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Homes affected by erosion
Java, Indonesia

Parts of northern Java slowly disappear as rising seas exact their toll

West Java, INDONESIA _ The milkfish ponds that have dominated the northern coastline of Indonesia’s most populous island since the 1970s are now slowly fading away, retreating under the relentless onslaught of pounding sea waves.

In Muara Gembong, in the West Java district of Bekasi just northeast of the capital Jakarta, dozens of such ponds have been engulfed by the sea, and the roughly 2,000 families whose livelihoods depended on them have had to retreat inland to higher ground.

Mangrove shoots have retaken areas where homes once stood. The rare signs of life on the shore now are only mud crabs and mudskippers.

“Residents’ houses located near the shores have been swept away by the waves,” Rahmat, 30, from Kampung Beting, a hamlet in the ironically-named Happy Beach village (Pantai Bahagia) said at the end of November last year.

His own house, once a safe four kilometers from the sea, is now just two kilometers from the threatening waves.

“It seems that from year to year, [the sea] is approaching more and more,” he said.

Population figures from Indonesia’s Central Bureau of Statistics reveal how Pantai Bahagia shrank from 8,166 residents in 2014 to 7,161 residents two years later, in 2016.

The milkfish ponds, though shrinking, still cover 7,344 hectares of land area in Muara Gembong, leaving only 379 hectares of protective mangrove forests that help slow erosion, according to an ecological footprint analysis conducted by the Fishery and Marine Faculty of the Bogor Institute of Agriculture in 2014. 

Coastal erosion has forced people to relocate away from the fish ponds at the same time that fish catches have been declining, forcing many fishermen to look for other ways to survive.

Seventy-eight-year-old Jumin from Muara village has watched as the house he has lived in for years is slowly swept away by the waves.

“Before ceramic tiles were common, I had covered the floor with cement tiles,” he said. “Then it got submerged. I scrapped the floor and replaced it with the ceramic tiles, but once installed the floor got submerged again.”

Friends and family have repeatedly urged him to move out, but Jumin remains obstinate about not abandoning his only prized possession. “I will wait until everything is really swept by the waves,” he said.

Jumin’s misfortune is no secret.

“The sub-district chief, the village chief, the district chief and even Mr. [President] Jokowi came here [the president in early 2019.] But things have not changed,” Jumin said.

Like other local residents, he had high hopes that the government would fund construction of a wall along the coast of Muara Gembong subdistrict to halt the erosion, but so far it hasn’t happened.

“There was indeed a plan to build stone wave breakers but not in the one or two years to come,” Muslim, the Muara Gembong sub-district secretary, said without giving details on when the project might be started.

At present, the sub-district’s priority infrastructure projects are building bridges and smoothing village road access, Muslim said.

(See original story: “Fishermen in Muara Gembong: Kebo Shot in Kampung Dolar”)


Sea coverage in Java island 1984 to 2018. Data source: The European Commission’s Joint Research Center (EC JRC) processed by Resource Watch


Similar stories of loss have played out in Demak, Central Java.

In Tambaksari hamlet the number of households has gone from around 200 in the 1990s to just seven, and Bedono village, which, with its seven hamlets had once been the biggest village in Demak district, is now the smallest.


Demak is the second-worst erosion-hit district in Central Java, having already lost 2,218 hectares of coastal land to the sea, according to the Central Java Marine and Fishery Office.

The loss of the fish ponds is just the beginning. The loss of livelihoods, homes and the destruction of coastal ecosystems are some of the more serious threats this region will face in the years ahead.

Already almost all the homes around Edi Saktiono’s house in Tambakrejo hamlet have been built on top of houses that were washed away by the encroaching sea.

Slamet Riyadi, who heads the local neighborhood administrative unit, blamed the rapid erosion on the expansion of Tanjung Mas Harbour in the 2000s. The port’s expansion was facilitated by sand mining that was put toward land reclamation.

Fendiawan Tiskiantoro, who heads the Central Java Marine and Fishery Office, said the erosion issues cannot be separated from the development activities in Semarang, which along with Demak has seen its shoreline among the worst hit by rising sea levels in Central Java.


“Theoretically, if we build one kilometer into the sea, the impact can be felt in nine kilometers on both sides,” Fendiawan said. “This is because the sea current will be trapped by the construction and thus erode the land around it.”

Indonesia’s Geospatial Information Agency does not have concrete data on the extent of land along the North Coast of Java that has been eroded. Rather, it relies on estimates from around the 2000s.

Regardless, the local and central governments have taken some measures to stop it. They’ve planned concrete barriers along the shore and encouraged communities to plant and preserve mangroves. But most of those measures have been unsuccessful, including an 825-meter long embankment that came at a cost of Rp156 billion (US$10 million) and is now underwater.

A complex problem

Jafron Asiq Hidayat, a researcher from Diponegoro University in Semarang, thinks the erosion happening on the northern coast of Central Java is particularly threatening due to the slow build-up of new land.

Erosion is usually correlated with accretion, the building up of sediment over time, Jafron said. In Central Java, this accretion takes place much slower than erosion – about two times slower, in fact.

Erosion graphic
Six issues affecting sea-level rise: Land accumulation, wind, sedimentation, related environmental impacts (such as mangrove damage or loss of fisheries), land subsidence and embankments. The severity of erosion in the coastal region also greatly depends on the surrounding environmental health.

Jafron said that the accelerated erosion among the 13 districts and municipalities on the northern coast of Central Java is linked to hydro-oceanographical changes, such as ebbs and tides, currents and waves.

Hydro-oceanographic changes can be influenced by global warming as rising water temperatures cause seas to expand, producing a rise in sea levels, Jafron said.

“Therefore, the problem in Central Java is complex. Infrastructure development and natural factors are intertwined,” he said.

(See original story: “North Coast Swallows Central Java”)

Response lacking as sea-level projections grow more extreme

In Tuban, East Java, the sea is slowly eating up the shore as well. In 2016, the sea encroached on 13,682 square kilometers of land. The following year, another 12,882 square kilometers of land was damaged.

The impact has been great for two dozen families in Boncong Village, each of which suffered material damages of around Rp20. 5 million (US$1,440) when waves amplified by strong winds hit their homes, according to an assessment by the Tuban District Disaster Mitigation Agency.

Yet the village government response has been minimal, limited to sending sandbags to residents to prevent the sea from reaching their homes.

Umi Kalsum, who heads the Fishery department at the Tuban District Fishery and Livestock Office, said her office had sent 79,500 seedlings of cemara udang, a coastal pine tree variety, to communities along the Tuban coastline between 2016 and 2019 to stave off future damage.

The cemara udang is a coastal plant that like mangroves can serve as wave breakers, protecting the coastline from encroachment, severe weather and tsunamis.

Mangrove protection graphic
Three ways other than planting mangroves to control erosion.

Unfortunately, Umi said, programs to mitigate erosion were hard to implement because of the existing overlap in authorities.

For people living from Bancar district up to Jenu, however, the situation could get even worse if something isn’t done, and soon.

According to an analysis by Climate Central, a scientific institution based in the US state of New Jersey, seawater levels will be 0.5 meters higher than predicted last century.

Climate Central further projected that sea levels could be expected to rise by between 20 and 30 centimeters by 2050, submerging settlements inhabited by around 23 million residents in Indonesia’s coastal areas, including Jakarta.

If that happened, coastal areas in Tuban districts could disappear under the sea.

But the impacts of erosion will be different along the north coast of Java because there are differences in land surfaces along the coastline, said Adi Purwananda, a researcher in oceanography and global climate change from the Indonesian Institute of Sciences. "Depending on the topography, the height of the land surface in each city ... it can't be generalized that all have the potential to sink, for example in 2050. It's not that easy," he said.

In a 2013 research paper titled “Identification of Areas Prone to Abrasion in Coastal Tuban District,” Veranita Hadyanti Utami, an urban and regional planning researcher from the Technology Institue of Surabaya, wrote that at least 3,600 square kilometers of coastal area in Tuban had been eroded between 1993 and 2009. Erosion, on average, claimed between five to six meters of land every year.

Historically that hasn’t always been the case. Research conducted by M. Arif using the digital shoreline analysis system based on Landsat satellite imagery between 1964 and 2017, showed that accretion was actually higher than abrasion due to the construction of massive infrastructure projects, such as the jetty for the special port for PT Semen Gresik, a special harbor for PT Holcim, and the special harbor for Trans-Pacific Petrochemical.

But this massive infrastructure building has damaged the coastal environment, posing risks for future environmental disasters.

Tarsan, a fisherman born in 1972 along the Tuban coast, said his area currently feels safe. There is a 10-meter deep foundation to keep the highway standing, protecting the land area from the sea. But concrete is still concrete, which will slowly erode, he said. Avoiding abrasion is not just building a foundation.

(See original story: “Earth’s Guardians Threatened to Disappear”)


Storigraf, a collection of journalists, along with traveled along the north coast of Java to document the latest conditions for an eight-part series on erosion that first appeared on in January. The reporting team visited six coastal points in three provinces in Java: Muara Gembong in Bekasi (West Java); Demak and Semarang (Central Java); and Tuban and Pasuruan (East Java). The stories capture the on-the-ground impact of sea-level rise and pair it with data and visuals to show the true effects of global climate change.

  • Reporters: Alfian Putra Abdi, Ahmad Zaenudin, Andya Dhyaksa, Bonardo Maulana Wahono, Fajar Wahyu Hermawan, Muammar Fikrie, Ronna Nirmala, Rommy Roosyana
  • Head of project collaboration: Ronna Nirmala
  • Photographers: Bismo Agung Sukarno, Wisnu Agung Prasetyo
  • Videographers: Aditya Nugraha, Riitya Nugraha Maelite
  • Data: Yandi M. Rofiyandi
  • Data visualization: Irma Garnesia
  • Infographic: Antyo Rentjoko

Reporting for this project was supported by a grant from Internews' Earth Journalism Network (EJN) and Resource Watch , an international research institute that focuses on issues of future sustainability.

Banner image: Residents' homes affected by erosion in the Bedono area, Sayung, Demak, Central Java pictured on November 13, 2019 / Credit: Wisnu Agung Prasetyo