Groundwater Resource Vulnerability for Small Island Developing States

Abstract:

Groundwater constitutes the majority of naturally-occurring freshwater supply on many small islands. However, in addition to potential impacts of climate change and population growth that may compromise water supply and demand on small islands, Small Island Developing States (SIDS) often lack hydrogeological data for characterizing aquifers and have limited institutional means for managing the groundwater resource. As part of UNESCO-IHP’s Transboundary Water Assessment Programme (TWAP), an assessment of groundwater systems on 43 SIDS was undertaken. This SIDS assessment represents the first baseline global assessment of the status of groundwater in SIDS, covering all major island states of the world with an area less than 50,000 km². As many SIDS comprise multiple islands with different hydrogeologic settings, a representative island from each SIDS was chosen to represent the majority of the population. Data were compiled from publications, accessible datasets and a questionnaire distributed to collect local expertise. A total of 74 variables were defined for each SIDS, according to the level of confidence in the data (i.e. high confidence when based on specific studies and low confidence when inferred). These variables represent the current hydrogeologic conditions for each island and were used to define indicators that characterise vulnerability. Recharge was modelled for both current and future projected climate change for the 2060s using regionally downscaled data for each SIDS to identify islands likely to experience significant stress due to changes in recharge. The assessment results were categorized based on island type to identify trends in hydrogeologic conditions and vulnerability for similar island types. Despite limitations and uncertainty in the data used in the assessment, the results provide a broad assessment of current and future groundwater resource vulnerability for SIDS throughout the world.