Analytical methodology for determining the extent of pumped freshwater lenses in recharge-limited, circular islands

• Published in: Advances in water resources 2024-05, Vol.187, p.104692, Article 104692
• Main Authors: Kurylyk, Barret L., Lin, Yin-Fang, Solórzano-Rivas, S. Cristina, Werner, Adrian D.
• Format: Article
• Language: English
• Subjects: Coastal groundwater; Freshwater lens geometry; Island hydrogeology; Saltwater intrusion; Saltwater-freshwater interface
• ISSN: 0309-1708; 1872-9657
• DOI: 10.1016/j.advwatres.2024.104692

•A solution is derived for freshwater lenses with pumping and variable recharge.•The equation is verified with numerical methods and demonstrated through examples.•The approach is used to develop new vulnerability indices. Island freshwater lenses are often subjected to pumping to support the freshwater needs of isolated communities. Investigations of the lens extent commonly involve the application of analytical solutions, although the effects of pumping from circular island aquifers have not been assessed in previous analytical methodologies. In this study, a new analytical solution is derived based on Green's functions that accommodate freshwater inputs (recharge) and outputs (multiple wells) when obtaining the head distribution and sharp-interface lens shape. The solution is verified using a finite-element model for an illustrative pumping scenario. The solution is also differentiated with respect to pumping rates, recharge, and island radius to obtain vulnerability indices to characterize the lens sensitivity to changes in stresses. Finally, the analytical methodology is modified to examine the effects of non-uniform recharge. Python code incorporating the new solution is included to enable users to investigate a range of recharge and pumping scenarios.