Project name: GROundwater and climate Through Time – modern Observations and Stalagmite-based recharge estimates on a raised coral atoll

15.09.2025

Sustainable groundwater management is one of the defining societal challenges under rapid global change. But in many Small Island Developing States (SIDS), effective resource management is complicated by a lack of comprehensive groundwater assessments and an inherent susceptibility to natural and anthropogenic pressures on water quantity and quality. The limited understanding of present-day groundwater dynamics in SIDS is only matched by our insufficient knowledge of past global change in oceanic regions. These combined challenges preclude confident climate predictions and mitigation measures. To address critical knowledge gaps relevant to local resource managers, and extend the sparse South Pacific palaeoclimate record beyond the instrumental period, my project GROTTOS
('GROundwater and climate Through Time – modern Observations and Stalagmite-based recharge estimates on a raised coral atoll') seeks to refine the quantitative understanding of groundwater recharge and its climate drivers on the South Pacific carbonate island of Niue (ca. 19°03′14′′S, 169°55′12′′W). Taking advantage of the tropical karst geology, GROTTOS firstly aims to provide a holistic assessment of Niue’s present-day recharge dynamics by the novel integration of conventional groundwater monitoring with observations from soil and caves in the unsaturated zone. Aligned with local priorities, groundwater will further be analysed against international quality standards and for the first time tested for major synthetic pollutants. Finally, we aim to apply a newly developed quantitative geochemical proxy for past cave drip rates to several Holocene Niuean stalagmites. With insights from modern observations, this will shed new light on South Pacific climate variability and its effect on groundwater recharge through time.