Subsidence in Coastal Cities Throughout the World Observed by InSAR

• Published in: Geophysical research letters Vol. 49; no. 7
• Main Authors: Wu, Pei‐Chin, Wei, Meng (Matt), D’Hondt, Steven
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 16.04.2022
• Subjects: Cities; Flooding; Floods; Groundwater; Interferometric synthetic aperture radar; Monitoring; Radar data; SAR (radar); Satellite data; Satellites; Sea level; Sea level changes; Sea level measurements; Sea level rise; Subsidence; Synthetic aperture radar; Synthetic aperture radar interferometry; East Asia; Australia; North America; Europe; Africa
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2022GL098477

We measured subsidence rates in 99 coastal cities around the world between 2015 and 2020 using the PS Interferometric Synthetic Aperture Radar method and Sentinel‐1 data. In most cities, part of the land is subsiding faster than sea level is rising. If subsidence continues at present rates, these cities will be challenged by flooding much sooner than projected by sea level rise models. The most rapid subsidence is occurring in South, Southeast, and East Asia. However, rapid subsidence is also happening in North America, Europe, Africa, and Australia. Human activity—primarily groundwater extraction—is likely the main cause of this subsidence. Expanded monitoring and policy interventions are required to reduce subsidence rates and minimize their consequences. Plain Language Summary Satellite data indicate that land is subsiding faster than sea level is rising in many coastal cities throughout the world. If subsidence continues at recent rates, these cities will be challenged by flooding much sooner than projected by sea level rise models. We measured subsidence rates in 99 coastal cities around the world between 2015 and 2020 using satellite data. Subsidence rates are highly variable within cities and from city to city. The most rapid subsidence is occurring in South, Southeast, and East Asia. However, rapid subsidence is also happening in North America, Europe, Africa, and Australia. Human activity—primarily groundwater extraction—is likely the main cause of this subsidence. Expanded monitoring and policy interventions are required to reduce subsidence rates and minimize their consequences. Key Points We measured the subsidence rate for 99 coastal cities around the world between 2015 and 2020 using the PS Interferometric Synthetic Aperture Radar method and Sentinel‐1 data In most cities, part of the land is subsiding faster than sea level is rising and will be challenged by flooding sooner than expected Coastal nations must institute continuous monitoring and policy interventions to reduce subsidence rates and minimize their consequences