Temporal analysis of groundwater quality in a small island developing state: Mauritius Island

ABSTRACT This study explores groundwater quality dynamics in Mauritius over an 11-year period (2010–2021), emphasising the island's vulnerability to natural and human-induced pressures. Groundwater, which supplies 60% of Mauritius's water needs, is under increasing threat from climate change, overextraction, and shifting rainfall patterns. Rising temperatures and reduced precipitation are limiting aquifer recharge, especially in arid zones, leading to declining water quality. The UNFCCC highlights the risk of saltwater intrusion into coastal aquifers, a concern for Mauritius given its geographic location in the South-West Indian Ocean. The study analyses the island's water balance, where only 10% of rainfall recharges groundwater, while 60% becomes runoff and 30% is lost to evaporation and plant uptake. Using statistical analysis at a 95% confidence level, the study evaluates trends in key physical and chemical parameters (e.g., pH, TDS, chloride, nitrate, sulphate, and salinity) across five major aquifers. The findings indicate a subtle degradation in groundwater quality, particularly in pH levels, with limited correlation to rainfall variability based on the Standard Precipitation Index (SPI). The results point towards anthropogenic factors as potential contributors to this decline. This research offers essential insights for policymakers to develop sustainable, data-driven groundwater management strategies in Mauritius and similar island settings.