Zane Goebel, University of Queensland; Sonia Roitman, University of QueenslandAND Udiana Dewi, University of Sydney
Indonesia plans to build a “giant sea wall”, more than 500 kilometers long, to protect the northern coast of Java from rising sea levels.
The proposal includes a large lagoon behind colossal concrete wallraising significant questions about the feasibility and cost of such a gigantic project.
Indonesian civil society groups say the sea wall could encourage more sand mining, degrade mangroves and affect the livelihoods of fishing communities. It is feared that the project will exacerbate the existing ecological destruction caused by industrialization. While desperate to avoid flooding, these groups do not see a wall as a solution.
Indonesia has been significantly affected by climate change, often in the form of heavy and regular flooding.
So what’s the best way to respond?
What is Indonesia proposing?
of sea wall plan is established as a major economic project on the north coast of Java. It will cost at least 80 billion US dollars and takes decades to build. Building is scheduled to begin in September 2026.
of sea wall will be supervised by several government agencies and subject to Review by the Indonesian Corruption Commission (KPK). Whether such scrutiny will be effective is an open question.
The massive cost is planned to come from provincial and national budgets, along with public-private partnerships with places like United Arab Emirates. There are concerns about who will pay the huge bill for the long-term maintenance of the sea wall.
The rising sea
Indonesia has a long the history of flood management by building infrastructure such as canals and dams, reclaiming land and deepening or diverting rivers. But such solutions often either make the problem worse or are only stopgap measures before sea-level rise overtakes land.
Indonesian MEDIA AND academics are pushing for a different strategy. This will include consultation with affected communities, integrated coastal management, wastewater improvement and river cleaning so that the future lagoon does not become a low-oxygen moat behind a wall.
For Australia, Indonesia’s closest neighbor and a key strategic and economic partner, how Jakarta manages this project will shape regional security. Historically, the Department of Foreign Affairs (DFAT) has worked closely with its Indonesian counterpart (BAPPENAS) on infrastructure such as water projects.
Failure to properly consult Indonesian stakeholders could lead to political consequences, while inaction could lead to food insecurity as vast tracts of rice fields become saline. Both create a less stable Indonesia, something Canberra wants to avoid.
An island under pressure
On the northern coast of Java – the world’s most populous island and the economic heart of Indonesia – the risk of flooding is driven by landslides and land use.
Subsidence (gradual submergence of land) and associated coastal erosion are common in Java, caused by a variety of factors such as excessive and unregulated groundwater extraction, building encroachment, mangrove deforestation, seawall construction, and soil moisture increases.
In our latest researchwe show the ways in which different levels of government communicate these problems change the way people understand these messages, potentially undermining imperatives to reduce groundwater extraction.
What does the evidence show?
The last one modeling suggests that offshore structures can reduce storm surge heights in some locations, but results varied by location and local underwater environment. These types of coastal adaptation projects have historically been sites of political argument and corruption.
our work in progress with Indonesian researchers in three villages in Kendal, Central Java, shows how flood defenses such as seawalls, raised roads and house grants can partially address the risk, but not solve it.
Grants of around A$2,000 helped some families put up floors, walls and roofs, but rarely covered the full cost. Poorer families sometimes refused as they understood the burden of co-financing.
Meanwhile, raised roads and flooded walls channeled water into low-lying houses nearby. This reshaped lifestyles, neighborhood interactions, and community dynamics. We also recorded saltwater intrusion into productive land that had previously avoided regular tides.
In short, works that do not also address the causes of decline can redistribute harm and entrench inequality. They may also affect one of the stated reasons for building the giant sea wall: addressing Food Security of Indonesia.
Can this seawall work?
The better question is not “wall or no wall,” but whether it is possible to build a giant sea wall that works as intended.
If it is possible to regulate and implement groundwater extraction, river cleaning and coastal works design with local communities, the unintended consequences of flood infrastructure can be minimized.
With these reforms, Java’s giant seawall could be a useful part of a broader adaptation portfolio. Without them, it risks becoming an expensive folly.
Zane Goebel is Associate Professor, Indonesian Studies, University of Queensland; Sonia RoitmanAssociate Professor in Development Planning, University of Queensland; AND Udiana Dewiresearch associate, University of Sydney
This article was reprinted from Conversation under a Creative Commons license. Read on original article.
