Floods
and raising the city
Tri Harso Karyono ; Professor of
architecture at Tanri Abeng University (TAU),
Author of Green Architecture (2nd edition, 2014)
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JAKARTA
POST, 05 April 2014
Recent
news reports stated that the Dutch were ready to help find a solution to
Jakarta’s severe annual flooding.
Coastal
development is being considered to prevent the capital from being inundated
by seawater. Due to global warming, millions of people worldwide who live in
coastal cities like Jakarta will face increasingly serious floods as sea
levels rise due to melting polar ice.
Global
warming, in which the average earth temperature rises, is caused by excessive
greenhouse gas (GHG) emissions. Buildings account for around 15 percent,
while transportation and industry contributed 14 percent and 21 percent,
respectively, and the remainder was emitted by other activities.
The 1997
Kyoto Protocol suggested that a number of industrial countries should reduce
their carbon emissions by 5 percent from 1990 levels by 2008 through 2012.
Levels were evaluated in 2012 to determine the impact of the Kyoto Protocol
on reducing global carbon emissions. The evaluation found that some developed
countries, like the UK, France and Germany and most of those in Eastern
Europe, had successfully reduced their emissions — and by more than the
targeted figure; while other industrialized countries, like Canada, Australia
and Japan, had failed to reach the mandated goals.
Despite
the efforts, global carbon emissions are continuing to increase, reaching 34
billion tons recently, and threatening a rise in global temperatures of up to
7 degrees Celsius by 2100. In her 2009 book, Adapting Buildings and Cities
for Climate Change, Sue Roaf of Heriot-Watt University in Edinburgh,
Scotland, stated that sea levels had risen at a rate of 0.1-0.2 millimeters
per year over the past 3,000 years, but that in the 20th century alone, this
had increased to 1-2 mm per year, or about 10 times faster than previously,
due to global warming.
This
phenomenon creates heavy flooding, particularly in coastal areas, which means
that cities like Jakarta would become flooded even in the absence of rain, as
rising seawater encroached onto the land.
Jakarta
has seen massive development with the construction of an increasing number of
buildings and roads, creating more land surfaces covered with hard materials.
Since the city has no integrated drainage system to accommodate rainwater
runoff, it is becoming ever more vulnerable to flooding and increasing the
urgency to find a solution.
Our
forefathers managed their immediate environment wisely. In a number of
vernacular societies, people built houses on stilts to protect themselves
from would-be invaders, as well as wild animals such as tigers. Stilt houses
also provide good protection against flooding as the ground surface beneath
the house is open and uncovered, allowing it to absorb rainwater and other
inundations.
If we
want to create a sustainable city, namely a city that experiences
less-frequent flooding or even no floods at all, we should emulate our
forefathers. The book, Time To Eat The Dog: The Real Guide To Sustainable
Living (2009), states that the human race could survive on the planet’s
natural resources if we all lived in the same way, namely in a way akin to
our great-great-grandparents over 100 years ago.
A city
could be built on stilts, in which its multistory buildings and roads would
be elevated, leaving the ground surface open. The open ground surface beneath
a building’s ground floor would be laid with water-absorbing materials like
concrete blocks, to enable the speedy absorption of rainwater. The space
would not be allocated for any permanent structures, other than vertical
structures such as stairs, escalators and elevators. No basements would be
allowed; any that were already built would be used as water tanks to
accommodate runoff.
The
opened ground floor of the building would not only enable the absorption of
excessive rainwater, it would also provide space to accommodate excessive
rainwater in case of flooding. If this idea was applied to 60 percent of
existing high-rises and 100 percent of new buildings, the area of uncovered
ground surface in Jakarta would significantly increase, which would
substantially reduce the amount of runoff.
By
having many multistory buildings with open ground floors, air movement around
the city would be accelerated, creating a cooling effect amid Jakarta’s
tropical climate. Furthermore, in the very near future, we should stop
enclosing the land around buildings. Outdoor spaces surrounding buildings in
the city should be considered public space that can be used by everyone. This
would help to create shortcut access routes, encouraging more people to move
around the city on foot and by cycling around and beneath these buildings.
Main
roads, which would cater to motorized vehicles, would be elevated, while
beneath them, there would be smaller arterial roads, pathways and gardens for
cyclists and pedestrians. Divisions would be made between non-motorized and
motorized vehicles when entering the building. Pedestrians and cyclists would
enter the building from the ground floor, while people on motorized vehicles,
mainly public transportation like the monorail, would enter the building at
the lobbies on the second or third floors, which would be at the same level
as the elevated roads.
The
question is how can we put these ideas into practice? How can we remove the
ground floors of many existing buildings in Jakarta in order to make them
rainwater absorbent? How can we transform basements from what are mainly car
parking areas into rainwater tanks to prevent flooding?
The
Jakarta administration could issue a decree to oblige building owners in
flood-prone areas to transform their buildings. This process could be carried
out in stages to avoid the disruption of activities inside the buildings.
The
local authority could also construct the elevated roads and flyovers in a
gradual process. If all these measures were implemented, they would go a long
way toward facing global warming and mitigating its threats, and they would
also help Jakarta reduce its annual flood risk. ●
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