Rising sea levels pose a threat to the future of coastal cities around the world, but another major concern is the sinking of the cities themselves. "Relative local land subsidence" (RLLS), the term used to describe the phenomenon, happens when underground materials compact or collapse and cause the surface above to sink.
Using research that tracked land subsidence changes in 48 high-population coastal cities located within 50 kilometers of the coastline between 2014 and 2020, Planet Anomaly mapped the fastest-sinking coastal cities across the globe.
Key Findings:
-
Of the 44 sinking coastal cities found to be sinking faster than sea levels were rising, 30 are found in Asia.
-
Tianjin, China, and Ho Chi Minh City, Vietnam, top the list of the fasting-sinking coastal cities overall, with peak RLLS velocities of 43 mm a year in the time period examined.
-
When it comes to the 10 fast-sinking coastal cities, the only non-Asian areas are Houston, US; Lagos, Nigeria; and, technically, Istanbul, Turkey, which lies across both Asia and Europe.
-
The study's authors note that many of the sinking coastal areas identified are "rapidly expanding megacities," and count "high demands for groundwater extraction and loading from densely constructed building structures" among the factors contributing to local land subsidence.
Click image to enlarge
Via Visual Capitalist.
