Earth System Model Simulates a Raised Coastal Groundwater Table Caused by Sea-Level Rise
Scientists at Pacific Northwest National Laboratory developed a land–ocean coupling scheme within an Earth system model to assess the vulnerability of coastal groundwater to sea-level rise.
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Coastal regions face increasing threats from sea-level rise, which current Earth system models (ESMs) often overlook. This study develops a land-ocean coupling scheme within the state-of-the-science Energy Exascale Earth System Model (E3SM), revealing that seawater infiltration, driven by sea-level rise, will raise groundwater levels and increase flooding risks in low-lying coastal areas by mid-century. While sea-level rise triggers these changes, topography and rising temperatures have an even greater influence on groundwater dynamics. This work highlights the need for improved coastal modeling in Earth system simulations to better predict future flooding, water, and energy cycle shifts, and soil salinization risks.
This study fills a critical gap in ESMs by introducing the first land-ocean coupling scheme that captures seawater infiltration and groundwater exchanges due to sea-level rise. The findings are key for improving coastal flooding predictions and long-term soil salinization in vulnerable areas. The study’s innovation lies in integrating these hydrologic processes within a fully coupled ESM, enabling more accurate projections of sea-level rise impacts. This work sets the stage for future studies to incorporate factors like salinity and refined coastal inundation schemes, enhancing the ability to predict and manage climate-driven coastal hazards.
As ocean levels rise, seawater threatens to intrude into coastal freshwater aquifers that millions of people depend on for drinking water and irrigation. While regional studies have examined the impacts of sea-level rise on coastal groundwater systems, current ESMs overlook the exchange of water between the ocean and groundwater. A team of researchers from Pacific Northwest National Laboratory addresses this gap by developing a water exchange process between the ocean and land components in E3SM. This coupling scheme includes lateral exchanges between seawater and groundwater, as well as vertical seawater infiltration resulting from oceanic inundation. The team used this new coupled model to assess sea-level rise impacts on the global coastal groundwater table under a higher CO2 emission scenario. Results from the coupled model indicate that sea-level rise will raise groundwater levels and intensify the hydrological cycle by midcentury mainly because of increased seawater infiltration. Further, while sea-level rise triggers this increased seawater infiltration, the topography and warming temperature play more significant roles in determining its magnitude.