5 siglos de crecimiento de la zona metropolitana del Valle de México...

De este artículo extraemos la siguiente imagen, que habla por sí sola:

Fuente: Are mega cities viable? By: Ezcurra, Exequiel, Mazari-Hiriart, Marisa, Environment, 00139157, Jan/Feb96, Vol. 38, Issue 1

La descripción del artículo:

This article describes the poor environmental and living conditions in Mexico City due to its huge size. Mexico City's size is a challenge to sustainability, and the outcome is unknown. Mexico City and the geographic basin surrounding it included about 18.5 million population in 1995. The basin and surrounding volcanic ranges include nine major environmental zones. Urban growth followed four stages. Different cultures applied different solutions to water supply problems. The basin shifted from self-sufficiency to reliance on 31% of supplies from external watersheds. The water table is declining and canals are polluted. Irrigated agriculture is disappearing. There is an average water deficit of over 800 million cubic meters per year. Mexico City is actually sinking due to groundwater exploitation. There is bacterial contamination of wells due to improper seals. About 75% of the population has access to wastewater treatment and sanitation, but sewage treatment plants operate at under 50% efficiency and treat only about 7% of the total wastewater. Atmospheric pollution from suspended particles has been a problem for decades. Ozone was the most significant air contaminant in 1994. Lead was the most harmful pollutant in 1986. Air pollutants may be the source of submucosal inflammations. Industrial areas are contaminated with suspended particles and sulfur dioxide. High traffic areas have high carbon monoxide levels. Atmospheric pollution has affected the quality of the rainwater. The city survives by importing food, energy, wood, water, building materials, and other products. The development model aims to improve quality of life. The city has been the center of political power since Aztec times, and its preeminent position forces government action. The author concludes that there are limits to urbanization, which the city is approaching rapidly.

Ufff... ¡Sin palabras!