Trinidad and Tobago is a developing two-island nation in the Lesser Antilles of the Caribbean. Tobago is the smaller island and has small highly heterogeneous aquifers composed of igneous and metamorphic crystalline rock with strong structural controls on the spatial distribution of permeability. Hydrogeologic analyses of the water budget and groundwater production suggest that portions of the island are underlain by prolific fractured-rock aquifer systems. This study quantifies the amount and spatial distribution of recharge, as well as the fraction of recharge captured by groundwater pumping, using historical data, new field data, remote sensing data, multiple storage quantification methods and stable isotope analysis. Despite extensive freshwater withdrawals, groundwater production reaches only ~10% of annual groundwater recharge. Groundwater capture zones are created using a first-order hydrologic balance approach and with backward particle tracking in a steady-state groundwater model. Both approaches to generating capture zones suggest that many wells capture water from outside their topographic watershed. The location of sustainable, high yield, fresh potable groundwater wells less than 1 km from the coast, that have fractured bedrock intakes well below sea level, supports the concept of a rigorous and active groundwater flow system. Understanding the hydrogeology of small bedrock island aquifers is critical to evaluating groundwater resources, especially in the Caribbean where there is strong seasonality in precipitation, finite surface-water storage and increases in potable water demand.

特立尼达和多巴哥是加勒比小安的列斯群岛一个发展中的两岛国家。多巴哥是一个较小的岛屿，拥有由火成岩和变质结晶岩组成的高度不均匀的小含水层，对渗透率的空间分布具有很强的结构控制能力。对水量和地下水产量的水文地质分析表明，该岛的部分地区被多产的裂隙岩层含水层系统所掩盖。这项研究使用历史数据，新油田数据，遥感数据，多种存储量化方法和稳定同位素分析来量化补给量和空间分布，以及由地下水泵抽出的补给量。尽管有大量淡水抽取，但地下水产量仅达到每年地下水补给量的10％。使用一阶水文平衡方法并在稳态地下水模型中使用反向粒子跟踪来创建地下水捕获区。两种生成捕获区的方法都表明，许多井都从其地形流域外部捕获水。距海岸不到1公里的可持续，高产，新鲜饮用水井的位置，使基岩取水口的裂缝远低于海平面，这支持了严格而活跃的地下水流系统的概念。了解小型基岩岛含水层的水文地质状况对于评估地下水资源至关重要，尤其是在加勒比地区，该地区降水量季节性强，地表水储量有限且饮用水需求量增加。