39-7 Investigating Groundwater Dynamics in Barbados using Forensic Hydrology and Dye Tracing Techniques

Session: Understanding Karst Hydrology and Karst Aquifers Using Innovative Tracers and Other Technologies

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The small karst island of Barbados, located in the North Atlantic Ocean bordering the eastern Caribbean Sea, faces water resource management challenges investigated in this study. The island's vulnerability to changing storm patterns and sea level rise is compounded by its reliance on karst aquifers for its freshwater supply, which highlights the urgency for integrated, sustainable water resource management. Through a collaboration with the Barbados Water Authority, this research aimed to provide meaningful datasets for addressing critical questions regarding groundwater-surface water interactions, recharge dynamics, and the influence of human activities on the islands’ karst hydrology. Using a multifaceted environmental tracer approach, including water level and precipitation data and fluorescent dye tracing, an investigation was undertaken in the Bowmanston’s groundwater basin, which is one of the largest on the island and also a primary source of water for its residents. Six total dye traces were conducted in January and June of 2025 involving a variety of injection features, including monitoring wells and sinkholes, with nine established dye recovery monitoring sites at springs, as well as monitoring and pumping wells throughout the Bowmanston’s and adjacent basins, wherein activated charcoal receptors were placed and exchanged every two weeks. Multiple types of injection and monitoring methods were developed to ensure consistent dye injection and receptor recovery at the sites. Water level and geochemical data from select injection and/or monitoring sites were collected hourly for the duration of the study period. Despite extremely dry conditions during the study period, initial results indicate connectivity between theorized basin boundaries, effectively expanding the potential size of the Bowmanston’s basin under the hydrologic conditions during the period of study. The relationship between conduit and matrix flowpaths suggest complexity in the recharge and transmissivity of the aquifer, with the potential for sedimentation and contaminants to move rapidly under low flow conditions. High elevation recharge sites may provide flow contribution to multiple basins, demonstrating the spatial variability of recharge effectiveness during storm events, along with hydraulic gradient attenuation due to aquifer geomorphology, and the need for additional hydrologic monitoring sites and continued dye trace investigations. 

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-11111

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