Land under the country’s largest cities is sinking. Here’s where — and why

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🗞️ Driving the news: New research published in Nature Cities finds that the land beneath America's largest cities is slowly sinking, or subsiding, posing significant risks to infrastructure
• Across the 28 most populous U.S. cities, subsidence affects two-thirds of urban land, impacting around 34 million people
• Cities such as Chicago, Dallas, New York, and Houston are among the most severely affected, with over 98% of their areas showing land compression

🔭 The context: Subsidence has traditionally been a concern for coastal cities vulnerable to sea-level rise
• However, this study highlights that inland cities are equally at risk, driven by diverse factors: groundwater extraction, glacial isostatic adjustment from past ice ages, building weight, underground heat absorption, and tectonic activity
• In cities like Washington, D.C., localized variations such as reclaimed land have exacerbated sinking

🌍 Why it matters for the planet: As urban centers sink, they face heightened flood risks, destabilized infrastructure, and long-term sustainability challenges
• Groundwater extraction, the primary driver (accounting for 80% of observed sinkage), underscores the need for resilient water management
• Without mitigation, subsidence could severely compromise climate adaptation efforts, particularly by altering stormwater drainage and damaging critical buildings

⏭️ What's next: Cities must prioritize detailed subsidence mapping and groundwater management strategies
• Solutions such as aquifer recharge using rainwater, river water, or treated wastewater — as implemented in parts of California, Spain, and China — could mitigate further sinking
• Researchers urge immediate urban planning reforms and infrastructure assessments to preempt compounding risks in future decades

💬 One quote: "The good thing about land subsidence is that rates are very slow and give time for communities to prepare or mitigate the effects." — Manoochehr Shirzaei, Virginia Tech researcher and study co-author

📈 One stat: 29,000 buildings across the 28 studied cities are located on precarious, destabilized ground, with San Antonio showing the highest risk — 1 in every 45 buildings

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