The head of Jakarta’s environment agency has advised that the city needs to ‘stop using groundwater’ to reduce the rapid rate of subsidence. Jakarta is currently sinking at the rate of nine centimetres per year, with some areas experiencing subsidence rates of up to 17 centimetres per year. It is expected that this rate will increase due to the growing exploitation of groundwater and greater levels of urbanisation. Increasing subsidence would exacerbate the effects of annual wet season floods, which could damage livelihoods, threaten food security and displace millions. Water containment dams, the treatment of river waters, land reclamation, a sea wall and extended water pipelines are some of the solutions that have been proposed to solve the problem. The greatest investment has been put into the contentious land reclamation project, which is currently temporarily suspended due to violations of Indonesian law.
In the past few decades, urban development reduced the green areas of Jakarta from 35 per cent to 9.3 per cent. In the city’s periphery, green areas along with water catchment areas and wetlands have also been converted to industrial estates and urban development. Land conversion has resulted in a reduction in the rate of groundwater recharge which, combined with excessive extraction rates, has rapidly lowered water tables throughout the city. If left unchecked, parts of Jakarta could soon sink below sea level.
Jakarta is the second-largest megacity in the world and is home to 10.5 million people. Groundwater withdrawal increased by 24 per cent between 2011 and 2014, and is expected to continue to rise with increasing demand. The extraction of water has left large caverns under the city that are collapsing, a phenomenon that can be seen through the cracking of buildings, infrastructure and roads. Land subsidence is also increasing inland sea water intrusion and is causing a wider expansion of inland and coastal flooding areas. This has increased the risk of contamination of the underground freshwater supply, which could have impacts on the health and water security of millions.
The government has embarked on a $40 billion land reclamation and sea wall project that aims to construct 17 new islands in an estimated 30 years. The proposed giant sea wall aims to protect low-lying Jakarta from floods. The plan, which was developed through collaboration between the Indonesian Government and Dutch firm Witteveen+Bos, has received significant criticism. The plan is expected to displace thousands of local fishers and could damage the maritime ecosystem. The project also has the potential to change sea currents and cause erosion in nearby islands, potentially increasing flooding.
Allegations of bribery and corruption have also led to regular protests against the project. Seven violations of Indonesian law have occurred during the process, leading to the project being temporarily suspended. The Jakarta City Council recently decided to stop the deliberation of two reclamation bylaws after the arrest of city councillor Mohamad Sanusi for allegedly accepting a bribe from one of the developers of the project. The Indonesian Consumer Protection Foundation has warned investors and consumers not to purchase properties that have been constructed without the developers obtaining the required permits.
Environmental experts have warned that land reclamation or the construction of a sea wall will not help stop subsidence. Only 60 per cent of people in Jakarta have access to a piped water supply; this figure has remained unchanged for many years. Without access to piped water residents will have no choice but to continue to rely on extracted groundwater. Greater focus and investment should be targeted towards treating raw water and expanding piped water coverage.
Vast potential exists for river water to assist in meeting increased water demand. Jakarta’s wastewater treatment plant has the capacity to treat less than three per cent of wastewater. Untreated household and industry wastewater are currently being dumped into Jakarta’s 13 rivers. Plans to create a higher capacity wastewater plant, however, is being delayed by disagreements between the Jakarta City Council and the government on who will provide the greater portion of investment.
The expansion of piped water coverage, treatment of wastewater and the protection of Jakarta’s rivers for future water supply should remain priority areas in order to stop subsidence.