Water as Leverage- Setting the scene for a call for action

Water as Leverage for Resilient Cities Asia
Chennai
From Tank to
Watershed
For its fresh water, Chennai
used to mainly depend on the
numerous lakes and tanks that
were connected by rivers and open
canals and were scattered across
the city. Due to encroachment
and pollution, pipelines linking
large, centralized water reservoirs
situated on the fringes of the city
replaced these canals. [1] As
this proved insufficient to provide
Chennai’s expanding population
with fresh water, many households
individually subtract groundwater
from the deep aquifers underneath
their houses. [2]Additionally, more
centralized and on a larger scale,
the subtraction and distribution
of deep groundwater is exploited
commercially, with trucks delivering
household water on demand
throughout the city. [3]
This infrastructural approach results
in lowering the water table all over
the city, increased polluting traffic
by the water tank trucks, and
additional manmade infrastructure
[i.e. new canals]; it is therefore not
sustainable. Moreover, Chennai’s
current drainage system has many
defects that result in frequent
flooding of streets and houses.
and numerous peri-urban water
bodies originally used for irrigation
and other [agricultural] uses. [4]
Their reactivation and linkage could
restore their close relation with the
local communities that depend on
these water bodies. In addition,
Chennai’s rather flat terrain has
enough height difference to support
draining and harvesting rainwater in
a natural and hazard-free way. [5]
To move towards a more natural
and effective watershed, a better
understanding and characterization
of each of the water bodies – and
Chennai’s topography in general – is
needed. This knowledge could serve
the city in laying out a water plan that
addresses both the water system
and the communal dependence on
its water sources. How can Chennai
create a sustainable network of wellconnected
water bodies tailored
to the city’s current scale? Which
role can each tank or tributary play
in storing, delaying, retaining or reusing
the available water? Can this
network of tanks form a watershed
that functions as a natural backbone
to manage the existing and future
urban development of this lake
metropolis? [6]
[6]
[4]
[5]
[2]
[1]
[3]
However, there is great potential
in the underused historic system
consisting of manmade tanks
(e.g. the Parthasarathy and
Marundheeswarar temple tanks)
94 Call for Action
PART 1 / From Global Water Issues to a Call for Action
95