US coastal land subsidence affects 84 million people, study finds
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Researchers from Tufts University and Virginia Tech analyzed over 190 million measurements and found that 43% of US coastlines are sinking at least 2 mm per year. Approximately 84.3 million people live in these subsiding coastal areas, facing increased risks to infrastructure and flood protection systems.
Key Facts
- 43% of US coastlines are sinking at least 2 mm per year, and 23.3% are sinking at least 3 mm per year.
- Approximately 84.3 million people live in US coastal areas experiencing varying levels of land subsidence.
- The most pronounced subsidence is observed around the Gulf of Mexico, with widespread sinking also along the East Coast.
- The study analyzed over 190 million measurements, mostly from satellite radar data.
Study Methodology
Researchers from Tufts University and Virginia Tech examined more than 190 million measurements to map coastal elevation changes. The data, largely derived from satellite radar, revealed both sea level rise and downward land movement.
Regional Variation
The Gulf of Mexico region shows the most significant subsidence, while the East Coast also experiences widespread sinking. On the West Coast, some areas are sinking while others are rising, indicating region-specific causes.
Causes and Impacts
Groundwater extraction, compaction of soft soils and sediments, and glacial isostatic adjustment contribute to coastal subsidence. Even small annual land subsidence accumulates over time, amplifying the effects of sea level rise on coastal flooding. Subsidence increases stress on roads, bridges, buildings, pipelines, seawalls, and flood protection systems.
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