The good news: People are finding ways to slow and even reverse that sinking.<\/p>\n
As land returns to higher levels, flooding in many of these places will stop. Wells will continue to provide water instead of running dry. And innovative ways of fighting subsidence are helping to return nature to cities and surrounding areas.<\/p>\n
![\"A](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2025\/10\/1440_sinking_cities_flood_Jakarta.jpg\")
An Indonesian boy plays with his boat on a street that floods every morning during high tide in Jakarta. The flooding is due to the ground subsidence in this city. In some places there, the land has sunk as much as 25 centimeters (10 inches) per year.Ed Wray\/Stringer\/Getty Images News<\/p>\n
People \u2014 a growing problem<\/p>\n
Although earthquakes can cause land to abruptly sink, such natural events aren\u2019t the main cause of subsidence. People are. Or rather, our need for underground resources, especially water.<\/p>\n
Most fresh water on Earth is locked up as ice. Just one percent of the world\u2019s fresh water exists in rivers and lakes. The rest of that liquid water lies beneath the surface. It\u2019s known as groundwater<\/a>.<\/p>\n In many parts of the world, people drill down into aquifers<\/a> to pump that water out. It\u2019s an important source of water for millions of people. But in some places, that pumping is causing the land to sink.<\/p>\n It\u2019s a particularly big problem for large cities. The more people who live there, the more water they\u2019ll need to pump from the ground.<\/p>\n Not all cities sink equally fast. Geology plays a role, too, notes Leonard Ohenhen. He works at the University of California, Irvine. As a geodesist (Gee-AH-duh-sizt), he monitors and measures the Earth. \u201cSome cities sit on solid, hard rock that barely compresses,\u201d he says. \u201cOthers are built on thick layers of clay, sand or sediment that can compress easily.\u201d<\/p>\n Cities atop sediment are most likely to sink.<\/p>\n Ohenhen\u2019s team showed subsidence is a growing issue for cities across the United States<\/a>. They looked at the 28 most populated cities, many of which are inland. Their estimates suggest that at least 20 percent of the urban area is sinking in each of those cities, mainly due to groundwater pumping. In all, some 34 million people are affected. The researchers shared their results May 8 in Nature Cities.<\/p>\n Let\u2019s learn about Earth\u2019s secret stash of underground water<\/a><\/p>\n Subsidence comes with real, but often invisible, problems for the built objects that support a city. Think highways, railways and bridges. These \u201ccan crack or break when one section sinks more than another,\u201d Ohenhen says. Water and sewer lines can break as the land beneath them shifts. And buildings, when not constructed properly, can begin to break apart. Ohenhen\u2019s team found that in the U.S. cities it surveyed, more than 29,000 buildings are located in areas facing a high or very high risk of damage.<\/p>\n New construction can boost subsidence, says Pei-Chin Wu. She\u2019s a geologist at the University of Rhode Island in Kingston. To improve safety during construction in areas with soft soil, workers pump out water before adding the foundation for a new building.<\/p>\n Afterward, she says, they don\u2019t usually replace the water they\u2019d taken out. So the area subsides.<\/p>\n Many natural underground stores of freshwater are shrinking<\/a><\/p>\n Wu grew up in Taiwan\u2019s capital city, Taipei. It sinks and rises through the seasons. The whole city subsides during the dry season, as people pump out groundwater. \u201cWhen the rains come \u2014 and when the water level goes up \u2014 it will recover,\u201d she says.<\/p>\n The rains filter down into deep aquifers under the city. This pushes the land up again. The process doesn\u2019t happen everywhere, though. In places where there\u2019s been lots of construction, the ground never fully recovers.<\/p>\n Wu uses satellite data to study subsidence in coastal cities around the world. Those satellites bounce a signal off the land. Computers calculate the distance to the ground based on how long it takes for each signal to return. This shows the height of the land. By comparing repeated measurements for the same site, geologists can detect small changes in height over time.<\/p>\n In a 2022 study, Wu found that subsidence is a bigger problem, globally, than people had realized<\/a>. And it\u2019s been happening fastest in southeast Asia. Why? Cities there are growing quickly.<\/p>\n Subsidence is slowing in many cities, too, she found. It\u2019s still ongoing, but the rate of fall is not as fast as it was 10 years ago. That\u2019s thanks to the removal of less groundwater.<\/p>\n But not every city is slowing. In some cities \u2014 and smaller areas within many cities \u2014 the land continues to drop. This makes these areas more likely to flood.<\/p>\n<\/p>\n Urban sites in many parts of the world are being designed to absorb water, rather than let it run off. This can have many payoffs for both city dwellers and the environment, as this video shows.<\/p>\n Returning water to the ground<\/p>\n In mainland China, flooding has become a big problem. So has drought. Northern cities often get little rainfall. Those in the south can get way too much. So China developed a sponge city plan to balance the two.<\/p>\n Sponge cities<\/a> use green roofs (covered by grass or other plants), permeable pavements and other features to get water off of streets as quickly as possible, explains Michele Lancia. He works at the Eastern Institute of Technology, Ningbo, in China. As a hydrogeologist, he studies how water interacts with rock and soil.<\/p>\n In south China, these features protect people from flooding. In the north, collected water can be \u201cstored, purified and reused,\u201d he says. The goal is the \u201ccollection and reuse of 65 to 100 percent of the urban rainfall throughout China.\u201d<\/p>\n Managing water use \u2014 and reuse \u2014 could also help prevent future subsidence. The key is getting water into aquifers. This process is known as recharging. But China\u2019s current system isn\u2019t designed to do that.<\/p>\n Lancia is exploring new ways to recharge aquifers. Where successful, it could reduce flooding while ensuring water is available. \u201cThe sponge city concept will be more and more effective in the future,\u201d he predicts. It should save lives as the climate continues to change<\/a>.<\/p>\n China isn\u2019t the only place where flooding and water supply are an issue. In Virginia, in the United States, the Hampton Roads Sanitation District (HRSD) hopes to address both problems \u2014 and reverse subsidence along the way. They developed the Sustainable Water Initiative for Tomorrow, or SWIFT<\/a>, program. SWIFT aims to return wastewater to the ground. First, the water must be purified until it\u2019s clean enough to drink. Then HRSD pumps it deep underground into what\u2019s known as the Potomac Aquifer.<\/p>\n \u201cBack in [the] early 1900s, you\u2019d put a well in the Potomac Aquifer,\u201d says HRSD hydrologist Dan Holloway. \u201cWater would come out of the well above your head. You wouldn\u2019t need a pump. You\u2019d need a valve\u201d to shut it off. \u00a0<\/p>\n That water pressure dropped over the past century as people removed more and more water from the aquifer. Wells slowed from gushes to drips \u2014 then to nothing at all. People finally had to start pumping. The level of the water in the aquifer has since dropped about 38 meters (125 feet).<\/p>\n Pumping created another problem: salty groundwater. Fresh water naturally flows downhill from the rolling hills of central Virginia out toward the sea. That fresh water pushes out toward saltwater, Holloway explains. In the past, that flow has kept the groundwater largely salt-free.<\/p>\n Holloway likens it to a bed sheet pulled tight at a sloping angle. A marble on the sheet \u201cwill always roll downhill.\u201d But a groundwater pump makes a hole in the water level around the pump. The more that is pumped, the bigger the hole. Removing too much water in that spot is like pinching that bed sheet and pulling it down. \u201cNow both directions want to come in,\u201d he says. \u201cThe marble rolls towards the hole.\u201d Fresh water continues to flow from farther inland. At the same time, salty seawater now moves in from the coast. This can make the groundwater salty.<\/p>\n By adding purified wastewater to the aquifer, SWIFT is designed to combat both subsidence and the intruding saltwater. And it works.<\/p>\n Do you have a science question? We can help!<\/p>\n Submit your question here<\/a>, and we might answer it an upcoming issue of\u00a0Science News Explores<\/p>\n \u201cWhen we put water in the ground, the aquifer expands,\u201d Holloway says. The ground level nearby rises in small but measurable amounts. The program is still in early stages, returning 3.8 million liters (1 million gallons) to the ground each day.<\/p>\n The goal over the next five years is to increase water additions 50-fold. Eventually, SWIFT could stop land subsidence in the area and ensure a continuous source of fresh drinking water for millions of people.<\/p>\n Putting nature to work<\/p>\n In Europe, the Netherlands is known for dikes that hold back the sea. \u201cAlmost half of the Netherlands is below sea level,\u201d notes Tom Wils. He works in the country at Utrecht University. As a physical geographer, he studies landscapes. Without dikes, this nation\u2019s low-lying peatlands would be underwater.<\/p>\n These areas weren\u2019t always below sea level. Around the year 900, the peatland \u201cwas about 2 meters [6.5 feet] above sea level,\u201d Wils says. Peat forms in wet spots, where moss and other plants partially decay. A carbon-rich layer builds up over time that can be used as fertilizer or fuel. But the land was too soggy to make good farmland. So the Dutch began to drain these bogs<\/a>. That\u2019s when their land subsidence started, Wils says.\u00a0<\/p>\n Today, the Dutch use their peatlands to raise dairy cattle. But they must first drain off excess water. Otherwise, this land is too wet to support the cows. So the land continues to sink.<\/p>\n The Dutch peatlands now lie 2 meters (6.5 feet) below sea level \u2014 a drop of 4 meters (13 feet) in most areas. The drop goes even deeper in places where people have harvested peat for fuel.<\/p>\n Wils is studying new ways to reduce subsidence while supporting the land and people here.<\/p>\n One approach is called paludiculture (Puh-LOO-duh-kul-tchur). That\u2019s a fancy term for \u201ccultivating crops that grow in wet environments,\u201d Wils explains. These include cattails and reeds \u2014 two types of fibrous plants that can be used as construction materials. Cranberries and rice can be grown at such sites for food.<\/p>\n Adding water back to the land fluffs up the peat. It also allows new peat to form, which raises the height of the land.<\/p>\n Most Dutch paludiculture fields are experimental. But the country now hosts one successful cranberry farm.<\/p>\n Of course, there are challenges to this wet farming. Flooded fields can release methane<\/a> (CH4), a powerful greenhouse gas<\/a>. It\u2019s a stronger threat to climate change than is carbon dioxide (CO2). Flooded rice paddies commonly spew methane. So Wils is studying ways to cut their release of this gas. He doesn\u2019t want a fix for subsidence that worsens climate change.<\/p>\n Nature can help with subsidence, too. Because peatlands are often part of river deltas, they can be crisscrossed by many streams and rivers. When they flood, nearby reeds, trees and other plants can trap sediments to help form new peat. It takes time for this new peat to build up, Wils notes. But areas where this happens can work as a nature-based solution to help lift the land.<\/p>\n![\"a](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2025\/10\/1440_sinking_cities_sinkhole.jpg\")
This sinkhole is at Florida\u2019s Lafayette Blue Springs State Park. Some of the state\u2019s many sinkholes developed naturally, long ago. But due to groundwater extraction, large numbers of new sinkholes have been opening up throughout Florida. Many will develop into lakes as they fill with water from springs or rains.Michael Warren\/iStock Unreleased\/Getty Images Plus<\/p>\n![\"an](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2025\/10\/1440_sinking_cities_Sanya_Mangrove_Park.jpg\")
Sanya Mangrove Park in Hainan, China, collects stormwater from the surrounding city. Wetlands inside the park filter the water and allow it to soak back into the ground.Kongjian Yu\/Turenscape<\/p>\n![\"a](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2025\/10\/1440_sinking_cities_peatland.jpg\")
When left alone, peatlands like this one contain a mix of plants and water.catolla\/iStock\/Getty Images Plus<\/p>\n![\"a](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2025\/10\/1440_sinking_cities_bog.jpg\")
Cranberries grow in bogs like this one, which has been flooded in preparation for harvest.Sanghwan Kim\/iStock\/Getty Image Plus<\/p>\n