Estimating Freshwater Lens Volume Based on Island Circularity

Area of Science:

• Hydrogeology
• Island Hydrology
• Water Resource Management

Background:

• Freshwater lenses (FWLs) are vital drinking water sources for global islands.
• Accurate estimation of subsurface potable water is essential for island sustainability.

Purpose of the Study:

• To develop a novel method for estimating island freshwater lens volumes using island shape.
• To establish a relationship between island morphology and freshwater lens volume.

Main Methods:

• Modeling freshwater lenses using numerical steady-state approaches and the Ghyben-Herzberg relation.
• Utilizing a circularity parameter to analyze various island shapes, both real and idealized.
• Comparing modeled FWL volumes across different island geometries.

Main Results:

• Defined approximate lower and upper boundaries for FWL volume based on circularity and idealized island shapes (elliptical and circular).
• Demonstrated that island shape significantly influences FWL volume estimation.
• Found that determining maximum FWL depth intervals was not feasible with the current island subset.

Conclusions:

• The developed method offers a way to estimate FWL volumes on data-scarce islands.
• This approach can aid in assessing potential impacts of climate change on island water resources.
• Island shape is a key factor in understanding freshwater lens dynamics and availability.