Thermal effects alter groundwater flow and solute transport in tidal coastal aquifers

• What happened: Researchers have found that temperature differences between groundwater and seawater significantly affect flow dynamics, salinity patterns, and nutrient transport in tidally influenced coastal aquifers.

• Why it matters now: Rising coastal water temperatures due to climate change could alter freshwater availability and saltwater intrusion in nearshore aquifers.

• Impact on people: Coastal communities relying on groundwater for drinking water, irrigation, or aquaculture could face changes in water quality and availability.

• Who is affected: Scientists, environmental planners, water resource managers, and coastal populations.

Beijing / Xiamen, January 2026: A new study examines how temperature contrasts between groundwater and seawater influence nearshore aquifers on mild-slope beaches exposed to tides. Using a physics-based multi-component numerical model, researchers simulated coupled groundwater flow with solute and heat transport, revealing complex interactions that affect saltwater intrusion and nutrient cycling.

The study found that warmer seawater reduces the period of unstable flow cycles compared to constant-temperature scenarios. As seawater temperature rises, both mixing intensity and groundwater-seawater exchange flux increase, due to temperature-driven changes in the aquifer’s hydraulic properties. Additionally, higher temperatures change the formation of salt fingers, creating more variable salinity distributions along the aquifer.

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Implications for coastal aquifers

The findings highlight that temperature cannot be ignored when evaluating nearshore groundwater systems. Coastal aquifers play a critical role in freshwater supply, nutrient transport, and ecological balance, and temperature-driven changes may:

• Accelerate saltwater intrusion into freshwater zones

• Alter nutrient cycling and contaminant transport

• Affect aquifer management and freshwater sustainability

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Toward more comprehensive modeling

The researchers stress the need for a temperature-inclusive framework to predict nearshore flow and solute transport. Such models are essential for:

• Planning sustainable water extraction

• Managing coastal environmental impacts

• Assessing climate change risks to groundwater resources

By integrating heat transport into aquifer models, scientists and policymakers can better anticipate changes in water quality and availability along tidal coastlines.