The Giant Sea Wall would be a perfect disaster, destroying fish spawning grounds and local and migratory waterbird habitats.

A person walks on a cracked seawall on May 7, 2024, in Kalibaru, Cilincing, North Jakarta. Residents of the area fear that the wall, which was built to protect the area from waves and tides, could collapse at any time. (Antara/Aprillio Akbar)

Every government seeks a large-scale project to define its legacy, as seen with Indonesia's Mega Rice Project (MRP), Merauke Integrated Food and Energy Estate (MIFEE) and the Nusantara capital city project.

Recently, the massive Giant Sea Wall project has emerged, planned for the northern coast of Java Island. Classified as a national strategic project, the sea wall construction is valued at an astonishing Rp 1,750 trillion (US$104 billion) about half the current state budget, and would span roughly 700 kilometers of coastline.

President Prabowo Subianto announced the plan following a visit to China early last month and later mentioned it in his maiden United Nations General Assembly speech, citing Indonesia's concern over sea-level rise along Java's northern coast (Pantura). While he quoted a smaller figure (480 km), the project raises numerous critical questions regarding its location, technology and execution.

The Giant Sea Wall, touted to protect 50 million people and many industrial areas, falls squarely into the category of gray technology, infrastructure based on cement and concrete. This contrasts sharply with green infrastructure, which prioritizes environmentally friendly, ecological solutions.

The Science 20 (S20) engagement group of the Group of 20, to which Indonesia belongs, has prepared a Call to Action for the upcoming G20 Summit in Pretoria, South Africa, in November.

In this statement, the S20 urges governments to reduce their reliance on gray technology for climate action. This is because massive concrete foundations disrupt groundwater availability, and the fossil fuel-dependent cement industry contributes significantly to the greenhouse gas emissions that cause global warming and rising sea levels.

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Conversely, green technology, such as mangrove greenbelts, should be maximally utilized. Mangroves offer a highly effective, long-term ecological solution that is pro-job and pro-poor, as they boost the economy of local communities dependent on aquaculture and fisheries.

The idea of China funding Prabowo’s Giant Sea Wall is ironic, given the country’s lack of experience compared with the Netherlands and its current large-scale national program, championed by President Xi Jinping, to restore its western and eastern coastal areas using an ecological approach to revive waterfront cities and greenbelts as migratory bird habitats.

In fact, Indonesia has already initiated a massive mangrove restoration effort, having borrowed $300 million from the World Bank to restore 600,000 hectares within a short timeframe under the previous Onward Indonesia Cabinet. The fate of this massive program remains largely unknown, and the institution tasked with implementing it, the Peat and Mangrove Restoration Agency, has been liquidated.

It would be logical to redirect the remaining World Bank funds, originally intended for nine provinces outside Java, to restore mangroves in the heavily affected Java’s north coast region instead. Lawmakers representing the area should utilize their aspirational funds to listen to coastal voices, proving their role as people’s representatives.

The assumption that Java does not need priority is incorrect, as the island is already "tilting" northward due to intense population pressure and severe land subsidence. On a local scale, subsidence in coastal wetlands is exacerbated by the collapse of mangrove root systems that have been cleared for other uses.

A massive wall is not the solution for these areas; it would hinder the natural circulation and mixing of seawater and freshwater in coastal areas, a critical requirement for mangrove growth in the devastated green belt. The Giant Sea Wall would be a perfect disaster, destroying fish spawning grounds and local and migratory waterbird habitats.

The repeated failures of megaprojects like the MRP and MIFEE, which typically share a top-down, strategic labeling but end in tragedy, must serve as lessons. If the Giant Sea Wall megaproject is to proceed, the government must consider several fundamental aspects.

First, combine engineering and ecological approaches, restoring the integrity of mangrove ecosystems across the devastated Pantura region. Redirecting World Bank loan funds for mangrove rehabilitation, with legislative support, is the most logical choice.

Second, prioritize national private sector involvement that possesses the technological capabilities and can manage large funds, thereby freeing up public funds for social safety nets in food, health and disaster mitigation sectors.

Third, involve young professionals to give the millennial generation ample opportunities at home, allowing them to play a key role in large-scale national projects.

Fourth, adopt the role of regulator and impartial referee, rather than executor prone to conflicts of interest that breed corruption and leakage. The government must be vigilant against rent-seekers.

These four principles could be upheld by an authority agency with full multi-stakeholder authority, allowing the project to potentially be completed within two five-year National Medium-Term Development Plans (RPJM) over a 10-year period.

Daniel Murdiyarso,

The writer is president of the Indonesian Academy of Sciences. The views expressed are personal.

Tulisan ini pertama kali terbit di Harian The Jakarta Post 11 Maret 2025