It is ironic that many high-level
government officials, including President Susilo Bambang Yudhoyono, seemed
taken by surprise by the major floods that inundated much of Jakarta. The
President and his Cabinet held an emergency meeting to figure out how to
avoid flooding in the future.
They apparently
forgot that Jakarta is no stranger to such problems and major floods have
struck the city twice in the last 11 years. Even during the colonial era,
Jakarta experienced major floods.
Naturally,
Jakarta is vulnerable to flooding. It lies in a lowland area, with about 40
percent of its area situated under sea level. Gravity pulls water down and
settles it in the lowest area. High tides will result in the inundation of
low areas near beaches.
Furthermore, 13
rivers have estuaries in Jakarta. Heavy rain in Bogor in the south causes
an overflow of water along the river bank and finally in areas surrounding
the estuaries.
Considering the
natural setting of Jakarta from a hydrological point of view, the natural
and cheapest way to avoid floods is to let nature take its course. In other
words, leave the low lying area as the water sinks and do not build houses
in these areas.
Settlements
along riverbanks must be relocated. According to Presidential Decree No.
32/1990, riverbanks are protected areas upon which no construction can take
place.
If we let low
lying areas be wetlands, it does not mean that we are wasting natural
resources. Wetland is not wasted land.
Permanent,
relatively deep wetland, such as lakes, can be developed for fisheries and
recreation (fishing, canoeing and wild life sightseeing). Periodic and
relatively shallow wetlands can be developed as rice fields.
In the event
that we really have to build houses in flood-prone areas, the houses must
be specially designed to anticipate floods.
Several
international donors and NGOs have designed flood-adapted houses for
flood-prone areas in Bangladesh. Some traditional communities in Indonesia
living on major riverbanks have also created flood-adapted houses.
We may create
polders in low areas near the beach, like in the Netherlands, but they are
costly and not completely safe. On the nights of Jan. 31 and Feb. 1, 1953,
a combination of storms and high tides destroyed many dikes built to
prevent areas below sea level in the Netherlands. As a result, as many as 1,836
persons were killed and 70,000 more displaced.
To live in
harmony with the hydrological setting of Jakarta, we must let low lying
areas be open spaces and limit construction. What we have done, however, is
just the opposite. We have drained wetlands and turned them into
settlements and commercial areas. We have built and continue to build many
gigantic buildings, putting heavy pressure on the ground.
Furthermore, we
pump out the underground water and turn open land into concrete, preventing
the refilling of ground water. As a result, every year the ground in
Jakarta subsides, increasing the area of low land vulnerable to flooding.
To make matters
worse, development in Bogor has reduced open areas, reducing water
infiltration into the soil and increasing run off, or water flowing on the
surface.
The government
has plans to prevent the future flooding of Jakarta, such as finishing the
construction of the east and west flood canals, fortifying dikes, creating
water infiltration wells in every office, relocating residents living in
riverbanks, and perhaps most ambitious, creating deep tunnels.
The government
has also asked West Java province to rehabilitate the water catchment area
in Bogor. These plans are good and will certainly alleviate the problem.
But the most
important thing is implanting the idea that Jakarta has a limited carrying
capacity that must not be exceeded. The population of Jakarta must be
reduced, or at least, kept at the same level.
Population
growth is the root of environmental problems, including flooding. More
people need more land for housing, which results in the occupation of
riverbanks and other low laying areas.
More people
produce more waste, which may be thrown into rivers, reducing the speed and
volume of water flows. More people also need more goods, resulting in the
establishment of large shopping center buildings, putting heavy pressure on
the ground and covering a large area of land with concrete.
The government
has to create job opportunities outside Jakarta to prevent migration into
Jakarta.
We must also
stop, or at least slow down, land subsidence. One cause of land subsidence
is the decrease of ground water due to large withdrawals and limited
replenishment.
The permit for
ground water withdrawal must be limited and strictly controlled. The plan
of the government to order every building owner to construct water
infiltration wells is a good idea.
We must also
reduce the area of impervious land surfaces. Parking lots, for example, can
be made from perforated concrete, allowing water to infiltrate the ground.
Another cause of land subsidence is the construction of large buildings. We
must stop constructing extremely large buildings.
It is
impossible to defy the laws of nature. If we let Jakarta’s population grow
and we continue to construct gigantic buildings, flooding will only get
worse.
Several years
ago, some experts predicted from computer modeling that much of Jakarta’s
area would be permanently inundated in 2030.
Living
harmoniously with the natural setting of Jakarta may compromise economic
growth, but not necessarily the quality of life. If we carry on with
business as usual, we may gain economic benefit in the short term, but in
the long run we will suffer tremendous economic loss because Jakarta will
be inundated permanently and will need to be abandoned. ●
|
Tidak ada komentar:
Posting Komentar