Jakarta, Indonesia, with a population already over 10 million, is one of the fastest-growing cities in the world. It’s also one of the fastest-sinking cities. Every year, the ground subsides by as much as six inches in some neighborhoods. At that rate, as sea levels rise, northern Jakarta could be a few meters underwater by 2030.

In response, the city is embarking on one of the world’s biggest infrastructure projects. Over the next three or four decades, the government plans to build a 21-mile long sea wall and 17 artificial islands to help protect the city from flooding. It will cost around $40 billion.

The project, like other new infrastructure for the quickly growing city, will be a challenge to pull off.

“Limited funding and a complex urban setting are two main challenges,” says Victor Coenen, project manager for Witteveen+Bos, a Dutch firm that helped Jakarta create a master plan for the project. “The government is struggling to keep up with the pace of growth. Also, planning and construction of infrastructure is complicated in the densely populated metropolitan areas–relocation of residents is controversial, complex, and costly.”





Even the technical details of the plan are an enormous challenge. Just supplying as much soil as the project needs will take more dredging vessels than are currently available in the entire world. Still, the master plan found that the project was feasible, and this month, the city took the first steps in construction.

The project is starting by temporarily bolstering Jakarta’s existing sea wall. As parts of the city sink–a process driven by the fact that the city has been pumping out more and more groundwater for the growing population–and tides rise, the current wall isn’t high enough.

In 2007, seawater crashed over the sea wall in northern Jakarta for the first time, adding to flooding from heavy rains that forced 500,000 from their homes. A year ago, the sea level came just inches from breaching the sea wall again, putting millions of people at risk.