As the tide rises, Indonesia struggles to save the living—and the dead

This article was contributed by Andra Lawrence Jackson, Samuel Lim, Hansraj Singh & Kyan Aw-Kay from 3E Full Geography 2022. 

DEMAK REGENCY, INDONESIA 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.

At the end of Ramadan last May, Timbulsloko residents visit the graves of their relatives in the 

flooded cemetery, reaching it via a long boardwalk. They live surrounded by seawater, which 

regularly floods their homes. When they die, they are buried at low tide.

“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.

As they prepare to add mud to the top of the cemetery to raise it above the high tide line 

once again, villagers mark the locations of the graves with bamboo sticks.

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.

Mulyono writes his relative's name on the temporary marker that will replace the 

tombstone while the cemetery is being raised.

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.

Left: As many as 500 people have been buried over the decades in 150 graves at the cemetery.

Right: An excavator dispatched by the local government begins digging mud from the seabed to 

elevate the cemetery. For the villagers of Timbulsloko, saving the cemetery preserves their 

connection to their past—and is a symbol of respect for their ancestors.

“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.

Villagers install a bamboo fence that will retain the mud added to the cemetery and keep it from 

washing away. The excavator worked for three days—but the villagers did most of the work to 

raise the cemetery themselves.

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.”

This article was originally published on National Geographic. Its inclusion on this website is solely for education purposes. 

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