Hydrogeological conceptualization of a small island groundwater system using historical data

Abstract

Past hydrogeological processes and human impacts may exert substantial memory effects on today’s groundwater systems. Thorough characterization of such long-term processes is required for scientists and policymakers to predict the hydrogeological impacts of land management options. Especially in data-scarce areas, historical data are essential to unravel long-term hydrogeological processes, which could not be identified by short-term fieldwork or model simulations alone. However, historical data are often overlooked or only used as background information in most hydrogeological studies. We show that the combination of historical reports and quantitative data yields major insights in the hydrogeological system of Curaçao, a small semi-arid Caribbean island. Reconstructing the island’s groundwater conditions over the past 500 years revealed that deforestation and excessive abstraction has had a detrimental effect on the island’s groundwater reserves. Historical notes and data revealed major signs of seawater intrusion, especially during abstraction peaks in the island’s industrial era. Intrusion effects are still observed locally on the island today, but additional groundwater recharge by waste water has caused freshening elsewhere. We hypothesize that the observed aquifer replenishment locally enhances submarine groundwater discharge, flushing accumulated nutrients and pollutants towards Curaçao’s fringing coral reefs. We expect that this study’s insights motivate more hydrogeologists to use historical reports and data in future studies.

Keywords

• Submarine groundwater discharge
• artificial recharge
• socio-hydrogeology
• Caribbean
• groundwater abstraction
• Historical data