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At least a quarter of Jakarta would be underwater by 2050 if current rates of development projects and groundwater harvesting continued unabated, a climate expert warned on Wednesday.

Armi Susandi, a climatologist from the Bandung Institute of Technology (ITB), said the northern part of Jakarta would most likely be permanently submerged by 2015.

“I am talking about Cilincing, Muara Baru and Tanjung Priok”, he told the Jakarta Globe on Wednesday.

“Meanwhile the Soekarno-Hatta International Airport [located in Tangerang, Banten] will be underwater by 2030.”

In a 2009 ITB study on land subsidence and urban development in Jakarta, Indonesian and Japanese researchers showed that an increase in population and urban development activities in the capital was driving the subsidence because of the sharp increase in built-up areas and decrease in natural green spaces.

The problem has been exacerbated by factories, hotels and wealthy residents drilling their own deep-water bores to bypass the city’s water grid, sucking out the groundwater and causing further subsidence. Jakarta’s limited pipe network for clean water means that about 40 percent of residents have to pump their own groundwater.

The soft ground that makes up most parts of Jakarta, the weight of ever-expanding road infrastructure and buildings and the excessive exploitation of groundwater all play a part in the city’s subsidence.

In 2005, Armi, together with ITB oceanographer Safwan Hadi, created a simulation that suggested that by 2050 a quarter of Jakarta would be submerged by the sea.

“Sudirman and Kuningan areas will still be there by 2030,” he said, in an apparent reference to media reports on Wednesday that half of the city, including Sudirman in Central Jakarta and Kuningan in South Jakarta, would be inundated by seawater by 2030.

Armi explained that his simulation had used a spatial and periodical projection of the depreciation of the ground level in Jakarta versus the rising sea level. The simulation utilized what he called a “digital evaluation model,” which he applied to the Greater Jakarta area to project the impact if nothing was done between 2005 to 2050, using 5-year intervals.

According to his simulation, Merdeka Square and its surrounding areas in Central Jakarta would be under water by 2080. “So Sudirman and Kuningan should also be underwater in about that year,” Armi said.

The parameters used for his simulation were an average rise in sea levels of 0.57 centimeters per year, and a ground level subsidence rate of 0.8 centimeters per year. “So the average sinking rate will be 1.37 centimeters a year,” he continued.

However, the World Bank in 2008 said that Jakarta was sinking by as much as 4 to 10 centimeters annually.

Armi argued that the projection he made was according to actual sea and coastline conditions, and with the use of global positioning to measure the rate of sinking in Jakarta.

Despite his less-catastrophic prediction, Armi still called on the government to solve the problem. “Jakarta has to adapt permanently by building sea walls along the coastlines of North Jakarta. The walls should be built by 2015,” he said.

The wave breakers currently being built in North Jakarta, he said, would only help to prevent tidal surges during extreme weather conditions.

“What we need are sea walls,” he said, adding that the walls should be at least two to three meters above sea level and six meters thick to be able to protect the city from the ocean, which he predicted could rise by one meter by 2100. Ulma Haryanto