As coastal cities in the United States grapple with the increasing threat of flooding, an unexpected contributor to this problem has emerged: land subsidence. This phenomenon, characterized by the gradual sinking or settling of land, exacerbates flood risks and poses significant challenges for urban areas along the coast.
Rising sea levels threaten coastal communities worldwide; the United States is no exception. A new study published in Nature sheds light on a previously under-considered factor worsening flood risks in 32 major US coastal cities: land subsidence.
The study, conducted by researchers at Virginia Tech, utilized high-resolution satellite data to measure land motion (sinking or rising) alongside existing sea-level rise projections. Their findings paint a concerning picture: even with current coastal defenses, a significant increase in flooded land area is predicted by 2050.
Land Subsidence: A Hidden Threat
Traditionally, coastal and urban management plans have focused primarily on rising sea levels. However, this study highlights the critical role of land subsidence.
Land subsidence occurs when coastal land areas sink due to various factors, including natural processes like sediment compaction and human activities like groundwater extraction. The combined effect of rising sea levels and sinking land creates a scenario where coastal areas are inundated more quickly and severely.
The Scale of the Challenge
The research predicts that by 2050, an additional 1,006 to 1,389 square kilometers of land could be threatened by flooding due to this combined effect. It impacts tens of thousands to hundreds of thousands of people and tens of thousands of properties.
These findings underscore the importance of factoring land subsidence into coastal management strategies. Previous flood risk projections may have underestimated the true extent of the threat by not considering this crucial factor.
A Call to Action for Coastal Communities
The research serves as a wake-up call for coastal communities across the US. By incorporating land subsidence data into future planning, cities can develop more accurate flood risk assessments and implement effective adaptation strategies.
Rising sea levels are a reality of climate change, and addressing this multifaceted challenge is crucial to ensuring the safety and well-being of coastal populations. Taking action now can help mitigate the risks and protect these communities for generations.
Addressing the complex issue of land subsidence requires comprehensive strategies encompassing sustainable water management practices, regulations on groundwater usage, and improved urban planning guidelines that consider long-term impacts on land stability. Additionally, monitoring systems can play a crucial role in tracking changes in ground elevation over time.
In light of these challenges posed by land subsidence-induced exacerbation of floods, policymakers, state agencies, and local communities must collaborate effectively to implement proactive mitigation measures that safeguard against future flooding events while addressing underlying causes contributing to surface instability.
References: Ohenhen, L. O. et al. Nature, 2024, 627, 108–115. doi:10.1038/s41586-024-07038-3.
