Flooding in Mexico City during the rainy season is as inevitable as the rain itself but despite efforts for centuries to deal with the issue, a forever-growing population means the problem persists.
Already parts of Mexico City have been inundated this season — the rains fall from May/June through to October — despite the near-daily rains having only just begun.
Forty-one neighborhoods located mainly in southern boroughs of the city were affected after heavy rainfall Monday night.
To understand why flooding is still a problem that afflicts Mexico City today, it is necessary to go back to Aztec times.
According to a study by National Autonomous University professor Dr. Ramón Domínguez Mora, the main cause of flooding in the city was in trying to solve the problem at the time it occurred but without “putting a brake on the growth of the city.”
Tenochtitlan, the city that became Mexico City, was originally built on an island in Lake Texcoco but as the need arose for more land to accommodate a growing population, the lake was drained and filled in.
But an adequate drainage system was not established, wrote Domínguez Mora, and when it rains the water tends to accumulate rather than be absorbed into the earth because of the city’s topography.
It wasn’t until 1604, when the city was the capital of New Spain and part of the Spanish crown’s vast overseas empire, that the first efforts were made to drain excess rainwater.
In response to flooding, dikes were built to divert the rain. However the project took almost two centuries to complete and it turned out not to be a long-term solution.
Consequently, in 1866 construction began on the Gran Canal de Desagüe, a 39.5-kilometer drainage canal that was finished in 1900.
At the time it was thought that it would put an end to the flooding, the researcher wrote, but a rapidly growing urban population made it difficult for that infrastructure to cope as well, and by the 1940s the problem of flooding had returned.
Again new infrastructure was needed and a deep drainage system was built, beginning operation in 1975.
The 164-kilometer deep system functions for the removal of wastewater and rain in the metropolitan area of Mexico City and its conurbation.
However, once again it failed to keep up with an incessantly growing population.
But it is not just the sheer number of people and the consequent increase of domestic water use that causes flooding to occur.
According to data from Inegi, the National Statistics Agency, every resident in Mexico City produces on average 770 grams of trash a day and inevitably a portion of that is not disposed of correctly.
When the rains come, trash lying in the capital’s streets is swept towards an already vulnerable drainage system, blocking storm drains and preventing the water from being carried away.
According to the Mexico City government, half of all flooding in the city can be attributed to this factor and is most prevalent in poorer parts of the city, which often have inferior infrastructure compared to more affluent areas.
Still, the problem cannot be solved by education and improved trash disposal alone.
Adequate infrastructure plays a vital role in the ongoing containment of the problem as well and the National Water Commission (Conagua) is currently working on six drainage tunnels. It says they will further “mitigate the risks of flooding in the Valley of México.”
Source: Tec Review (sp)