Investigating the Effects of Climate Change on Freshwater Lenses

AUTHOR: Latdavone Vilaysouk
FACULTY: Dr. Megan Dixon
DEPARTMENT: Environmental Studies

ABSTRACT

On a small island where there is no reservoir for surface water, the inhabitants rely heavily on harvested rainwater and fresh groundwater drawn from freshwater lenses to support their lives. A freshwater lens is a body of freshwater that is floating above the seawater due to its smaller density than saltwater. The size of a lens is primarily defined by the elevation of the water table and the recharge rate. Because small islands are vulnerable to the changing climate, thus the water table elevations and freshwater lenses will also be significantly affected. In this study, I aim to investigate the impacts of climate change on the freshwater lens on sloping islands using closed-form analytical solutions and sensitivity analysis. The climate factors used to evaluate freshwater lenses on small islands are recharge rate and changes in sea level, which are derived from the average of data collected in other studies on the freshwater lenses on small islands. The study also compares the effects of climate change on freshwater lenses on strip islands and circular islands. The results showed that although the sea level increased due to higher carbon dioxide concentrations in the atmosphere, the volume of freshwater lenses in small islands can remain the same or even increase. The results can be explained by the slopes of the islands and the recharge rate (precipitation). Islands with larger slopes are more resilient to sea-level rise and variability in the volume of the freshwater lens, whereas islands with smaller coastal slopes are the opposite.