The Urban Water Cycle Mexico City as an

The Urban Water Cycle: Mexico City as an example Blanca Jiménez

Mexico City • Tenochtitlan was founded by the Aztecs in 1325 d. C • In a SAFE Place and plenty with water • BUT that meant that the Mexico Valley was an endorreic basin at 2, 240 masl

Water Cycle in the Mexico City Valley

The Spanish arrived, in 1519 d. C. ü Tenochtitlan was a “Megacity” – 200, 000 inhab. –Four streets (dikes) communicated it with land separated 5 lakes ü The Spanish people –Did not understand the functioning and destroyed dikes –Rivers were used as sewers Tenochtitlan was the most important city and was an island ü Since then both lack of water and floods are the main urban water problems

Mexico City in 2010 ü 21, 000 million people ü Metropolitan area = the Federal District (Tenochtitlan) + 37 adjoining municipalities ü Water is managed independently in the 38 entities ü In total, 85. 7 m 3/s (7. 4 MILLIONS m 3/d) Ø 48% through the network Ø 44% directly pumped by the water works utilities, farmers and industries from the local water Ø 8%, reused treated wastewater

WATER SUPPLY AND USE First use water (78 m 3/s) comes from : Ø 73% from 1, 965 wells located within the City Ø 1% from local rivers Ø 7% from the Lerma (100 km far and 300 m above the Mexico City level ) Ø 19% from the Cutzamala river (130 km away and 1, 100 m) 3. 4 times the Eiffel Tour Height

Water Uses ü 74% municipal and industries branched to the city network ü 16% irrigation (40, 000 ha on the Valley) ü 2% self supplied industries ü 8% non drinking water reuse

Water supply service ü 89% coverage , i. e. , 2. 3 million people receive water through water tanks üThey pay 10 times the network water price üThe rest, receive water through the network üBUT they receive it intermittently üPoor quality üAs consequence each house has their “own storage (TINACOS) and pumping systems and potabilize water

Water sources quality Parameter , mg/L Original Present value Dissolved Solids 1, 000 20, 000 Sodium 50 -100 600 -800 Ammonical 0 -0. 03 6 -7 nitrogen Iron < 0. 1 3 -7 üLocal groundwater quality is increasingly deteriorating üDue to overexploitation, uncontrolled non source point pollution, and industrial and municipal discharges -

Water quality and drinking water sources In groundwater: In the western part (uncontrolled dumping sites used to exist) § High content of a wide variety of organic compounds (even vitamin B) - In the southwest § High Fe and Mn content - In the South (no sewer and 500, 000 septic tanks discharging sewage to a volcanic soil § Nitrates, ammoniacal nitrogen and fecal coliforms

To potabilize water ü Chlorination for groundwater sources and Alum coagulation, sedimentation and chlorination for surface water ü Processes selected based on characteristics measured 30 -40 years ago, i. e. , pollutants of concern are not remove ü In chlorinated water § THM (Trihalomethanes, carcinogenic) § 84 microorganisms of 9 genera associated with human fecal pollution (Streptococcus, Helicobacter pylori -associated gastric ulcers and cancer and coliphages MS-2, before and even in some cases after chlorination - resistance to chlorine? )

To have potable water ü Each user § Boils, apply chemical disinfectants (chlorine, iodine or silver), uses small potabilization systems (filtration with ozone or UV-light disinfection) § Potabilization cost varies between 4 -10 USD/m 3} ü Or buys bottled water § Mexico is the 2 nd consumer of bottled water § Bottled water is 240 to 10, 000 more expensive than tap water ü Cost represents for a family of 4 persons living on minimum wage 1121% of its income

IMPACTS DUE TO THE EXCESIVE WATER DEMAND 1. Overexploitation ü of the local aquifer at a 117% rate ü As a result there is soil subsidence ü sinking rates in some places up to 40 cm/year ü In 1954 the problem was perceived but center had already sunk 7 m 1910 1980

2. Soil subsidence is creating ü Loss of the sewage/drainage capacity (no slope or inverted slope) ü 20 -30 floods per year > 30 cm in height with wastewater ü To recover capacity 305 million USD are being invested

ü Difficulties to maintain the Deep Drainage as it conveys all year round wastewater ü If it fails, 400 km 2 of the City center will be flooded with 1. 2 m of wastewater affecting at least 4 million people.

2. Soil subsidence is creating: ü Structural problems in buildings ü For Mexico City Cathedral § Differential soil sinking has led to an 87 cm difference between the apse and the western bell tower in 50 years § To redress it $ 32. 5 million USD were invested in 2000 ü The metro (metropolitan train) rails need to be leveled each year

2. Soil subsidence is creating ü Leaks in water and wastewater networks. § 40% of the water supplied is lost, amount enough to supply 3, 200, 000 million people with 300 L/capita (the actual supply is 153 L/d ) ü Sewage leaks § Have not been evaluated

3. Due to the Water transfer from other basins At the Lerma region § which used to be a lake, fishing disappeared and people had to live off the land. § The Chapala Lake fed by the Lerma system has experienced a level decrease of 5 m. ü Cutzamala region § Reduction of the amount of water available for power generation and local population § Women mazahuas

ATMOSPHERIC DEPOSITION • In 1998 the regular presence of gasoline and oil-derived compounds in Mexico City’s wastewater was reported. It may come from Ø Air pollution (3 million automobiles that “discharge” (evaporation) 82, 000 tons/yr Ø Oil pipelines leaks Ø solvents used as cleaning products (77, 000 tons/yr) Øevaporation and leaks of unburned oil (27, 000 tons/yr) domestic gas leaks Ø dry cleaning services Øchemical industry Øgraphical arts.

Air pollution • The average concentration of HC in Mexico City’s air is 8. 8 ppm (2 ppm in Los Angeles in the 1980 s), among the compounds reported there are – Toluene, benzene and formaldehydes – formic acid (2 -24 μg/m 3) – acetic acid (0. 5 -7 µg/m 3) – propionic acid (0 -18 μg/m 3) – close to 200 volatile organic compounds with at least 2 -13 carbons have been identified – alkenes (52 -60%) – aromatic compounds (14 -19%) – olefins (9 -11%) – oxygenated compounds (1 -2%) – MTBE Automobiles also produce • 19, 889 tons of < 10 micron particles, • 22, 466 tons of SO 2 • 1, 768, 836 tons of CO • 205, 885 tons of NOx • 465, 021 tons of hydrocarbons

SOLID WASTES FROM SEWERS • Mexico City sewer system is VERY BIG and COMPLEX ü The Sewer system is cleaned each year ü 2. 8 million cubic meters of sludge/solids wastes are produced

üWastes go to the ONLY municipal landfill that is already overloaded üSediments contain ü 3 -7 log faecal coliforms MPN/g TS ü 2 -7 log Salmonella MPN/g TS ü 4 -21 viable helminth ova /g TS ü 89 -7955 total petroleum hydrocarbons (mg/kg TS) üheavy metal üorganic matter, nitrogen and phosphorus üSimilar problems in Sao Paulo and Taiwan have been reported

Sewerage system, History ü 3 artificial exits built to drain waste and pluvial water ü In total, Mexico City produces 67. 7 m 3/s of wastewater ü 11% is treated and reused since 1956 ü The rest, (60 m 3/s, mean conditions but varying from 52 to > 300 m 3/s) IS non TREATED AND ALSO RESUED since 1896 for irrigation of the Tula Valley ü 100% OF WASTEWATER REUSE

Reuse is for • 54% refill recreational lakes, • 31% green areas irrigation (6, 500 ha), • 5% car washing and fountains • Environmental restoration, • 8% industrial uses (Cooling)

The Tula Valley, Description ü Semiarid area § Pluvial precipitation: 525 mm (5 months per year) § evaporation rate: 1, 750 mm ü Original vegetation: Xerophila scrubs, such as mezquite, sweet acacia, yucca and a wide variety of cacti ü 1930 -40 s the Government was thinking on moving people, there was NO water for development

The biggest WW irrigated district in the world ü From s 14, 000 ha inn 1926 it reached of 90, 000 ha in four irrigation districts ü Among the most productive ones¡¡¡ Crop Yield, tons/ha Increase Wastewater ‘First use’ % water Corn 5. 0 2. 0 150 Barley 4. 0 2. 0 100 Tomato 35. 0 18. 0 94 Forage 22. 0 12. 0 83 oats Alfalfa 120. 0 71 Chili 12. 0 70 Wheat 3. 0 1. 8 67

Health effects Parasites Ascaris lumbricoides (Helminth) Giardia lamblia (Protozoa) Entamoeba histolytica (Protozoa) Ages 0 to 4 5 to 14 > 15 0 to 4 5 to 14 < 15 Morbidity rates Raw Natural wastewater 15. 3 2. 7 16. 1 1. 0 5. 3 0. 5 13. 6 13. 5 9. 6 9. 2 2. 3 2. 5 7. 0 7. 3 16. 4 12. 0 16. 0 13. 8 Ratio 5. 7 16. 0 11. 0 1. 3 1. 2 Cifuentes et al. , 1992 Data used by WHO (1989 and 2006) to establish the criteria to reuse wastewater for agricultural irrigation To be controlled with a WWTP (under construction)

Secondary effect ü Discovered in 1995 § At least 25 m 3/s of wastewater used to irrigate were infiltrated to the local aquifer (13 times the natural recharge) ü Due to § wastewater transportation in hundreds of unlined channels, § storage in unlined dams, § high irrigation rates (1. 5 -2. 2 m/ha. yr) to wash out salts ü As a result § the Tula River flow (partially fed from the aquifer) increased from 1. 6 m 3/s to more than 12. 7 m 3/s between 1945 and 1995 § the water table rose from 50 m below the ground level in 1940 to form artesian wells with flows varying from 40 to 600 L/s in 1964 ü The new water sources § Are used to supply 500, 000 inhabitants after only chlorination

Tula Valley without wastewater for irrigation

Tula with a “wastewater river” for irrigation

Groundwater and drinking water quality ü In 1938, a change in the water quality of wells began to be noticed ü In 1995 it was officially acknowledged that § infiltrated wastewater was the origin of the new water sources § It was the as supply for 500, 000 inhab ü Several studies to assess the water quality begun

Results Ø No main problems Ø Water was light saline Ø In wells built with no care some microbiological problem Why not using it for Mexico City supply?

Future water demand Actual deficit Continuous supply + 5 next years demand Over exploitation and soil subsidence control A>t least for 2010 1 -2 m 3/s 5 m 3/s >15 m 3/s 25 ü Option to supply this demand § Transferring water from other basins and/or § Aggressive water reuse programs § On site wastewater potabilization OR § Returning back groundwater from the Mezquital Valley

Cost comparison of different new water source options for Mexico City (Jiménez and Chavez, 2004) SOURCE Temascaltepec Amacuzac Tecolutla Mezquital Valley Mexico City (Reuse) Capacity m 3/s Head m Distance km 5. 0 13. 5 9. 8 10 >10 1570 1700 1266 400 0 80 100 116 70 0 Cost (US$/m 3) 0. 58 0. 86 0. 85 0. 25 1. 5

Excessive water demand in a Transportation of polluted water Atmospheric deposition limited area in open channels or rivers • Air pollutants by direct -Water efficient Use - Specially in poor periruban deposition or settling are - Water Reuse Dumping sites, municipal landfills and Non intentional Reuse of treated transfer areas water. sites - Urban Growiing balnace with the hazardous wasteto and non treated wastewater confinement Infiltrate or discharge CONTROL and solid Especially POLLUTION into water wastes local water availability products AIR old landfills (<1970’s) Industrial non point sources –Infiltration wells as wastewater disposal option water Emerging pollutants sources Reintegrating used discharges BETTER SURVEILLANCE OF SURVEILLANCE, TRACKING AND THE WASTES rather than disposal MANAGEMENT IN • concept of liquid courses Handling Treated wastewater SOCIAL Urban Septic tanks INDUSTRIES; CLEANER> PRODUC TION CONCEP AND disposal CONTROL concept DICHARGING AND ENVIRONMENTAL RESPONSIBILITY APPRAOCH 70% of the During the dry season § Discharge partially treated TRANSPORTING DO NOT GET water supply in the Tamesis river wastewater Leaks in the water network RID OF POLLUTION (England) comes from Sewers: Infiltration gasoline, oil § In Sana’a, Yemen WWTP From 8 -60% Subsurface storage tanks ( effluents Storage highly Tanks/Ponds of the urban As or chemical compounds)OF high as 500 mm/yr in or treatmentrepresent 80%(containing MAINTENANCE leak wastewater, old populated urban > 20 IN WHICH URBANINFRASTRUCTURE THE WAYrecharge or Especially if they areasyears industrial liquid wastes , WTP ARE stormwater) frequently leak CHANGE SEWERS MAINTENANCE CONCEIVE NEED TO MONITORING AND MAINTENANCE NEW SOLUTIONS FOR ON TO • Even if infiltration occurs (10 -20 PROGRAM waterproofed, CLOSE TREATMENT LOOP SITE THE WATER mm/d) MONITOR AND CONTROL OF NON POINT URBAN DISCHARGES TO SOIL AND GROUNDWATER

CONCLUSIONS • Mexico City is one example, but there are many other (similar or parts, developedn and developing) • Cities need water (in appropriate quantity and quality) • They modify the water cycle in many ways • Impacts often are overlooked putting at risk cities and the “urban water” sustainability • To control such impacts – causes need first to be acknowledge and identified – appropriate and affordable measures should be put in place • For both the hydrological urban water cycle concept is useful and to study it inter/transdiciplinary effort need to be made

Water Network IANAS Dr. José Galizia Tundisi Dra Blanca E Jiménez Cisneros

IANAS Water Programme • (a) establish National Water Committees that will help Academies provide advice to governments and society, thus enhancing their social relevance; • (b) prepare white papers providing a strategic view on national water resources; • (c) implement capacity building activities; • (d) discuss new perspectives and innovative solutions for water management; • (e) set the stage for the future publicizing and implementation of the recommendations of the IAC Study Panel on Water.

Meeting in Domingo, 29 February to 01 March 2008 1) 2) 3) 4) 5) 6) Argentina, Raul Lopardo Bolivia, Fernando Urquidi Venezuela, Ernesto Gonzalez Brazil, Jose Galizia Tundisi Canada, Keith Hipel Cuba, Mercedes Arellano 1) 2) 3) 4) 5) 6) 7) Guatemala, Manuel Basterrechea Haiti, Wilson Celestin Nicaragua, Katherine Vammen Peru Adolfo Toledo and Axel Dourojeani Dominican R. , Rafael Osiris de Leon Trinidad & Tobago, Vincent Cooper United States, Henry Vaux

Water in X COUNTRY , Book • Water Resources • Water and sustainable development • Climate Change and Water • Groundwater/Ecohidrology • Water Quality • Water and ecosystems • Limnology • Water and Health • Water Services for Municipalities • Water, Livestock and Agriculture • Water and industry • Urban Water • Water and Ecotourism • Water and Energy • Water and Transportation • Aquaculture • Hydroeconomy • Institutional and Legal Framework • Water and Women • Public Participation NEXT STEP

IN SEVERAL CASES THERE ARE > 1 author COUNTRY Argentina Bolivia, Fernando Urquidi Brazil Canada, Keith HIpel Chile, Niño Yarko Colombia, Gabriel Roldán and Claudia Campuzano Costa Rica, Hugo Hidalgo Cuba, Mercedes Arellano Acosta Guatemala, Manuel Basterrechea Haiti, Wiston Celestin Mexico, Blanca Jimenez Nicaragua, Katherine Vammen Peru, Julio Kuroiwa Dominican R. , Rafael Osiris de Leon Trinidad & Tobago, Vicente Cooper United States, Henry Vaux Venezuela, Ernesto González TOR Presentation OK OK OK English Version In process OK OK OK OJ OK OK OK In process OK OK In Process In process OK OK OK In process Spanish Version In process OK OK White Paper In process OK OK OK In process OK OK Book

NEXT STEP, 5 th Meeting in Argentina • End country profiles • End white paper • Begin of URBAN water – 60% of World population live in cities – But, in LA is 70% ¡¡¡¡¡¡ Think Water¡¡¡