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

Water as Leverage for Resilient Cities Asia
Semarang
Naturalization instead
of Normalization
[1]
[7]
Due to the proximity of hills and
mountains, Semarang suffers from
flash floods in the tropical season,
causing erosion, landslides and
heavy sedimentation.[1] This
natural sedimentation processes,
together with bad maintenance,
has slowly filled the rivers of
Semarang with silt.[2] Together
with the encroachment by informal
settlements, this has caused the
– now reduced – riverbeds to lose
their important role in the drainage of
surplus water during heavy rainfall.
[3]
Semarang’s government recently
initiated a program to ‘normalize’
the rivers, which implies their
canalization in order to significantly
increase their discharge speed.
[4] Most of the main canals have
already been normalized, except for
the eastern Banjir Kanal Timur. The
practice of normalization is a rather
safe solution for flooding. But the
fast and effective discharge of the
canalized rivers’ does not contribute
to the refilling of the shallow aquifers.
[5] Hence, while the process of
land subsidence keeps on going, this
creates issues in lower-lying areas
where gravitational discharge is
insufficient during high tide, so that
pumps have to be installed to clear
the surplus of rainwater.[6]
In addition to this cascading
effect, the ‘hardening’ of rivers
through canalization has negative
consequences for the ambient fauna
and flora. The embankments cut
through the natural riverbed leave
little room for potential riverine
ecosystems and habitats. Besides,
the dam used for controlling the
flash floods is situated relatively
high upstream, leading to more
salinization inland.[7] Furthermore,
the design of the canalization does
not live up to its potential as public
space; the many kilometers of hardedged
infrastructure are hardly
used for recreational purposes or
functional corridors connecting
several places within the city, nor
is it seen as a backbone for urban
development.
Could Semarang still reverse the
normalization of its rivers into a
softer approach of naturalization
and make room within the city for a
natural river system?[8] Waterways
that have enough space for a natural
river dynamic can do more than only
prevent Semarang from flooding;
by holding floodwater rather than
quickly discharging it, they can
supply water for both economic and
ecological purposes [e.g. mitigating
land subsidence] and, at the same
time, become highly accessible
landscapes and qualitative housing
environments. Naturalization
or normalization, either way, in
Semarang there is still sufficient
room to improve the relationship
between its water system and the
adjacent urban activities.[9]
[3]
[2]
[4]
[6]
[5]
SCHOOL
[9]
[8]
114 Call for Action
PART 1 / From Global Water Issues to a Call for Action
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