The masterplan presents solutions for a number of problems affecting the Indonesian capital Jakarta, including flooding, soil subsidence, an inadequate water supply system and poor water quality. The document combines the proposed solutions with an analysis of the expected economic and social benefits.
Flood protection and urban development
When a public call for tenders was issued in 2012, Witteveen+Bos sought collaboration with other parties. This resulted in a consortium that also includes Grontmij, KuiperCompagnons, Deltares, Ecorys and Triple-A. Our proposal is based on a two-phase approach: flood protection in the short term, and sustainable urban development in the long term. The Dutch government (Partners for Water) decided to award the contract to the aforementioned consortium. The project beneficiary is the Indonesian government.
Every year, part of Jakarta is flooded. February 2014 was no exception: floods left some 300,000 residents homeless and resulted in dozens of casualties. The water flows into the city and simply cannot be drained off quickly enough. Soil subsidence due to groundwater extraction is a major cause of the flooding problems. In some places, the soil subsides by up to 17 cm per year. But subsidence is not the only cause for Jakarta’s water problems. No fewer than thirteen rivers flow from the volcanic hinterland into Jakarta Bay, and growing urbanisation upstream is exacerbating the problem.
Densely populated metropolis
In 2030, some 80 % of North Jakarta will be located below sea level. The masterplan calls for offshore flood protection measures in Jakarta Bay, the only area that still offers enough room for such measures in this densely populated metropolis. The coast needs to be reinforced as a temporary measure, and a new enclosure dam must be built in the bay. The dam can be financed through simultaneous large-scale land reclamation. Plans calls for a new waterfront shaped like the mythical Garuda bird, the national symbol of Indonesia. Realisation would require massive investment in one of the world’s largest hydraulic engineering projects.
The plan has been carefully assessed for its financial, technical, socio-economic and ecological feasibility. The costs of implementing the various measures are currently estimated at USD 10 to 40 billion. The accelerated construction of urban sewer systems and water treatment plants is a key aspect of the plan. This will prevent the development of a dreaded ‘black lagoon’ of sewage lapping at the city’s waterfront behind the new seawall.
Rapid construction of a complete enclosure dam between the eastern and western end of Jakarta Bay is logistically unfeasible. For instance, supplying enough soil would require more dredging vessels than are currently available in the entire world. The volume of soil needed to construct the western section is comparable to the volume required for the Tweede Maasvlakte land reclamation project near Rotterdam. Many factors will determine if and how this masterplan is to be implemented. Factors like the growth of the Indonesian economy, currently at an annual rate of + 5 to 6 %, or presidential elections. To tackle the problems in phases, a sound plan has been prepared.