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Visualized: Which Coastal Cities are Sinking the Fastest?

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See this visualization first on the Voronoi app.

A map and ranking of the fastest sinking coastal cities in the world by local land subsidence.

Which Coastal Cities Are Sinking the Fastest?

This was originally posted on our Voronoi app. Download the app for free on iOS or Android and discover incredible data-driven charts from a variety of trusted sources.

With sea levels rising, there is cause for concern about the livability of major coastal cities—often huge centers of trade and commerce, and homes to millions of people.

But an overlooked area is how coastal cities are themselves sinking—a phenomenon called relative local land subsidence (RLLS)—which occurs when underground materials, such as soil, rock, or even man-made structures, compact or collapse, causing the surface above to sink.

This can exacerbate the effects of rising sea levels (currently averaged at 3.7 mm/year), and is a useful metric to track for coastal communities.

Creator Planet Anomaly, looks at the top 10 cities ranked by the peak subsidence velocity. This graphic is based on a paper published by Nature Sustainability, which used satellite data to track land subsidence changes in 48 high-population coastal cities located within 50 kilometers of the coastline. Their data collection spanned six years from 2014 to 2020.

ℹ️ Interferometric synthetic aperture radar (InSAR) utilizes two images taken at different times, which are then compared to create an interferogram. This interferogram illustrates changes in land motion relative to a reference point in the satellite’s line-of-sight over time. By analyzing a series of these interferograms, researchers can estimate the long-term velocity of the ground’s surface for each city.

In that time period, they found that 44 of the cities they studied—many of them massively populated, developed megacities, built on flat, low-lying river deltas—had areas sinking faster than sea levels were rising.

The 10 Fastest Sinking Coastal Cities

One of the top cities on the list is Tianjin, China with a population of more than 14 million people, which has areas of the city experiencing peak RLLS velocities of 43 mm a year between 2014–2020. The median velocity is much lower, at 6 mm/year, which means some areas are sinking much faster than the overall metropolitan area.

Tianjin is bordered by Beijing municipality to the northwest and the Bohai Gulf to the east. In June 2023, large cracks appeared on Tianjin’s streets, caused by underground land collapses, a byproduct of extensive geothermal drilling, according to the local government.

RankCityCountryPeak Velocity
(mm/year)
Median Velocity
(mm/year)
1Tianjin🇨🇳 China436
2Ho Chi Minh City🇻🇳 Vietnam4316
3Chittagong🇧🇩 Bangladesh3712
4Yangon🇲🇲 Myanmar314
5Jakarta🇮🇩 Indonesia265
6Ahmedabad🇮🇳 India235
7Istanbul🇹🇷 Turkey196
8Houston🇺🇸 U.S.173
9Lagos🇳🇬 Nigeria172
10Manila🇵🇭 Philippines172

Ho Chi Minh City (population 9 million) in Vietnam also faces similar RLLS rates as Tianjin though its median velocity is much higher at 16 mm/year.

Chittagong, Bangladesh, Yangon, Myanmar, and Jakarta, Indonesia, round out the top five fastest sinking coastal cities by relative land subsidence. They all face a similar web of contributing factors as the authors of the paper note below:

“Many of these fast-subsiding coastal cities are rapidly expanding megacities, where anthropogenic factors, such as high demands for groundwater extraction and loading from densely constructed building structures, contribute to local land subsidence.” — Tay, C., Lindsey, E.O., Chin, S.T. et al.

In fact, Indonesia has ambitious plans to relocate its sinking capital, Jakarta, to another island, a move that could cost the Indonesian government more than $120 billion. This comes after the forecast that one-third of Jakarta could be submerged as early as 2050. Aside from the regular flooding, Jakarta is also extremely prone to earthquakes.

Why Measure Local Land Subsidence?

The researchers of this report argue that local land subsidence is largely underestimated in relative sea level rise assessments and is crucial for the sustainable development of coastal areas.

The data they’ve collected—peak velocity versus median velocity—also allows them to identify specific areas and neighborhoods in cities that are undergoing rapid subsidence and thus facing a greater exposure to coastal hazards.

In New York, for example, their results suggested that subsidence is only localized west of Breezy Point and “should not be extrapolated eastward along the coast” of Long Island.

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This article was published as a part of Visual Capitalist's Creator Program, which features data-driven visuals from some of our favorite Creators around the world.

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Maps

Mapped: High School Graduation Rates by State

West Virginia has the highest graduation rate, with 91% of its students graduating.

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This map shows the percentage of public school students who graduate with a regular diploma in each U.S. state.

Mapped: High School Graduation Rates by State

This was originally posted on our Voronoi app. Download the app for free on iOS or Android and discover incredible data-driven charts from a variety of trusted sources.

A high school diploma not only represents the development of essential knowledge and skills but is also a critical step toward personal and professional growth.

This graphic shows the percentage of public school students who graduate with a regular high school diploma in each U.S. state. Data is sourced from the U.S. Department of Education, National Center for Education Statistics, for the school year 2021–22.

West Virginia Has the Highest Graduation Rate

The U.S. average high school graduation rate was 87% in the school year 2021–22.

West Virginia has the highest graduation rate, with 91% of its students graduating. Meanwhile, the District of Columbia has the lowest graduation rate, with 76%.

StatePercentage
West Virginia91
Tennessee90
Wisconsin90
Kentucky90
Massachusetts90
Iowa90
Missouri90
Texas90
Virginia89
Kansas89
Connecticut89
Mississippi89
New Hampshire88
Delaware88
Utah88
Alabama88
Arkansas88
Indiana88
Florida87
Illinois87
Pennsylvania87
Nebraska87
California87
New York87
North Carolina86
Maryland86
Ohio86
Maine86
Hawaii86
Montana86
New Jersey85
North Dakota85
Georgia84
South Carolina84
Minnesota84
Washington84
Rhode Island83
Louisiana83
Vermont83
Colorado82
Wyoming82
Nevada82
Oregon81
Michigan81
Idaho80
Alaska78
Arizona77
District of Columbia76
New MexicoNot available
OklahomaNot available

Given that West Virginia typically struggles in rankings like this, this top placement might be surprising to some. This high graduation rate is part of a concerted effort by the state to increase its graduation rate.

In 2011, West Virginia’s graduation rate sat at 72% (which would put them dead last by today’s standards). How did the state see such a significant improvement? A data-driven early warning system was put in place to target individuals when they are at most risk of dropping out and using interventions to keep them on pace to graduate.

Alabama, also an early adopter of this system, saw a steep improvement in their graduation rate over the past decade and a half.

If you enjoy posts like these, check out Mapped: Personal Finance Requirements by State, which visualizes where high school students are required to take a personal finance course.

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