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

Water as Leverage for Resilient Cities Asia
Chennai
A Coast with
Two Faces
?
[6]
[5]
[7]
A relatively new threat to Chennai is
the occurrence of artificial coastal
erosion and sedimentation. Naturally,
the waves that hit Chennai’s coast
from the southeast cause a strong
longitudinal drift northwards,
resulting in a self-sustaining process
of erosion and sedimentation.[1]
The infrastructure of the harbor
docks, however, blocks these
natural flows, causing an increase of
sedimentation south of the harbor
and extreme forms of erosion on the
northern side.[2] The coast has
recently exhibited a disruption in
sediment supply and unpredictable
behavior during the northeast
monsoon. As a consequence,
the shoreline has receded by 500
meters in the last 150 years due to
coastal erosion, the coastal aquifer
has suffered damage due to the
landward shift and the coastal
highway has suffered substantial
damage, which has consequences
for traffic passing through the coastal
corridor.[3]
Infrastructural measures to reduce
erosion, such as concrete seawalls
and groins, have limited effect and
might even increase erosion on
certain locations.[4] Especially the
northern area of Ennore is eroding
fast, forcing an estimated 5500
households to move within the next
years.[5] Also a softer approach of
continuously adding sand along the
outlets of the three estuaries is not
helping. That is because the threat of
flooding is twofold: while keeping the
estuary outlet artificially narrow to
keep them under safer control, it also
increases the risk of flooding through
heavy rainfall.[6]
How can a sustainable coast
protection system be installed?
Giving the estuaries more room is
certainly a part of the solution.[7]
But also a seaward approach can be
beneficial; the careful examination of
the maritime landscape morphology
[e.g. its ridges, sandbanks, etc.]
situated in front of Chennai’s
coastline could, if put into a larger
perspective, play a key role in
an integrated coastal system of
sedimentation, erosion, salinization
and flood protection.[8]
[1]
[3]
[2]
[4]
[8]
100 Call for Action
PART 1 / From Global Water Issues to a Call for Action
101