Presentation by Stefania Valenzuela Velazquez (Deltares) at the iMOD International User Day, during Delft Software Days - Edition 2017. Tuesday, 31 October 2017, Delft.

1. Groundwater assessment of the
Basin of Mexico
A Resilient Water System for Xochimilco

2. Case study

3. • Mexico is facing enormous water challenges such as water pollution, water
scarcity, poor water management and lack of long-term strategic water goals
(Arreguín Cortés et al.,2011)
• It is estimated that 70% of the drinking water provision in Mexico City is carried
out throughout groundwater (Tortajada & Castelán, 2003).
• The RWSX project aims to restore the water system of Xochimilco in a way that it
can cope with climate change and the socioeconomic challenges that are
pressuring the water system.
Introduction

4. Basin of Mexico - Boundary conditions
Population (2015) 21,629,399
Water demand: 230 l/p/d
5,108,512 m3 per day
70% of the water demand is
extracted from groundwater sources
Surface: 9,739 km2
Elevation: 2240 m a.s.l.
Population Mex (2013) : 122 300 000
• Supplies water to 16 boroughs of Mexico City, 50 municipalities of the State of Mexico, 15
municipalities of Hidalgo and 4 municipalities of Tlaxcala
• Closed basin of lacustrine character

5. • Analysis from 1995 to 2015.
• Two seasons dry (November -May) and rainy (June-October)
• Conceptual Model
• Water balance based on the following expression:
𝑅 𝑐𝑎 + 𝑅 𝑎𝑟 + 𝑅 𝑟𝑟𝑔 + 𝑅𝑙𝑜𝑠𝑠 − 𝐷𝑐𝑝 + 𝐷 𝑛𝑓 = 0
RCa is the recharge through water flow in rivers
Rar is the diffuse recharge from rainfall
Rrrg is the recharge from irrigation
Rloss is the groundwater recharge due to water losses in the pipelines
Dcp is the water abstraction from wells
Dnf is the natural groundwater flow
• Numerical Model
• Steady State
• Transient State with annual and seasonal patterns
Methodology

6. Hydrogeology
4 units distinguished in the basin: 1
Upper aquitard: formed by lacustrine deposits from the Quaternary.
(60 m)
Upper aquifer: It is composed of alluvium, pyroclastics, conglomerates,
igneous rocks and other volcanic sediments from the Quaternary.
(600 m)
Lower aquitard: formed by lacustrine deposits from the Pliocene and
volcanic rocks from the Oligocene-Miocene. (1500 m)
Lower aquifer: constituted by carbonate rocks from the Lower
Cretaceous. (500m)
1Herrera, I., Martínez, R., & Hernández, G. (1989). Contribución a la Administración Científica del Agua
Subterránea de la Cuenca de México. Geofísica Internacional.
Geological-Hydrological isometric from the Valley of Mexico
(Retrieved from Lesser y Asociados S.A. de C.V., 2000).

7. Groundwater abstractions from 2871 wells:
Groundwater abstractions

8. Average Rainfall
• The Basin of Mexico has 117 meteorological stations, the model considers only 73
stations.
• Average rainfall of 1,000 mm per year (May-October)
(Gomez Reyes, 2013).

9. Average Recharge (mm/season)
Average recharge
Rainy season 1995
Average recharge
Rainy season 2010

10. Lesser-Illades, J. M. (2005). Evolucion Piezometrica del Acuifero de la
Ciudad de Mexico. V Congreso De Aguas Subterráneas, 1–9.
Preliminary Results
Groundwater heads:
• Groundwater levels seems higher than levels reported by CONAGUA and Lesser-
Illades (2005)
Simulation for 1995 (mean annual precipitation and annual
water extraction)
Hydraulic heads (1995)

11. Groundwater heads:
• Water levels seems erratic thought the period of analysis (1995 – 2015)
Preliminary Results
b)
a)
c)
e)
d)

12. Groundwater heads:
Preliminary Results
Time series in the area of Xochimilco
c)
Time series in the area of The State of Mexico
a)

13. Conclusions
• Inconclusive results were obtained due
to the high uncertainty in the inputs of
the numerical model.
Next step:
• New time frame 1979-2015.
• Water extractions are going to be
updated with real extraction rates.
• The hydrological model will be done
with WFlow.

14. Questions?
Gracias por su atención!
Thanks for your attention!

15. Remarks!
• There is Spanish version of
the user manual.
http://oss.deltares.nl/web/im
od/user-manual