Population ~10.7 millionArea ~661.5km22.4 Jakarta’s actions: confronting subsidence and flooding Context Jakarta, Indonesia’s sprawling megacity, is among the fastest-sinking cities globally. The city’s location on a delta plain, intersected by numerous rivers, combined with rapid urbanization, contributes to subsidence. The city has tripled in size in four decades, with the weight of development impacting its highly compressible soil in some areas. In some parts of northern districts, land subsidence has reached up to 280mm per year, primarily due to excessive groundwater extraction for domestic and industrial use.130 Accelerating subsidence increases Jakarta’s vulnerability to flooding and infrastructure damage, creating major challenges for sustainable urban planning and management. This risk is compounded by extreme weather events, including rainfall, such as the 377mm downpour recorded in a single day in January 2020, which overwhelmed and caused disruptions in some areas of the city.131Solutions Jakarta city government and national authorities’ response is defined by a multi-layered strategy that combines regulatory reforms, water resource management and infrastructure investment to reduce groundwater extraction and flooding risks. –Water infrastructure: The approach spans upstream, midstream and downstream interventions. Upstream, the focus is on expanding retention wells and reservoirs (47 built by the city, 49 by other institutions, 41 planned) to delay runoff and support downstream systems. Midstream, an extensive system of 38 primary and 36 secondary drainage channels is managed jointly by local and national jurisdiction.132 Downstream, the National Capital Integrated Coastal Development (NCICD) project features a 37.3km sea wall, polder systems and pumping stations.133 As of 2023, 8.2km of coastal embankments and retention ponds have been completed.134 The NCICD exemplifies national-level coordination, special task forces and openness to global partnerships. Resilient Economies: Strategies for Sinking Cities and Flood Risks 26

Resilient Economies Strategies for Sinking Cities and Flood Risks 2025