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Sinking

The capital of Indonesia is being governed into the ground; in parts of North Jakarta, land subsidence has reached rates of up to 20 cm per year and, in some areas, several metres over recent decades.

As a result, many neighbourhoods now lie below sea level, leading to chronic tidal flooding and seawater intrusion into homes and infrastructure.

Along Java’s northern coast, similar patterns are unfolding in cities such as Semarang and Pekalongan, where tidal flooding – locally known as rob – has become routine. In low-lying districts, roads disappear under water for hours or even days, factories operate behind improvised sea defences, and fishing communities contend with the steady erosion of both land and livelihood.

What were once seasonal floods have, in many places, become semi-permanent conditions.

Across this coastline, the crisis is driven as much by policy failure as environmental change. Rising sea levels matter, but land subsidence – caused primarily by excessive groundwater extraction and weak urban water governance – is accelerating the process. In effect, parts of northern Java are sinking faster than the sea is rising, turning coastal flooding from a future threat into a present infrastructure condition.

An often-overlooked dimension is that this is a governance problem embedded in water provision. In Jakarta, incomplete piped-water coverage continues to push households and industries toward groundwater extraction despite formal restrictions. Weak enforcement and fragmented authority between municipal and provincial agencies mean that regulation exists on paper but is inconsistently implemented in practice.

The result is a self-reinforcing cycle: insufficient public water supply drives groundwater use, which accelerates subsidence, which in turn intensifies flooding and infrastructure stress.

Strategic Workaround?

Against this backdrop, the plan to construct a giant sea wall along Java’s northern coast is being framed as an urgent response. Under President Prabowo Subianto, the project is evolving into something more than a coastal defence: a flagship initiative linking climate adaptation, economic nationalism and strategic statecraft.

Recently, the government has even established the North Java Coastal Management Authority to oversee this massive endeavour.

However, this mega-project is not simply a response to environmental risk. It is better understood as a governance workaround made visible in concrete—an attempt to manage accelerating coastal collapse without resolving the institutional conditions producing it.

In this sense, the sea wall does not sit alongside groundwater mismanagement as a parallel policy track; it compensates for it. Engineering intervention substitutes for the slower, politically complex task of reforming water provision, regulation and enforcement.

Critics point out a severe policy paradox: the giant sea wall directly clashes and overlaps with other National Strategic Programmes, such as the Ministry of Marine Affairs and Fisheries’ initiative to revitalise aquaculture ponds along the northern coast.

The project could also severely disrupt marine ecosystems, alter oceanographic dynamics – such as coastal currents, erosion, and sedimentation – and result in “ocean grabbing” by displacing coastal communities from their livelihoods.

The scale of the proposal is striking. Indonesian officials have discussed a barrier stretching hundreds of kilometres along Java’s northern coastline, from Banten to Gresik, with estimated costs reaching US$80b over two decades.

Financing Adaptation, Sidelining Alternatives

Jakarta has actively invited participation from both Japan and China, embedding the project within a wider strategy of external balancing in infrastructure financing. At this point, engineering considerations become intertwined with financing structures and strategic design choices.

Japanese involvement has historically emphasised technical feasibility, environmental assessment and long-term planning standards, often through development assistance frameworks. Chinese participation, by contrast, tends to prioritise speed, scale and state-backed construction capacity, frequently bundled with adjacent commercial development.

These differences matter because financing structures shape what infrastructure is expected to do. Large coastal protection schemes rarely remain confined to risk reduction; they generate opportunities for land reclamation, industrial estates, logistics corridors and real estate development. As these components are incorporated into project design, the function of adaptation shifts—from public protection toward asset creation and revenue generation.

In this way, geopolitical competition does more than diversify funding sources. It reinforces a bias toward large, capital-intensive interventions that are compatible with external financing, while sidelining reforms – such as groundwater regulation and water service expansion – that are less visible, less investable and harder to externalise.

The sea wall, therefore, reflects the environmental urgency as well as the political economy of how adaptation is financed.

If financing structures shape which forms of infrastructure are prioritised, they also determine which approaches remain marginal. Ecosystem-based measures, such as mangrove restoration, receive less attention not necessarily because they are ineffective, but because they generate fewer opportunities for large-scale investment, commercial bundling or geopolitical engagement.

Proposals for a 500-metre-wide mangrove green belt along roughly 500 kilometres of coastline – covering around 25,000 hectares – illustrate this contrast. At a fraction of the projected cost of the sea wall, such an approach could provide meaningful coastal protection while supporting hybrid livelihoods and blue carbon sequestration.

A dense mangrove buffer can reduce wave energy, limit coastal abrasion and stabilise sediment, while enabling silvofishery systems that integrate aquaculture with conservation.

However, its effectiveness remains context-dependent. In heavily urbanised or already submerged areas, land availability, ecological conditions and long-term maintenance constraints limit scalability.

Alas, the marginalisation of these alternative approaches highlights a broader pattern: adaptation strategies are selected more on how well they align with prevailing financing models and the demand for visible, large-scale intervention than on the basis of technical suitability alone.

Limits of Concrete Statecraft

The state has seen related dynamics before. The Jakarta Bay reclamation controversy revealed how coastal infrastructure can become entangled with oligarchic real estate interests, contested land use and the marginalisation of fishing communities. In such cases, infrastructure reorganises coastal space in ways that redistribute economic and political power.

The sea wall sits within a broader developmental trajectory. It follows the logic of megaproject-driven statecraft visible in the Ibu Kota Nusantara (IKN/Nusantara) relocation project and earlier in Jakarta’s own infrastructural expansion. In each case, large-scale construction functions as a demonstration of state capacity and modernising intent.

Yet this emphasis on visible infrastructure also obscures the underlying institutional conditions driving vulnerability.

The coastal risk is the outcome of fragmented governance across water supply, urban planning and environmental regulation. Responsibilities are divided across agencies with overlapping mandates and uneven enforcement capacity, making coordinated long-term groundwater management difficult to sustain.

The Netherlands is often invoked as a model of coastal management, but its relevance is frequently misunderstood. Dutch flood protection is underpinned by tightly integrated groundwater regulation, spatial planning, ecological management and centralised water authorities with long-term planning authority. The system works because institutional coordination is its foundation.

Indonesia’s coastal strategy is attempting to scale up the physical dimension of this model without its institutional preconditions. Yet the drivers of subsidence – fragmented water governance, uneven enforcement of groundwater restrictions and incomplete piped-water coverage – are precisely the elements that Dutch governance structures were designed to eliminate.

The result is not simply a weaker version of Dutch coastal defence but a different category of project altogether, one in which infrastructure is asked to compensate for institutional fragmentation rather than operate through it.

The giant sea wall retains strong political logic despite these tensions. Indonesia faces a rapidly intensifying coastal crisis, and visible state-led intervention carries strong domestic appeal. The project signals capacity and urgency in a context where slow-moving institutional reform is politically less legible.

But this is precisely the tension. When climate adaptation is framed primarily as an engineering challenge, it can displace attention from governance reforms that determine whether engineering solutions can continue to be viable. At the same time, as adaptation becomes financially and geopolitically valuable, it risks being shaped by incentives that extend beyond climate resilience.

The most plausible outcome is misalignment. The sea wall may succeed as a symbol of state ambition and as a vehicle for investment mobilisation, while doing less to address the structural drivers of subsidence and flood risk. In that sense, it becomes part of the system it seeks to stabilise: a large-scale intervention that manages symptoms while leaving underlying dynamics intact.

The sea wall project is therefore less a definitive solution to coastal collapse than a political settlement in concrete form—one that reflects the limits of governance reform, the pressures of geopolitical competition and the growing entanglement of climate adaptation with infrastructure-led statecraft.

As climate adaptation becomes more valuable financially, strategically and symbolically, the central question is whether the infrastructure built in the name of protection ends up reproducing the very vulnerabilities already visible along Java’s northern coast.

The views expressed are those of the authors and do not necessarily reflect those of STRAT.O.SPHERE CONSULTING PTE LTD.

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• TAGS:
• Indonesia
• China
• Japan
• Sustainability