Collaborator: Gabriel Mendoza
SCENARIO 1 - NEZA YORK
Ciudad Nezahualcóyotl or more commonly Ciudad Neza, is a city and municipality of State of Mexico adjacent to the northeast corner of Mexico's Federal District: it is thus part of the Mexico City Metropolitan Area.
In the 20th century, the land on which Ciudad Neza sits was under Lake Texcoco and uninhabited. Successful draining of the lake in the early 20th century created new land, which the government eventually sold into private hands. However, public services such as adequate potable water, electricity and sewerage were lacking until after the area was made an independent municipality in 1963. Today Ciudad Neza is a sprawling city of over one million entirely with modern buildings. Until the 2000s, most migrants from Mexico to the United States, especially to places like New York, were from poor rural areas. However, since the turn of the century, another wave of immigrants is coming from poor urban areas such as Ciudad Neza. These immigrants tend to be younger and better educated than their rural counterparts, and tend also to keep separate from them. This is bringing into existence a new Mexican subculture called "Neza York" distinguished by dress, speech and the likelihood of learning English. Businesses with names like Tacos Neza and Neza Grocery have appeared in New York City.
SCENARIO 2 - SUBSIDENCE
As Mexico City continues to pull water from the aquifer below, its ground is sinking. The subsidence that results from groundwater extraction is a problem all over the world, but is especially dramatic in Mexico City. The aquifer has been under increasing pressure over the last several decades as the city's population has skyrocketed. Additionally, the city is mostly constructed atop layers of clay and highly permeable sand and gravel -- the type of ground most liable to collapse as water is pulled out.
While subsidence has been stabilized in the city center, many parts of the metropolitan area continue to sink. Some parts like Ciudad Neza have sunk more than 30 feet during the last century.
SCENARIO 3 – VICIOUS CIRCLE
Today the most serious damage is occurring underground, where the collapsing subsoil continues to rupture sewer lines, subway tunnels, and potable water pipes. Because the subsidence is not uniform, it has caused hundreds of millions of dollars in damage to buildings and other structures over the years, especially in the colonial-era city center.
Mexico City puts a lot of effort to stop the sinking. In some locations it has caused the sewage lines to become slanted - resulting in the lines running backward. Consequently, the city struggles with flooding during the rainy season. Emergency pumping stations have been built to maintain extraction capacity, but a major solution is still needed.
The water difficulties have become a vicious circle: as the city grows, more water is pumped from the aquifer. As more is pumped, the city sinks further. The sinkage ruptures more underground water pipes, sending fresh water gushing into the sewers, aggravating the shortage, requiring more water to be pumped from the aquifer, and so on.
HOW DO WE STOP THE SINKING OF MEXICO CITY AND ITS WATER SYSTEM CRISIS?
DESIGN CONCEPT
If Mexico City receives significant pluvial precipitation at a total rate of 215 m3/s, pluvial water is partly responsible for the urban flooding problem in rainy season, but rainwater harvesting could be part of the solution for people living in Ciudad Neza. Here, rainfall is heaviest, and the area is sufficient to collect and store water to reduce costs.
In the other hand, the total amount of wastewater treated by public wastewater treatment plants is 10 m3/s and all the treated wastewater is reused. At the present time, reused water is utilized to fill recreational lakes and canals (54%), to irrigate agricultural areas and parks over a total area of 6,500 ha (31%), cooling in industry (8%), diverse commercial activities (5%) and to recharge the aquifer (only 2%).
With all this in mind, the proposal is to replace gradually the network of small storm sewers in Ciudad Neza with a rainwater system collector that converge in recreational lakes on the surface, where towers emerge as large natural filters for rainwater storage; and treatment plants with absorption wells for underground injection. Following this system, floods will decrease because drainage system of the city will not be saturated in rainy season, and after treated water is injected directly into the aquifer, the sinking will stop.
