Rehabilitating waterways in Indonesia’s capital to mitigate flood risks

17 Januari 2012

  • Floods in Jakarta are expected to become more frequent in coming years causing severe socio-economic damage
  • One major cause of floods is the reduction of waterways’ capacity flow due to sediment build up and lack of solid waste management
  • The World Bank will support the Jakarta Government by rehabilitating some of the waterways to mitigate flood risks

Jakarta, January 17, 2011 -Throughout this January 2012 thus far, very rarely has there been a bright sunny day in Jakarta. Rain has become more frequent and intense accompanied by strong winds, increasing flood risks to the city. Jakarta suffers from perennial flooding, with the last major events occurring in 1996, 2002 and 2007. The February 2007 event inundated 235 km2 or about 36 percent of the city by up to seven meters in some areas. That year, 70 people were killed and 340,000 thousand had to flee their homes. Some people talk about the so-called five-year cycle of big floods, anticipating another one in 2012.

Since 2007, floods continue to occur in Jakarta under any sustained rainfall conditions. In 2008, floods closed the airport toll road, cancelling over 1,000 flights and caused serious disruptions for the city. Flood incidences in 2009 also occurred at high intensity and have continued into 2010, which became the year without a dry season due to the La Niña effect.

A city prone to floods
Floods in Jakarta have been recorded as early as the 17th century, long before the city was called Jakarta. The city is surrounded by dormant volcanoes whose slopes form the upstream catchment areas of 13 major rivers that flow through Jakarta leading to the Java Sea. Jakarta sits in the lowest lying areas of the basin. Today, forty percent of the city lies below sea level, and acute and ongoing land subsidence threaten to make matters worse.

With around 250,000 new residents coming to live from other parts of the country annually, rapid expansion of the city has added to the cause of floods. City infrastructure, buildings and houses built along river banks and critical catchment areas have severely reduced the flow capacity of waterways. Increased sediment loads and inadequate management of solid waste have contributed to waste choked canals and floodways, with some operating at less than a third of their original capacity.

Rehabilitating waterways to mitigate floods
To reduce flood risks in the city, the Government has made significant investments and efforts in recent years  to protect Jakarta against floods, such as constructing sea walls and the east flood canal. However, huge challenges remain on this complex issue. As the next step, the Government with the support from the World Bank will implement a project to rehabilitate some of the city’s waterways. Under the Jakarta Urgent Flood Mitigation Project, also known as Jakarta Emergency Dredging Initiative, selected priority sections of floodways, canals and retention basins will be dredged allowing the flow capacity to return to their original state. Garbage pile-up which has also clogged the city’s waterways will be disposed using proper facilities at separate locations.

Flood mitigation cannot be limited to physical work alone. “Flood management in Jakarta is complex requiring efforts to resolve difficult issues on many fronts, each of which may be under the institutional responsibility of different stakeholders,” said Fook Chuan Eng, Senior Water and Sanitation Specialist at the World Bank’s Office in Jakarta. To address this, the five-year project will also look into the capacity and coordination between national and local agencies responsible for the city’s flood management.