The land is sinking so fast on the north coast of Java that villages and at least one cemetery are being drowned. Climate change is to blame—and overuse of groundwater.
To bury Mukminah last June, they had to bring in the dirt by rowboat. The cemetery was underwater in Timbulsloko, a village some 285 miles east of Jakarta, the Indonesian capital. On maps the village looks like it’s still on the north coast of Central Java, but the land around it has long since been taken by the Java Sea. The cemetery, a few hundred yards outside the village, had been submerged even at low tide since 2020. There was a dead rain tree in the middle of it, surrounded by dozens of headstones sticking out of the water.
Mukminah was in her early 70s when she passed away. She would have remembered, as surviving elders do perfectly, how green and prosperous their village once was. Paddy fields stretched as far as the eye could see. Villagers grew coconut trees, red onions, chilis, cabbages, carrots, potatoes.
“Whatever seeds you threw to the ground, they would grow,” recalls Ashar, the village leader. He’s lean and muscular, and only 39—but he remembers the better days too. The water has come on fast in just the last two decades.
The north coast of Java is sinking, and the sea is rising. In Jakarta, a city of more than 10 million, as much as 40 percent of the land is below sea level. But Demak Regency, the county that includes Timbulsloko, is one of the hardest hit parts of the coast. While global warming is causing sea levels worldwide to rise around an eighth of an inch a year, the land here is sinking as much as four inches annually. Demak is losing more than a thousand acres of land, about half a percent of its area, to the Java Sea each year.
In Timbulsloko, after crops failed in the 1990s—the rice turned reddish black—the villagers shifted to aquaculture, breeding milkfish and tiger prawns in brackish ponds. They had a few good years—but by the mid 2000s, the ponds too had been overtaken by the sea. Now the “mainland” is over a mile away, and the villagers travel there by rowboat. To stay dry in their houses they’ve installed wooden decks or raised the floors as high as six feet, such that they now have to bend over to enter under the low ceilings of their “dwarf houses,” as they call them. Of the more than 400 families that once lived here, around 170 are left.
The cemetery is one of the last things that connect them with their history.
The Muslim practice is to bury the dead as soon as possible. Seven men were tasked to prepare the burial ground for Mukminah. They dug into the mud for about an hour with hoes, building a dike around the hole while trying to drain it. Their hoes struck the bones of an earlier burial; they kept digging. Shirtless and soaked below the waist, they dug until the high tide filled the hole.
Mukminah was buried seven hours later, in the dead of the night, when the tide had ebbed again and the water in the hole was only ankle-deep. She was buried under more than a ton of loose, light-brown soil that the men had rowed over from the mainland in white bags.
“You can’t bury the body with mud and water,” Ashar says. “So we have to buy fresh soil.”
“It isn’t easy to live here, as you can see,” he goes on. Ashar can’t afford to leave, because he can’t sell his property; nobody wants to buy a dwarf house in the middle of the sea. The elders, on the other hand, don’t want to leave. They want to live with their childhood memories, close to their ancestors.
After the funeral, the villagers pleaded with the Demak government for help. In the fall, the local public works department sent workers with a backhoe, who scraped enough mud off the shallow seafloor to raise the whole cemetery five feet. That will buy the living and the dead in Timbulsloko a little more time.
CITY OF THE SAINTS
Demak Regency today has 1.2 million inhabitants, a small fraction of Jakarta’s population. But in the late 15th century it was an independent sultanate, the first Muslim state on Java, one that dominated the northern coast, as well as southern Sumatra. The Grand Mosque, built by the early ruler Raden Patah as a center of Islamic teaching, still stands at the heart of the town of Demak. More than 500,000 pilgrims a year visit the tombs of the Wali Songo, or nine saints, who helped spread Islam on Java—Demak is known as the City of the Saints.
The North Coast Road, built in the 19th century along the length of Java by the Dutch colonial government, runs right through Demak. It’s still a major artery, with around 400 trucks passing every hour. Factories along the road produce everything from fertilizer to electronic devices to textiles to processed food. But in recent years tidal floods have repeatedly inundated the road, causing severe congestion and millions of dollars in economic losses.
There are several distinct causes of the floods—and of the fact that Central Java has lost some 20,000 acres of land, according to satellite data, 8,000 of them in Demak. Sea level rise caused by climate change is the least important contributor.
Java’s northern coastal plain consists of dozens to hundreds of feet of alluvial sediment, deposited over thousands of years by rivers flowing to the sea from the North Serayu Mountains. The sediment tends to sink as it compacts under its own weight, explains Aron Meltzner, a geologist at Earth Observatory of Singapore, Nanyang Technological University.
“This is a very natural process,” Meltzner says. “But because the river is bringing more sediment, as the existing sediment compacts, more mud gets built on top and that’s why the delta stays above water.” At least that’s what used to happen: As the rivers jumped their banks during annual floods, and as their channels migrated back and forth through the soft mud, they spread the sediment evenly across the plain.
Yet the flooding also threatened modern cities. In the late 19th century, the Dutch built canals, levees, and sluice gates as flood controls in every major city on the Java deltas, especially in Jakarta and Semarang, the capital of Central Java.
Today the levees and concrete embankments keep the rivers from flooding—but they also prevent them from spreading sediment across the plain. Instead it’s deposited at the bottom of the river or sent straight into the ocean, robbing the land of new soil. That’s one reason the north coast of Java is sinking into the sea.
“Even in the absence of sea level rise, just the fact that we channelized the rivers and prevented them from migrating, means that the natural process has been interrupted,” Meltzner says.
DRINKING WATER, SINKING LAND
Heri Andreas, a researcher at the Bandung Institute of Technology who has spent more than a decade studying the sinking of the north coast, says another factor is at work: massive groundwater extraction, which is causing the sediments to compact and the land to sink faster.
In Demak Regency alone, as of 2014, there were almost 250,000 wells bored to various depths, ranging from 82 to 500 feet, in an area the size of Berlin, Germany, or Fort Worth, Texas. There are probably more by now; 2014 is the latest year for which government data are available. Most of the wells are private. But the Demak Water Supply Agency, part of the local government, has also drilled deep wells at four sites. It uses them, along with water from the Jajar River, to provide tap water to more than 58,000 households in 59 villages, out of a total of 249 in the regency. In 2020 that system distributed at least 9.7 million cubic meters of groundwater.
For more than a decade, the local government has promoted groundwater extraction as the cheapest way to meet the pressing demand for drinking water and sanitation. With groundwater, there’s no need to build dams, reservoirs, aqueducts, and complex water treatment systems—it doesn’t require treatment. But using it here still exacts a high price.
“People, especially the government, keep blaming sea level rise as the main cause” of the loss of land in Demak, Andreas says. “But our conclusion is that the main culprit turns out to be decades of groundwater exploitation.”
Demak’s public tap water network still only serves a small fraction of the regency’s population, and it doesn’t reach Sayung District, which includes Timbulsloko and is where the worst land subsidence is taking place. In the village of Sayung, some residents have drilled more than a dozen deep wells to supply the entire village of almost 2,000 families. The water is stored in huge elevated tanks and costs around $0.20 per cubic meter, cheaper than the service provided by water companies.
“It’s been a good business, with good profit,” says Munawir, the 41-year-old village leader, who spends about $13 per month himself for water service. The 49-foot-deep well his father drilled in his backyard in the 1980s is unusable now, contaminated by seawater.
“Of course we hope that the government can provide a tap water network to prevent the sinking” of the land, Munawir says. “But it will also kill the already established local water business.”
The local government says drilling deep wells requires official permits and that unregistered wells will be shut down. But it hasn’t closed any wells in recent years. Qomarul Huda, the head of the Demak Water Supply Agency, declined to comment on groundwater extraction. He blamed water shortages in the regency on farmers who draw too much from the Jajar River for irrigation.
As Demak’s population and industry’s water demands continue to grow, groundwater extraction will likely increase too. The reason is simple: No one is willing or able to invest the tens of millions of dollars that would be needed to build reservoirs, treatment plants, and distribution networks to provide the region with an alternative water supply.
FIGHTING THE TIDE
For a decade, the Central Java provincial government and NGOs have been struggling to protect the coast from erosion. The government claims to have planted more than three million mangroves covering 900 acres across Central Java since 2011, to absorb the energy of the waves and tides. The plan is to cover almost 2,000 acres by 2023.
Environmental NGOs working with local fisherfolk, meanwhile, have built miles of bamboo fences just offshore in Sayung District. The fences act as permeable breakwaters that trap sediment stirred up and transported by ocean waves, especially during monsoon storms. The fences are cheap and meant to be temporary—the idea is to trap just enough sediment to allow mangroves to take root, which will then act as natural breakwaters—but they are attacked by wood-boring organisms, collapse easily, and sometimes have to be rebuilt.
“We have yet to feel the impact of this coastal engineering,” says Fadholi, a 36-year-old fisherman hired by an NGO to maintain the sediment trap in Bedono, another village in Sayung district. “We haven’t seen sediment build up here because the current keeps washing it away.” The fences do act as breeding grounds for green mussels, however, which locals collect and sell.
Researchers at Diponegro University in Semarang have tested several other methods of coastal protection, some successful. At Timbulsloko in 2012 they built a seawall of stacked concrete cylinders along about 500 feet of the former coastline. Within two years enough sediment had built up behind the wall to grow mangroves—which today are more than 10 feet tall.
But concrete is too expensive to be a large-scale solution, says Denny Nugroho Sugianto, an oceanography professor at Diponegoro. As a more practical and more environmentally friendly approach to coastal restoration, Sugianto advocates permeable breakwaters of bamboo and PVC pipe, which is more durable but still cheap.
“Yet we haven’t solved the problem of sinking land,” he says. “So no matter how many breakwaters we build, they won’t be successful.”
The national government, as part of a strategic effort to save vital assets and industrial zones, is building a combined highway and sea wall from Semarang to the town of Demak, a distance of some 17 miles. It’s expected to be finished in 2024 at a cost of $532 million. The bad news: Only small portions of two villages in Sayung’s coastal area will be protected. The move angers residents of villages outside the wall, such as Timbulsloko and Sayung, who feel they are being left to drown on their own.
Central Java Governor Ganjar Pranowo, a tall, 53-year-old man with graying hair and a boyish smile, acknowledges the limitations of the planned sea wall. He says the government simply can’t afford to build anything like the ones in the Netherlands, to protect the entire north coast of the province or even all of Demak Regency. Huge pumping stations would be needed to evacuate floodwaters from behind the wall into the sea. The whole system would require extensive maintenance indefinitely. The government simply doesn’t have the money, Pranowo says.
What should the people in the flooding villages do?
“The last resort is to relocate to a safer place,” says Pranowo, who’s in his second term as governor and is expected to run for president in 2024. “Or if they insist on living there, they have to adapt to the environment by building stilt houses, for example. If they want their land back just like the old times, it’s impossible. It’s drowned now.”
COMMUNING WITH GHOSTS
There is no paddy field left in Mondoliko hamlet, another one of the drowned villages in Sayung District, and one of the most secluded. To get there, the locals walk a mile along a narrow cement path that crosses open water and is itself always submerged; at high tide the water is as much as thigh deep and the path is invisible. At the end of the path, the residents of Mondoliko continue another two miles in boats, passing hundreds of acres of green mussel farms. In the hamlet itself the road is flooded and so slippery that they walk barefooted.
“Villagers had raised the level of the road about 30 centimeters [nearly a foot] earlier this year,” says Kusmantri, 46, who works in a roofing factory in Semarang. “It’s drowned again.”
In his youth, Kusmantril helped his father in a paddy field that has since vanished. After his father died, Kusmantri became the backbone of his large family. He dropped out of junior high and began working odd jobs, finally landing the job at the factory. Now he has a wife and two children himself. A few years ago he bought a small motorboat, so he could also work nights as a mussel farmer and fisherman, catching bluespot mullet, shrimp, and crabs. He sells his catch to neighbors and sometimes to a commercial broker.
Kusmantri has lived in this hamlet all of his life, and he desperately wants to move out. He has raised the floor of his house three times since 2013, a total of five feet, but seawater keeps coming in during the highest tides. Apart from a wooden bed frame and a small side table to hold his TV, the place is relatively empty. The green paint on the cracked walls has started to peel off, exposing the bare cement.
“When you go home from work and you just want to get rest, you can’t do it here,” Kusmantri says. “You have to mop and dry the floor first before you can rest. We’re just tired of living like this. It’s draining our energy and mind.”
Kusmantri has begged the provincial government to relocate the hamlet. Though officials have heard his plea, there is no sign of it happening. There are only 40 families left in Mondoliko, down from 170 historically. The abandoned, dilapidated houses give it the feel of a ghost village. But the call to prayer still rings out from the mosque.
In Central Java the Muslim tradition is to visit the cemetery every Thursday, late in the afternoon, to deliver prayers to the deceased. One recent Thursday Khusnumarom, a 16-year-old high school student, made his way to the cemetery in Timbulsloko.
Dressed in a traditional white shirt, black songkok cap, and dark gray trousers, he walked barefoot on a narrow, six-foot-high boardwalk, nearly two miles long, that was built by the residents earlier this year to replace the vanished roads. He made a right turn down some wooden stairs and crossed a creek on the slippery, submerged road; the tidal flood reached knee deep. But his steps were confident. On the other side he climbed back onto the boardwalk and continued on.
When he reached the underwater cemetery, the shadows had already begun to fall. The dead rain tree and the headstones were silhouetted against the deep orange sky. Khusnumarom found the grave of his grandmother, Mukminah. He raised his hands and began to pray.
Khusnumarom knows how his village once was through bedtime stories, including the ones Mukminah told him. Those memories will die with the older generation, and sooner or later the stories too will fade. Like many of his fellow youths, Khusnumarom doesn’t plan to stay in Timbulsloko.
“I know what this village looked like,” he says. “But we see and experience what it has now become.” He’ll look for a job in the city once he graduates. He wants to be a software engineer.
