Alexandria, Egypt, often celebrated as the “bride of the Mediterranean” for its breathtaking beauty and storied past, is facing an unprecedented crisis. A groundbreaking study from the University of Southern California (USC) has uncovered Egypt’s vanishing coastlines driven by rising sea levels and seawater intrusion. What was once a rare event—approximately one collapse per year—has escalated to 40 incidents annually over the past decade. This frightening trend threatens the physical infrastructure of one of the world’s oldest towns and raises a broader warning about the vulnerability of coastal urban areas globally.

As climate change intensifies, the loss of Alexandria’s historic structures underscores a more profound tragedy: the erosion of cultural heritage and human ingenuity that spanned millennia. This article explores the causes behind Egypt’s vanishing coastlines, the innovative methods to track it, and potential solutions to safeguard coastal cities like Alexandria for future generations.

Egypt’s Vanishing Coastlines Caused By Coastal Erosion

For ages, Alexandria’s architecture symbolized human resilience, withstanding earthquakes, tsunamis, and storms. Today, however, the city faces a new and persistent adversary: increasing sea levels caused by climate change. According to Essam Heggy, a water scientist at USC Viterbi School of Engineering and the study’s corresponding author, even tiny rises in sea level—only a few centimetres—can cause chaos. These slight alterations allow seawater to permeate coastal soils, destabilizing the foundations of long-standing structures. The study, published in Earth’s Future, finds that Alexandria’s collapse rate has skyrocketed, a phenomenon replicated in California, where sinking ground and seawater intrusion are exacerbating flooding and infrastructure damage.

The repercussions of Egypt’s vanishing coastlines go far beyond Egypt’s borders. Sara Fouad, a landscape architect at the Technical University of Munich (TUM) and the study’s first author, emphasises that climate change is undoing centuries of engineering achievements in mere decades. The facts are clear: what was once a distant threat has become a pressing reality that requires immediate response from urban planners and governments worldwide.

The USC study challenges the long-held belief that significant sea level rise—a metre or more—is required to cause widespread damage. Instead, it demonstrates that coastlines, particularly those in the Mediterranean with parallels to California, are already changing dramatically. Alexandria’s diminishing coastline has boosted groundwater levels, allowing corrosive seawater to come into touch with building foundations. This “bottom-up” erosion, as stated by co-author Ibrahim H. Saleh, a soil radiation scientist at Alexandria University, is the underlying cause of the city’s collapsed structures. The findings serve as a wake-up call: coastal erosion is not an issue of the future; it is happening right now, and historic cities are at the forefront.

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Tracking Crisis: Innovative Methods and Sobering Insights

USC researchers used a multidimensional strategy combining cutting-edge technology with historical data to assess the depth of Alexandria’s crisis better. The initial stage was to develop a complete digital map utilizing geographic information system (GIS) technology. This map showed collapsed buildings in six districts of Alexandria’s old urban heart, one of the city’s most heavily populated neighborhoods. The map covered the years 2001 to 2021 and included information about each building’s location, size, age, construction materials, foundation depth, and number of levels. The data was methodically gathered from site visits, official reports, news archives, and private construction records, providing a comprehensive picture of complete and partial collapses.

Next, the team used satellite photos and historical maps (from 1887, 1959, and 2001) to follow the movement of Alexandria’s 50-mile coastline. Their findings revealed that areas of the shoreline have retreated tens of meters inland over the last two decades, a gradual but continuous encroachment that has profoundly transformed the city’s landscape. By estimating the rate of retreat over the last century, the researchers showed that the retreating shoreline raises groundwater levels, filling the earth beneath coastal buildings with seawater. This saturation weakened the ground, paving the way for structural failure.

The final piece of the jigsaw came from the chemical examination of soil samples. The team measured the mechanical stability of the soil using isotope “fingerprints,” such as the B7 isotope. High B7 levels suggest firm, erosion-resistant soil, whereas low levels indicate degradation. The findings were startling: seawater infiltration is degrading foundations from below, undermining soil integrity and causing buildings to collapse.

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A Way Forward: Nature-Based Solutions for Resilience

The USC study does more than simply diagnose the problem; it also provides a realistic, long-term solution. To combat coastal erosion and seawater intrusion, the researchers propose nature-based solutions such as building dunes and vegetation barriers along Alexandria’s shoreline. These natural defenses would keep the advancing ocean from boosting groundwater levels and destroying foundations. Steffen Nijhuis, a landscape-based urbanist and research co-author at Delft University of Technology, says that this strategy is both cost-effective and versatile, making it suitable for highly populated coastal regions around the world.

These interventions have the potential to improve urban life in addition to providing physical protection. The report proposes that Alexandria develop green belts and canals to help control climate extremes while reconnecting citizens with well-maintained public areas. Udo Weilacher, a co-author and landscape architect at TUM, believes that conserving the architectural diversity of Mediterranean towns such as Alexandria is more than just a matter of aesthetics; it demonstrates how landscape design can encourage climate-resilient communities.

Conclusion: A Race Against Time

Alexandria’s suffering represents a microcosm of a worldwide crisis. The USC study reveals the catastrophic interplay of rising oceans, coastal erosion, and seawater intrusion, demonstrating how these factors are destroying a metropolis once deemed invincible. From one collapse each year to 40, the figures paint a picture of escalating loss that reverberates across coastal regions from California to the Mediterranean. However, among the severe warnings is a call to action. The researchers provide a resilience roadmap by charting the harm, understanding its sources, and offering natural defenses. The question now is whether the world will listen to Alexandria’s warning before the bride of the Mediterranean—and countless historic cities like her—disappear beneath the waves. Time is like the tide which is running out.

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