The Egyptian port city of Alexandria is crumbling, with buildings collapsing due to rising sea levels, a study has found. The historic city, known for being the birthplace of Cleopatra and housing the ancient Library of Alexandria, has witnessed 280 buildings collapsing in the past 20 years, owing to coastal erosion.
More than 7,000 buildings are currently at risk of collapsing, according to the study published in the journal Earth's Future. Between 2014 and 2020 alone, 86 buildings completely crumbled, and 201 partially collapsed across the 2,300-year-old city, resulting in 85 deaths.
"Collapses correlate with areas undergoing chronic and severe shoreline erosion and sea level rise, accelerating seawater intrusion in coastal aquifers," the study highlighted.
For the study, scientists collected data through site visits, government reports, news archives and statements from private construction companies. Afterwards, they combined satellite imagery with historical maps from 1887, 1959 and 2001 to track shoreline movement.
Additionally, the researchers analysed isotopes in soil samples to examine the effects of seawater intrusion. They measured isotopes like B7, whose higher levels indicate stronger, more stable soil, while lower levels suggest erosion.
The crumbling is caused by seawater intruding into the groundwater under the city. As the saltwater moves inland due to rising sea levels, it increases groundwater levels beneath buildings and erodes the soil.
"The true cost of this loss extends far beyond bricks and mortar. We are witnessing the gradual disappearance of historic coastal cities, with Alexandria sounding the alarm. What once seemed like distant climate risks are now a present reality," study co-author Essam Heggy, a water scientist at the University of Southern California's Viterbi School of Engineering.
The scientists have proposed a nature-based solution to combat coastal erosion and seawater intrusion. They suggest creating sand dunes and vegetation barriers along the coastline to block encroaching seawater and prevent seawater intrusion. This way, the groundwater levels will not be pushed into building foundations.
