Challenge
Jakarta is among the most flood-vulnerable major cities on Earth. Roughly 40% of the city sits below sea level, land is subsiding at up to 25 cm per year in some areas due to groundwater extraction, and mean sea levels are rising. The combination produces chronic tidal flooding, acute river flooding during monsoons, and regular inundation of low-lying kampungs (informal settlements). Over 5 million people live in high-risk flood zones.
Multi-Layered Resilience Strategy
Jakarta’s response combines large-scale hard infrastructure with community-centred nature-based solutions and data systems.
National Capital Integrated Coastal Development (NCICD)
Phase A of the sea wall project — a 27 km outer sea wall in Jakarta Bay — has been partially completed, protecting the city’s northern coast. The project integrates reclaimed land, mangrove corridors and public amenity.
Mangrove Restoration
Working with coastal communities, the city and national government have restored over 300 ha of mangrove forest along the northern coast. Mangroves act as natural buffers, reducing wave energy, stabilising sediment and providing habitat.
Flood Early Warning System
A network of water-level sensors on Jakarta’s 12 main rivers feeds into a centralised automated alert system. Communities receive WhatsApp and SMS warnings up to 2 hours before flood peaks. The system uses historical flow data and real-time rainfall to improve forecast accuracy.
Upstream Retention Basins
Working with surrounding provinces, Jakarta invested in upstream retention basins and river normalisation to reduce peak flows before they reach the city. The EPA Stormwater Calculator was used to model the effect of different retention configurations.
Outcomes
The multi-pronged approach has reduced flood inundation area and improved early warning coverage, though Jakarta’s combination of subsidence and sea level rise means ongoing investment is essential.
- NCICD Phase A outer wall protecting the northern coast
- 300+ ha of mangrove forest restored along Teluk Jakarta
- Early warning system covering all 12 major rivers
- Flood inundation area reduced significantly following retention basin construction
Lessons Learned
- Hard infrastructure alone cannot solve a flooding problem driven by subsidence — nature-based solutions are essential complements
- Community trust in early warning systems requires sustained engagement and reliable alerts
- Upstream-downstream governance co-ordination is critical — city boundaries do not align with watershed boundaries
- Addressing groundwater extraction is necessary to slow subsidence alongside flood protection investment
Tools Used in This Case Study
Climate Tools Applied
