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U.S. Geological Survey Circular 1312

Ground Water on Tropical Pacific Islands—Understanding a Vital Resource

By Gordon Tribble


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To a casual observer, tropical Pacific islands seem idyllic. Closer scrutiny reveals that their generally small size makes them particularly vulnerable to economic and environmental stresses imposed by rapidly growing populations, increasing economic development, and global climate change. On these islands, freshwater is one of the most precious resources. Ground water is the main source of drinking water on many islands, and for quite a few islands, it is the only reliable source of water throughout the year. Faced with a growing demand for this valuable resource, and the potential negative effects on its availability and quality from changes in global climate, increasingly sophisticated management approaches will be needed to ensure a dependable supply of freshwater for the residents of these islands.

Much scientific information has been collected by the U.S. Geological Survey (USGS) and other organizations about the ground-water resources of tropical Pacific islands. The aim of this Circular is to give members of the public, policymakers, and other stakeholders knowledge that will help ensure that this information can be used to make informed decisions about the management of these life-giving resources.

As the demand for freshwater grows, new monitoring and research efforts will be needed to (1) characterize the extent and sustainability of ground-water resources on different tropical Pacific islands, (2) better understand linkages between ground-water discharge and freshwater and nearshore ecosystems, and (3) prepare for the effects of climate change, which will likely include the loss of habitable land and reduced areas for the accumulation of ground water as a result of rising sea levels.

Version 1.0

Posted April 15, 2009
Revised April 27, 2009

For additional information contact:
Gordon Tribble

Pacific Islands Water Science Center

This report is also available in print from:

USGS Information Services, Box 25286,
Federal Center, Denver, CO 80225
telephone: 888 ASK-USGS; e-mail:

Part or all of this report is presented in Portable Document Format (PDF); at least version 7 of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge.

Suggested citation:

Tribble, Gordon, 2008, Ground water on tropical Pacific Islands--understanding a vital resource: U.S. Geological Survey Circular 1312, 35 p. [].




Importance of Ground Water

Precipitation and Ground-Water Recharge

Freshwater-Lens Systems

Porosity, Permeability, and Hydraulic Conductivity

High-Level Ground Water

Interactions Between Ground Water and Surface Water

Ground-Water Quality

Effects of Ground-Water Pumping

The Need for Ground-Water Data

Ecological Importance of Ground Water

Ground-Water Management

Examples of Ground-Water Use on Tropical Pacific Islands


Additional Information


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