9 Great Cities That Are Slowly Sinking

No city is more famous for the water creeping up its walls. Venice was built on wooden pilings driven into a muddy lagoon, and over the twentieth century it sank measurably as those sediments compacted — helped along, for decades, by industry pumping groundwater from beneath it.

The pumping was stopped, which slowed the worst of it, but the sea is still rising to meet the city. The seasonal high tides Venetians call acqua alta now flood St. Mark’s Square routinely, which is why the city built the MOSE flood barriers to hold the Adriatic back on the highest days.

Jakarta may be the most dramatic case on Earth. Parts of the Indonesian capital have dropped by more than two meters over recent decades, and stretches of the north of the city now sit below sea level, held back by walls.

The cause is mostly straightforward: with unreliable piped water, millions of residents and businesses have pumped groundwater from the aquifer, and the emptied ground collapses in on itself. The problem is severe enough that Indonesia has begun moving its capital to a new city, Nusantara, on the island of Borneo.

Much of New Orleans already sits below sea level, wedged between the Mississippi River and Lake Pontchartrain. It got that way in part by design: to make the swampy delta livable, engineers drained the marshes, and the dried-out soils compacted and sank.

The levees that keep the water out also keep the river’s replenishing sediment from spreading over the land, so the ground keeps settling. Hurricane Katrina in 2005 showed, tragically, what happens when the defenses around a sinking bowl fail.

Mexico City has a peculiar problem: it was built on top of a drained lake. The Aztecs founded Tenochtitlan on an island in Lake Texcoco, and the Spanish and their successors gradually drained the basin to make dry land.

The city now sits on that old lakebed — soft clay that shrinks as the metropolis pumps out the groundwater beneath it. Some districts have sunk many meters over the past century, cracking buildings and buckling streets at wildly uneven rates across the city.

Thailand’s capital spreads across a flat river delta only a meter or two above the sea, and for years it sank steadily as factories and homes drew heavily on groundwater.

Regulations curbing that pumping have slowed the descent, but the city still sits low and wet, squeezed between subsidence from below and a rising Gulf of Thailand. Serious flooding, like the disastrous 2011 floods, remains a recurring threat.

The Dutch didn’t so much fight the low ground as move in and organize it. Rotterdam, like much of the western Netherlands, sits below sea level, on soft peat and clay reclaimed over centuries and drained by an endless network of dikes, canals, and pumps.

The peaty soils keep compacting and slowly sinking, so the pumps never stop. What’s remarkable is how well it works: the Netherlands has turned living below the waterline into ordinary engineering, and cities like Rotterdam and Amsterdam are studied worldwide as models for how to do it.

Miami’s problem is a little different — the land here isn’t dropping much, but the sea is climbing to meet it, and the city sits barely above the waterline to begin with.

What makes it tricky is the ground itself: South Florida rests on porous limestone, so seawater can seep up from below rather than only over a seawall. On sunny days with especially high tides, water now bubbles up through drains in some neighborhoods — so-called “sunny day flooding.”

Tokyo belongs on this list mostly as a success story. Through the mid-twentieth century, parts of the low-lying east of the city sank dramatically — by several meters — as heavy industry pumped out groundwater during Japan’s rapid growth.

Then Japan clamped down, restricting groundwater extraction in the 1960s and 70s, and the sinking largely stopped. It’s the clearest proof that this kind of subsidence, caught in time, can be reined in — though the ground that already dropped stayed down, protected now by floodgates and levees.

Bangladesh’s capital sits on the world’s largest river delta, a vast low plain built from silt where several great rivers meet the sea — about as flat and water-prone a place as a city can be.

As Dhaka has swollen into a megacity, heavy groundwater pumping has helped pull the ground downward, even as the delta’s soft sediments naturally settle. Combined with a rising Bay of Bengal, it leaves one of the world’s most crowded cities squeezed from both directions.