Water Risk Adaptation in Mexico City By Regina Ynestrillas
A common challenge faced by cities over the world is water stress. As the human population continues to concentrate in urban areas ensuring that cities have access to potable water is becoming more and more challenging. Born and raised in Mexico City, a city with a complex relationship with water through history, this has become my main research focus area.
Mexico City's Metropolitan Area is one of the many megacities vulnerable to water stress. The city has struggled for decades to provide its population with safe drinking water. This vulnerability presents itself in the form of scarcity; overexploitation of resources; heterogeneity in-service conditions; dissatisfaction of users; insufficient institutional development under which it operates; and increasing social, economic and environmental costs as a result of unsustainable action, and less scope for planning and the effective solution of social demands (Tortajada, 2008). Not only are the vulnerable communities in Mexico City experiencing water shortages, but the ability of future generations to access this resource is at risk. The city faces the hydrological paradox of being a city that floods during the rainy season and faces shortages of water during the dry season.
The United Nations states that every human has the right to have access to enough quality water for personal and domestic uses. The recommended amount to meet these needs is 50 to 100 liters of water person a day (United Nations, n.d.). The average water use in Mexico City is 320 liters per person a day (SEDEMA, n.d.). It is important to note that the 320 liters is the average, so while many residents in Mexico City consume this amount or even more a day, many more don't have access to continuous tap water or quality water. The amount of water consumed a day goes as low as 10 liters per person a day (Gutierrez, 2019).
On top of the unequal distribution of water the city suffers, the available water resources for the city's consumption are overexploited. Mexico City's 8 million inhabitants, or 26 million if we consider the whole Metropolitan Area, depend on two main sources for their water; the city's aquifer and the Lerma-Cutzamala System (Gispert et al,, 2018), located more than 150 kilometers away. Today, Mexico City is one of the most hydrologically over-exploited regions globally, as total water extraction exceeds the natural availability of water in the basin by 1.73 times (Novelo & Tapia, 2012). The basin overexploitation ends up putting even more pressure on the city's underground reservoirs, which according to SEDEMA are also over-exploited.
The rapid urbanization the city has faced during the past decades and will experience in the coming years decreases the natural recharge areas of the underground reservoirs (Gispert et al,, 2018).
The depletion of the underground reservoir has led to an increasingly deteriorating situation and rapid subsidence in some areas of the city, making it more difficult for the city to provide continuous potable water to its population.
Climate change will most likely intensify Mexico City's hydrological cycle, therefore, decreasing the availability of water resulting in even more water scarcity.
High temperatures and drought, aggravated by climate change, imply increased evaporation and increased demand for water, increasing the pressure to obtain water from distant reserve areas, at exorbitant costs, or to drain underground aquifers even more and accelerate the collapse of the city, historically some areas of the city are sinking by about 30 cm per year on average but for the past ten years, the sinking rate has increased up to 1 meter per year.
Having stated the water scarcity issue Mexico City is facing is inevitable to say that developing viable innovative sustainable sources is now of the utmost importance and urgency. One of the many viable options is for the city to take advantage of rainwater. Rainwater harvesting (RWH) can be defined as a method that mainly consists of collecting rainwater from impermeable surfaces or natural land surfaces and later on storing it for future use (Rahman, 2017). RWH is a potentially sustainable source of potable water, which has proved to be efficient in different countries such as South Korea, Italy, and Basil, among others (Gispert, et al,. 2018).
Today the city is already adopting such measures; one example is the recent implementation of the "Rain Harvest Program" to improve living conditions in the communities most affected by water scarcity. For this program, the government is working together with a private Mexico City-based rainwater-harvesting social enterprise, initially created by young entrepreneurs, committed to transforming rainwater harvesting into an integral component of Mexico's water management system. This program has changed the lives of thousands of families in the city and has proved how innovative ideas and the youth can become agents and facilitators of change within our communities and cities.
About the Author
Regina Ynestrillas (@reynestrillas) is a Project Officer at the Solutions Team in SDSN Youth. She holds an MSc in Environmental Policy and Sustainability Management from The New School. She is part of the 2020 cohort Local Pathways Fellowship, where she focuses her research on the water crisis in Mexico City.
Tortajada, C. (2008). Challenges and realities of water management of megacities: the case of Mexico City Metropolitan Area. Journal of international affairs, 147-166.)
Gispert, M. Í., Hernández, M. A. A., Climent, E. L., & Flores, M. F. T. (2018). Rainwater harvesting as a drinking water option for Mexico City. Sustainability, 10(11), 3890.
Novelo, J. A. M., & Tapia, L. R. (2012). The growth of water demand in Mexico City and the over-exploitation of its aquifers. In Water resources in Mexico (pp. 395-406). Springer, Berlin, Heidelberg.