The historic city of Alexandria, Egypt, is facing an alarming increase in building collapses, with incidents rising from one per year to around 40 annually. Researchers point to sea-level rise and seawater intrusion as the primary culprits behind this disturbing trend. The true cost of this loss extends far beyond bricks and mortar.
We are witnessing the gradual disappearance of historic sites, with Alexandria sounding the alarm,” said Essam Heggy, a water scientist at the USC Viterbi School of Engineering. Alexandria, with its history spanning over two millennia, has withstood earthquakes and conquests. However, the city’s resilience is now being tested by modern challenges.
Sara Fouad, a landscape architect at TUM and the study’s first author, noted, “For centuries, Alexandria’s structures stood as marvels of resilient engineering, enduring earthquakes, storm surges, tsunamis, and more. But now, rising seas and intensifying storms – fueled by climate change – are undoing in decades what took millennia of human ingenuity to create.
Even small increments in sea level, just a few centimeters, can prove destructive for coastal cities by weakening the ground beneath buildings and eroding essential infrastructure. These dangers are not unique to Alexandria, as scientists have identified similar issues along many shorelines worldwide.
The research on Alexandria mirrors findings in parts of California, such as the San Francisco Bay Area, Central Valley, and coastal Southern California, which are also experiencing sinking. When combined with coastal erosion, these changes significantly increase flood risks.
Sea-level rise impacts historic Alexandria
Our study challenges the common misconception that we’ll only need to worry when sea levels rise by a meter,” Heggy said. “However, what we’re showing here is that coastlines globally, especially Mediterranean coastlines similar to California’s, are already changing and causing building collapses at an unprecedented rate.”
The research team employed a three-part strategy to quantify the growing crisis in Alexandria. They created a detailed digital map of collapsed buildings, examined satellite images and historical maps to chart shoreline recession, and conducted a chemical isotope analysis of soil samples to identify seawater intrusion.
“Our isotope analysis revealed that buildings are collapsing from the bottom up, as seawater intrusion erodes foundations and weakens the soil. It isn’t the buildings themselves, but the ground underneath them that’s being affected,” said Ibrahim H. Saleh, a soil radiation scientist and one of the study’s co-authors.
Among the proposed solutions is a nature-based coastal defense strategy involving the creation of sand dunes and planting vegetation along the shoreline. This approach could help slow incoming seawater and prevent groundwater levels from rising to the point where they compromise building foundations. The study’s authors emphasize the importance of preserving Alexandria’s diverse architectural attributes as a reminder of how landscape transformation has played a crucial role in creating climate-resilient societies.
They urge immediate action in Alexandria and view the city as a warning for other coastal urban centers worldwide. The study is published in Earth’s Future, an American Geophysical Union (AGU) journal.
Image Credits: Photo by L.W. on Unsplash
April Isaacs is a news contributor for DevX.com She is long-term, self-proclaimed nerd. She loves all things tech and computers and still has her first Dreamcast system. It is lovingly named Joni, after Joni Mitchell.
