Gulf of Mexico.

After draining the five lakes of the Mexico Basin for three-and-one-half centuries, the landscape has been drastically modified and the superficial waters started to become scarce and be in short supply. The subterranean aquifers of the valley itself solved urban development early on in the Twentieth Century, but this alternative reached its limit when it started to sink the subsoil in downtown Mexico City. The excessive extraction of underground water caused the clay in the subsoil to compact and start to cave in. It was then that engineers in the revolutionary state designed and built the first infrastructure to bring water from a neighboring basin: the Lerma System that initially collected the springs from the Almoloya River and later on extracted water from the subsoil of the Toluca and Ixtlahuaca valleys. However, the city’s explosive demographic growth in three decades caused the imported water from the neighboring basin to be insufficient. Thus, a second system was inaugurated in 1982 with the same objective: “import” superficial waters collected in dams at the Cutzamala River Basin, over 100 kilometers away from the capital city, overcoming a 1,000 meter difference in elevation. 3. URBAN MODERNITY AND RIVERS CONFINEMENT

The use of rivers was never an option for the modern Mexico City, as people in the 1930s perceived the streams and rivers as discontinuous and hard to control: “The streams that feed the Federal District flow in from the surrounding mountains; most are classified as torrential waters and of a passing nature. They include the Consulado, Los Remedios, Tlalnepantla, Churubusco, and the Piedad rivers, although none of these are important streams and some overflow and flood portions of the surrounding land at certain times of the year." (DDF, 1930:18).

As the rivers flooded the new suburbs, the governement started to apply a policy that consisted of containing them through a system of dams in the west of the city. The solution was to collect the waters in small dams and create underground tunnels to bring them north through drainage systems, remove them from the city and finally expel them from the basin. The Mixcoac dam was built between 1937 and 1941, and the Mixcoac-Becerra


tunnel was built between 1937 and 1940. The Tacubaya dam was built between 1936 and 1938, and the Tacubaya-Tecamachalco tunnel was built between 1935 and 1937. The San Joaquín dam was built between 1935 and 1936, and the San Joaquín-Tornillo dam was constructed was built between 1936 and 1938. In summary, during the thirties, the transformation of the social representation of the rivers was consolidated, which changed from viewing them as a local source of water and peripheral irrigation, to viewing them as responsible for floods and sources of infection.

Despite all the protective hydraulic works, Mexico City continued to suffer from severe flooding during the 1940s. A second wave of confining the rivers was then undertaken, beginning with the Viga Canal that was enclosed in 1941. A portion (10.4 kilometers) of the Consulado River was then piped between 1944 and 1960, as the river was not very bountiful and was seasonal and its borders has been settled by human settlements that constantly felt threatened by its overflowing and by the fact that it transported large amounts of wastewaters from the capital city’s thriving industry. People held negative perceptions of the Consulado River, and most others by stating that, “These channels, which frequently overflow in times of heavy rainfalls cause dangerous floods in large areas; they are also unhealthy centers because they do not have a continuous current flows, they are dry most of the year and encouraged the accumulation of trash and all kinds of filth. The greatest damage was caused by the Consulado Rivers, which flowed through populated colonies [neighborhoods] such as Cuauhtémoc, San Rafael, Santa Julia, and Santa Maria, Nonoalco, Peralvillo, Vallejo and numerous other neighborhoods to the East.” (DDF, 1942:113). Communication between the Santa Maria, San Jacinto and Tacuba colonies improved once the river was confined to pipes (DDF, 1975), and a new layer of asphalt was laid over its bed by creating a paradigmatic solution to the new river urbanization strategy.

Pictures 1 and 2 – Magdalena river confined in 1960

A portion –11.3 kilometers of the Piedad River was piped between 1945

and 1960, in parallel with the construction of the network of collectors and


improved drainage systems, representing a long process that included a variety of different public works. A portion (21 kilometers) of the Churubusco River was confined between 1950 and 1975.

Urban development used the riverbeds as borders between different neighborhoods, and the construction of highways, thus resolving automobile trip needs. The modern city model involved the design of large avenues to connect the different regions of the capital city; thus another 1.9 km of the Piedad River were piped between 1947 and 1957, to connect the Becerra River and the Miguel Alemán Viaduct and create an expressway to drive from the east to the western side of the city. During this same period, the city piped 542 meters of the San Joaquín River and thus the rivers were gradually transformed into the mute asphalt avenues of the city.

In the fifties, the city’s government and residents continued to fight their rivers and in 1951, the waters of the Churubusco River were diverted to the National Canal to maintain the decreasing water levels of the Xochimilco, Tláhuac and Mixquic Lakes. In 1953, the Los Remedios River overflowed and flooded several surrounding colonies. The first floods in the fifties were clear proof that the drainage repairs were insufficient, as certain areas of the city started to cave in. The solution had to be generalized and in 1953, the Head Office of the Federal District’s Hydraulic Works Department introduced the “General Plan to resolve the sinking and flooding problems in Mexico City and supply running water in Mexico City.” The plan permanently modified the riverbeds that ran through the capital city and finished piping of the Consulado River and the close to 80 kilometers that remained of the Churubusco, Magdalena, San Angel, Mixcoac, La Piedad, Becerra, Tacubaya, Dolores, Barrilaco, and the Tecamachalco and San Joaquín Rivers. The works were completed with the construction of the so-called Western Interceptor that was built to collect the waste and rain waters. The interceptor was 17 kilometers long and divided the Magdalena River, running through the Chapultepec hills until it poured into the Remedios River (Casasola, 1967:2908).

Work was started on the Grand Channel in 1960, which would help carry waters from the rivers that were now combined and undivided from wastewaters generated by the different neighborhoods. The Grand Channel was built to flow down the Hondo River and into the Vaso de Cristo River. Between 1963 and 1964, the Western Interceptor was extended to the Cuauhtitlán River, the Zumpango Lake and the Nochistongo Tagus. The Western Interceptor opened an outlet for the rivers to flow to the western and southwestern sides of the city, which represented a health and aesthetic problem for the subdivisions and colonies, which also allowed for the waters to flow and drain towards the north.


Figure 1 – Urban rivers and urban development in Mexico city Between 1960 and 1970, a good part of the north and northeast of Mexico

City was industrialized, leading to explosive population growth, which grew to nine million citizens in 1960, and 14 million residents by the eighties, which caused a rapid growth in metropolitanization. The needs and services had to correspond to the modern dimensions of the large city and its population in such a manner that the authorities decided to create a Deep Drainage system. The sewer system was modernized during its construction, and the river problem was finally resolved and controlled to improve the city’s “roadway, sanitary and aesthetic aspects". This system confined: 620 meters of the San Juan de Dios River, 1.7 kilometers of the Miramontes Canal, 200 meters of the San Buena Ventura River, 1 kilometer of the Tacubaya River, 1.3 kilometers of the Hondo River, 1.6 kilometers of the San Angel River and 300 meters of the Barranca del Muerto River and also dredged part of the endless Churubusco River, piping it up to Zaragoza (DDF, 1975:231).


4. REHABILITATING THE MAGDALENA RIVER AGAINST THE HISTORIC INERTIA THAT PREVAILS IN THE MEXICO BASIN

The sanitary hydraulic paradigm was conclusive in its results and one can now affirm that all of the rivers in the Mexico Basin are fragmented by dams, artificial derivations and other types of hydraulic works. It is important to note that some rivers of the east of the basin still run their natural course, they are approved for local agricultural activities and flow into the remainder of the Texcoco Lake.

People have raised their voices within this context with a clamor to change the handling and management of the river basins by building an alternate model that demonstrates the benefits of incorporating a river into the urban environment. These types of proposals have been concentrated to rescue the Magdalena River found in the southwestern side of the city.

There are several reasons that play a role in choosing the Magdalena River to create a new paradigm: the excellent quality of the water found in its upper portion, the eminently young forest and conservation of the natural area, its entrance with an open riverbed to the urban area, its contributions to the water supply (210 L/s) and its historical heritage and cultural relationship with the city. Thanks to this great natural and socio-cultural potential, the Magdalena River persists in the social imagination as a possibility for changing the course of the hydrological history of our city. Articulation of the project among civil, academic and government parties finally allowed the different forces to organize to restore the river by drawing up a Master Plan.

The Master Plan for the Comprehensive Management and Sustainable Use of the Magdalena River Basin has been in process since November 2007 and is expected to be announced to the population in the summer of this year. The Plan has a multipurpose focus that will promote the eco-systemic services this river provides for the city and will create a cultural, social and urban development with the river as the centerpiece of one of the largest linear parks in Latin America.

Pictures 3 and 4 – Magdalena river in Mexico city


Finally, with the drying up of the lakes and the piping of the central rivers of the city, the Magdalena River does not have a natural outflow to a larger body of water. First of all, the water goes partially through the Western Interceptor and the water that continues its natural course flows into the Churubusco River, which is fully piped and carries only wastewater.

The outlook reflects several issues, one of which we would like to discuss at this time: does the Magdalena River have the characteristics that are needed for restoration purposes or can it only be rehabilitated? The plan’s progress allows us to rely on the elements that are needed to respond to the previous questions. There are probably no city rivers that have the characteristics that are needed to ensure their restoration, when we consider the concept of restoration as the return of a system to its natural and original conditions (Society for Ecological Restoration: 1994). The advanced polluted conditions and the hydraulic intervention of the rivers in the Mexico Basin do not allow for its restoration, at least not in a primary phase. On the other hand, the Plan can pursue the objective of recovering certain basic biophysical elements of the ecosystem, especially in the urban area as well as the forest gallery and from the soil on the river banks, which are suit the classic notion of rehabilitating an urban river (Findlay & Taylor: 2006).

If this plan were to succeed in a short-term harmonization of the results derived from an integral vision for the long-term, we will be able to reflect on the relationship we have kept with our rivers. Instead of considering them as a threat and a weakness in our surroundings, we will be able to convert transform them into spaces that offer multiple environmental, social, cultural and economic opportunities.

5. CONCLUSIONS

Mexico City can be considered as a metropolis that overpoweringly transformed its urban rivers into vehicular roadways, driven by a vision for progress and modernization. In 40 years, the city erased close to 83 kilometers of rivers, which is three times the size of the largest avenue in the world (Insurgentes located in Mexico City).

Mexico City’s present day challenge consists of redirecting the relationship between our society and the environment. Hydric sustainability implies changes in the manner in which we formulate the problem itself: it is no longer a matter of trying to dominate nature to our own benefit; that is to say, this no longer has to do with bringing water from far regions or mixing rain water with wastewater and expelling it to even more remote sites; neither is it a matter of confining the rivers that still flow under the open skies, to pipe flows. From hereon after, the problem’s formulation is not based exclusively on the construction of dikes, dams, aqueducts and channels; that is to say, this is not a matter that is exclusive to civil and hydraulic engineering. The Twenty-First Century is now faced with the


challenge of taking action on our own selves; on the need for society to regulate itself to its own benefit, as the protection and efficient management of hydric resources –and environmental resources, in general– will guarantee its future viability.

This is a huge challenge and we are now driven by a new vision to beat it. We expect to change the manner in which we have related to our rivers through the city’s sustainability and the future of the 51 rivers that still remain in the basin and refuse to disappear.

ACKNOWLEDGMENTS

Thanks to Professor Miguel Segundo. REFERENCES Casasola, G. (1967) Historia gráfica de la Revolución Mexicana 1900-1960, Trillas,

México. DDF (1930) - Atlas general del Distrito Federal, Talleres Gráficos de la Nación,

México, 340pp. DDF (1942) - Memoria del Departamento del Distrito Federal (1° de septiembre de

1941 al 31 de agosto de 1942), DDF, México, 282pp. DDF (1975) – Memoria de las obras del sistema de drenaje profundo del Distrito

Federal, Tomo II, DDF, México, 237pp. Ezcurra, Ezequiel, et. al. (2006) La cuenca de México, FCE, México, 286pp. Findlay, S. & Taylor, M (2006) – Why rehabilitate urban river systems? Area, 38

(3), 312-325. Herrera, I. & Dumars, Ch. (1995, Eds.) El Agua y la ciudad de México, Academia

de la Investigación Científica, México, 353pp. Musset, A. (1991) – De l’eau vive à l’eau morte. Enjeux techniques et culturels dans

la vallée de Mexico (XVI-XIX siècles), Editions Recherche sur les Civilisations, Paris, 321pp.

Perló, M. (1989) – Historia de las obras, planes y problemas hidráulicos en el Distrito Federal, 1880-1987, Universidad Nacional Autónoma de México, México, 118pp.

Perló, M. & González, A. (2005) - ¿Guerra por el agua en el Valle de México? Estudio sobre las relaciones hidráulicas entre el Distrito Federal y el Estado de México, PUEC-UNAM & Fundación Friedich Ebert, México, 144pp.

Perló, M., González, A., Zamora, I., (2008) - Definiciones básicas y principios rectores para el Plan Maestro del río Magdalena, reporte de investigación, Programa Universitario de Estudios sobre la Ciudad, México, 20pp.

Postel, S. & Richter, B. (2004) - Rivers for life, Island Press, California, 240pp. Riley, A. (1998) – Restoring streams in cities, Island Press, Washington D.C., 423

pp. Stanton, P. (2007, Eds) - Rivertown. Rethinking urban rivers, The MIT Press,

Cambrigde, Massachusetts, 215pp.

river restoration in mexico city

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