Press Release
Wahana Lingkungan Hidup Indonesia (WALHI)
Jakarta, December 15, 2025—WALHI emphasizes that the recurring tidal surges along the northern coast of Java, particularly in Jakarta, Semarang, and Surabaya are not merely a technical issue of tidal fluctuations, but rather a direct consequence of the central government’s failed policies on spatial planning and climate crisis mitigation—policies that have long relied too heavily on concrete construction, land reclamation, and large-scale infrastructure projects as solutions.
In December 2025, tidal flooding will intensify as the 18.6-year-cycle peak of anomalous tides (highest anomaly tides) causes sea levels to rise higher, flow more rapidly, and persist longer. The issue of extreme tides is not the root cause of the problem. Coastal flooding occurs due to a combination of poor land-use planning, the loss of coastal green spaces, groundwater exploitation that triggers land subsidence, and the pressures of the climate crisis.
Wahyu Eka Styawan, Campaign Manager for Equitable Urban Development at WALHI’s National Executive Board, explained that Jakarta, Semarang, and Surabaya are the most vulnerable areas. Over the past decade, Jakarta and Semarang have been repeatedly hit by tidal flooding, even causing coastal villages to slowly sink. Surabaya also faces a similar threat, marked by coastal erosion and increasingly frequent tidal flooding in fishing villages along the Madura Strait.
WALHI’s findings over the past month indicate that the tidal flooding crisis in coastal cities is becoming increasingly serious. Jakarta was flooded again in early December 2025, when dozens of neighborhood units (RTs) in North Jakarta and the Thousand Islands were affected, as land subsidence has caused parts of the region to now lie 1–1.5 meters below sea level, thereby weakening the effectiveness of coastal defense infrastructure. An even more alarming situation is unfolding in Semarang, where extremely rapid land subsidence has pushed the Semarang–Demak coastline more than five kilometers inland since the late 1990s, making coastal flooding no longer a seasonal phenomenon but a permanent one in several areas. Surabaya also faces a similar threat, particularly in industrial and port areas, due to land subsidence and heavy reliance on groundwater, which increases the risk of tidal flooding when sea levels rise slightly above normal high tide.
The central government, through the Coordinating Ministry for Human Development and Culture (Kemenko PMK), in an effort to address tidal flooding along the northern coast of Java, has recommended accelerating the construction of infrastructure such as seawalls, integrated drainage systems, and river normalization, including supporting plans to build a giant sea wall.
“The central government’s recommendations regarding the accelerated construction of seawalls, river normalization, and giant sea wall do not address the root of the problem. The tidal flooding crisis highlights the failure of spatial planning policies that are not based on environmental carrying capacity and resilience. The Regional Spatial Planning Regulations (PERDA RTRW) of Jakarta, Semarang, and Surabaya also have not adequately addressed tidal flooding as a structural issue resulting from land subsidence and massive development,” explained Wahyu.
Therefore, WALHI urges the central government to immediately evaluate spatial planning policies, including the impact of the Job Creation Law, which promotes the centralization of spatial planning. Revisions to the Regional Spatial Planning Regulation (RTRW) must prioritize the protection and restoration of coastal areas, strict groundwater management, a halt to development that exacerbates subsidence, and the restoration of coastal ecosystems. WALHI also emphasizes the need to halt the giant sea wall project and land reclamation efforts that risk worsening coastal conditions, rather than serving as solutions to rising sea levels.
Media Contact:
Wahyu Eka Styawan
Manager of the Equitable Urban Campaign
Indonesian Forum for the Environment (WALHI)
[email protected]