Over the past 40 years, investigations in Tongatapu have identified a number of natural and
human-related factors that increase or have the potential to increase the vulnerability of fresh
groundwater sources. Some of these studies have suggested strategies to lessen impacts and
improve resilience. This project builds on the considerable weight of those results as well as the
depth of local expertise and the valuable, long-term record of monitoring. Our aim here is to
Water Resources Report 1992, Appendices A-H
Water Resources Report 1992, Appendices I-K
Water Resources Report 1992 : Appendices L-O
Map showing reefs with in the different Impact Zones.
The study was a remarkably productive and enriching experience for all who were involved. It became a forum for critical reflections and analysis. It also built a knowledge and understanding amongst different communities, villages and the survey team.
Water Resources Report 1992, Fig 4.1-5.17
Water Resources Report 1992, Figs 5.17-5.53
Access to safe drinking water is a basic need and is one of the most important contributors to public health and to the economic health of communities. Pacific island countries have yet to overcome the challenge of providing a safe and adequate supply of drinking water to its populations. Infectious, waterborne diseases, such as Typhoid and Cholera and newly emerging pathogens are a major cause of morbidity and mortality within the Pacific region.
An analysis is made of the groundwater resources of Tongatapu Island. The Ghyben-Herzberg approximation is used to estimate thicknesses of a fresh-water lens floating on seawater. Finite-difference calculations are used to estimate rainfall recharge rates, and calculations are made to investigate the dispersion of chloride ions across the fresh-water-sale-water interface. These calculations suggest that artificial recharge might be useful devise to control chloride concentrations in the fresh-water aquifier.