Download Mexico city water use case study - H20mx - answers

Mexico City water waste management case study – H20mx
1. Using the information above write a summary paragraph of the topography and climate of
Mexico City.
Mexico D.F is a valley of 5 lakes (biggest Texcoco). A dried lake surrounded
by mountains. Only one lake/wetland remains – Xocomilco?
Naturally ALL the rain drains into the basin with no outlet. Rainy season
(July–Oct) = high inputs of rainfall in short period, high intensity leads to
flooding.
Large areas flooded with no natural outlet/drainage such as a large river
(most capital cities have one!)
The only outlet is evaporation. Also none of this water is captured for usage
– most is lost in drains and mixed with sewerage.
2. Why does Mexico city have such a high demand for water? Where does it get most of
its water from?
High population in D.F – 22 million and set to increase = high demand for
water. Already get most of water out of state from dams (Valle de Bravo).
Much more unplanned settlements with no piped water supply.
CDMX also relies on aquifers underground but these are almost empty at the
higher levels – the soft lake bed has sunk the historic centre by over 10m.
Drilling deeper but very much into the unknown.
Most sewage is left untreated in D.F – only 8% is treated. Building 5 new
mega plants outside of city but over schedule by many years.
Management challenge
Information
Population size/demand/water
supply
Growing population and more unplanned settlement.
More demand for water.
Limited
Supply in city from aquifers and no water capture.
Water is imported from out of state
/reservoirs despite high input of rainfall.
Aquifers
CDMX also relies on aquifers underground but these are
almost empty at the higher levels – the soft lake bed has
sunk the historic centre by over 10m.
Drilling deeper but very much into the unknown.
Flooding
Naturally ALL the rain drains into the basin with no outlet.
Rainy season – high inputs of rainfall in short period, high
intensity leads to flooding.
Large areas flooded with no natural outlet/drainage such as
a large river. The only outlet is evaporation. Also none of
this water is captured for usage – most is lost in drains and mixed
with sewerage.
Sewage treatment/pipes
Water is treated but pipes are old and need replacing. Contaminates wa
Water delivered in trucks/potable –
not sustainable for many areas.
Pollution
Most sewage is left untreated in D.F – only 8% is treated.
Building 5 new mega plants outside of city but over
schedule by many years.
Heavy metal contamination – lead/cadmium/iron –
from industrial processes
3. What is ‘’the river of revenge’’ and why does it present such a problem?
River of untreated sewage – ‘’river of revenge’’ – goes out to Hidalgo state.
This is used in irrigation by farmers – better as they don’t have to buy/use
fertilizer and the crops increase yield. These foods sent back to CDMX as
revenge!
But: high levels of pollution in soils, heavy metals,
nickel/chromium/lead/cadmium
Health risks to children
4. Future management - what strategies would you use?
No overall water management strategy for CDMX area – only small scale water
capture projects.