Tempo 2 Mar 09;
TEMPO Interactive, Jakarta:Firdaus Ali, a technical environment researcher from the University of Indonesia, predicts that Jakarta will be underwater before the year 2012. He cited as the cause the excessive suction of ground water in the Jakarta area, resulting in the continuing subsidence of the land surface. “Not only will the city go underwater, we will also suffer from dehydration prior to that,” said the doctorate from the University of Wisconsin contacted by Tempo yesterday.
Firdaus’ calculation was based on the data of land subsidence in the capital city, which ranges around 10 centimeters a year in average. In West Jakarta, during the past 11 years, the land surface subsided by 1,2 meters. In Kemayoran and Thamrin in Central Jakarta, it has lost ground by 80 centimeters for the last 8 years. “If this continues, Jakarta’s land surface will be below sea level,” Firdaus said.
City Environment Committee chief, Darrundono,
shared a similar opinion, pointing out that extreme exploitation of ground water has caused a drastic land subsidence. He said ground water supply is not increasing, yet its consumption keeps going higher. “A ground water crisis in Jakarta has come to a dangerous stage,” he cautioned.
The Jakarta administration plans to increase fees for ground water usage by luxury homes and industries to 6 – 16 times higher. This is aimed at reducing consumption which has become more exploitative.
Increasing fees, Firdaus said, is one of the instruments to reduce its usage. Users would be persuaded to use potable water from the services of the state-run Water Supply Company (PAM). “Ground water tariffs should be higher than that of PAM,” he said.
Every year, 320 million water cubic meters are sucked up from the ground, according to Firdaus. Yet, the reasonable amount should be only 38 million cubic meters. Meanwhile, the official data cites only 21 million cubic meters allowed to be consumed. “The remaining must be taken illegally,” he said.
According to Firdaus, extreme ground water exploitation creates a hollow in the earth. The resulting pressure causes the land subsidence. There are already many hollow areas around. “Even local rainfall can flood many areas,” he said.
Darrundono said the subsidence will cause Jakarta to slowly go below sea level. Sea water intrusion has currently reached 11 – 12 kilometers from the coast. “Sea water intrusion has reached the Setia Budi area in South Jakarta. Floods will become even more unmanageable,” he said. Sea water intrusion and subsidence can also cause buildings to collapse.
Darrundono criticized the construction of super-block buildings and skyscrapers in Jakarta, which also takes up excessive amount of ground water.
SOFIAN| LIS
Jakarta Sinking due to Land Structure
Tempo 3 Mar 09;
TEMPO Interactive, Jakarta: The Regional Environment Management Board (BPLHD) in Jakarta has stated that Jakarta's land level decreases every year.
“This is based on our calculations, together with academics and is similar to a statement made by University of Indonesia environment researcher Firdaus Ali,” Dian Wiwekowati, head of Environmental Impact Prevention of BPLHD, Dian Wiwekowati, told Tempo yesterday (2/3).
Last Sunday, Firdaus said Jakarta would be drowned before 2012 due to overwhelmed ground water absorption in Jakarta.
“It will not only sink but there will also be a lack of potable water,” said Firdaus, who is also a graduate from the University of Wisconsin, US.
Dian explained that Jakarta's land structure would continue sinking, however would eventually stop.
“But we do not know when it will stop,” she said.
The characteristic of land decreasing is different for every region in Jakarta.
“Certain areas like West Jakarta can decrease by as much as 1.2 meters as the land is soft,” said Dian.
She mentioned two reasons why land in Jakarta decreases.
These are pressure from buildings (87.5 percent) and ground water absorption (13.5 percent).
Data from BPLHD showed that the amount of ground water absorption was 21 million cubic meters per year.
But Firdaus Ali claimed that it is ever more at 320 million cubic meters per year while all that can be absorbed is no more than 38 million cubic meters per year.
In this case, Dian said Firdaus's calculation could be right.
“We only calculate the groundwater usage by industry sectors but not households,” she said.
There is no permission needed for ground water usage, “As it is only for basic needs,” she said.
But permission is required for commercial needs like hotels and malls.
To reduce ground water usage, the Jakarta government will increase the tariffs.
The government plans to increase groundwater tariffs for luxurious houses and industry by between six and16 times more than the original tariffs (Koran Tempo, Feb 28).
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