Quantification of submarine groundwater discharge towards coral reefs around Curaçao, a semi-arid island in the Caribbean.

Recent studies show that submarine groundwater discharge (SGD) often equals or exceeds riverine inputs into marine environments. Pollution or extraction of groundwater may affect submarine groundwater discharge quality and quantity, impacting marine ecosystems. Most research focuses on relatively humid environments where large amounts of SGD can be expected and detected.

However, SGD has been poorly studied on smaller (semi-)arid islands, where SGD is relatively hard to detect and quantify. We aim to shine a light on the hydrogeological link between terrestrial processes and coral reef health in the semi-arid Caribbean island Curaçao.

It is hypothesized that the coral reef around the island is impacted by pollutants from tourism and agriculture. Previous hydrogeological measurements suggest the presence of groundwater fluxes towards the ocean through the karstic geology. However, quantitative data are lacking.

Groundwater level and quality measurements were conducted at study locations in the various geological settings of the island. Soil infiltration measurements were performed to assess the infiltration capacity of different soil types across the island. Rainfall and groundwater level fluctuations were monitored and used to determine the hydrogeological response after rainfall events. Geophysical ERT surveys have been conducted on different geomorphological settings to assess the hydrogeology and detect preferential flow paths in the karstic geology.

The field measurements will serve as input for a coupled groundwater-surface hydrology model of Curaçao in MODFLOW. The model outcomes will be used to guide field measurements in the future. These will include tracer tests, surface runoff measurements, marine Radon measurements and offshore geophysics.

This study is part of the interdisciplinary SEALINK research project, comprising nine PhD projects at different Dutch universities and research institutes.