Freshwater supplies threatened in central Pacific

An international team from The Australian National University, Ecowise Environmental, the Government of the Republic of Kiribati, the French agency CIRAD and the Pacific Islands Applied Geoscience Commission has been studying the impacts of natural and human-induced changes on groundwater in the central Pacific nation of Kiribati since 1996.

The work was initiated by UNESCO International Hydrological Programme and supported by the Australian Centre for International Agricultural Research, the Government of France, the Australian Academy of Science, the Australian Research Council and the European Union Pacific Water Governance Programme. Their work is published in a special issue of the Aug. 2007 Vadose Zone Journal which followed an International Symposium on Groundwater Resources Assessment under the Pressures of Humanity and Climate Change held in Kyoto in April 2006 and coordinated by the Japanese Research Institute for Humanity and Nature.

Very limited land areas and extremely permeable coral soils in atolls reduce surface runoff to insignificant amounts and decrease the potential for surface storages of water. This means thin lenses of fresh groundwater floating over seawater are the major source of reliable freshwater for people in many atolls. The team found that both the quantity and salinity of atoll groundwater is extremely vulnerable to frequent ENSO-related droughts. Droughts can last as long as 4 years and occur with a frequency of one significant drought, coupled to La Niña events, every 6-7 years. In long droughts domestic water wells are often too salty too drink and some communities have to rely on large groundwater lenses or on coconuts.

Population growth due to natural increases, inward migration and urbanization mean that fresh groundwater sources are reaching their limit of sustainable supply in urban South Tarawa in Kiribati. Groundwater can become salty due to over-pumping or inappropriate methods of pumping. Long, horizontal infiltration pumping galleries or “skimming wells”, placed just beneath the groundwater table (the top layer of soil and rock that is saturated with water) provide the best method of skimming off lower salinity groundwater. The study team tested the impact of infiltration galleries on lowering the watertable and on salinity. The researchers also used the results to examine how the permeability of the coral sands varied across islands and found that surface contaminants could reach shallow fresh groundwater within an hour of being split on the soil surface.

The team proposed a number of strategies to help increase the resilience of small island communities to water–related climate and human changes. These included: providing a sound institutional basis for the management of water and sanitation; improving community participation in water and related land planning and management; increasing the capacity of villagers and local agencies to manage water and sanitation under variable climates; improving knowledge of available water resources and demand for them; improving water conservation and demand management and reducing leakages; increasing the use of rainwater by households and communities; protecting groundwater source areas from contamination; improving sanitation systems to minimize water use and groundwater pollution; and ensuring that water aid programs are long-term partnerships that foster local engagement and ownership of solutions.

Source: Soil Science Society of America

Related stories:

Desalination can boost US water supplies, but environmental research needed
Recent advances in technology have made removing salt from seawater and groundwater a realistic option for increasing water supplies in some parts of the U.S., and desalination will likely have a niche in meeting the nation's future water needs, says a new report from the National Research Council. However, a coordinated research effort with steady funding is required to better understand and minimize desalination's environmental impacts -- and find ways to further lower its costs and energy use.
Researcher working on corn varieties that need less nitrogen
Jonathan Lynch has made a name for himself doing ground-breaking (pun intended) research on the roots of bean and soybean plants in an effort to improve crop yields in places such as Africa, Asia and Latin America.
Credit-card-sized platform for volatile compound analysis CAREER project goal
Developing a credit-card-sized gas chromatography platform that can analyze volatile compounds within seconds is the next step for Virginia Tech College of Engineering researcher Masoud Agah, who has received a National Science Foundation (NSF) Faculty Early Career Development Program (CAREER) Award to support his research.
Critical problems for fresh water supplies in Pacific
Despite high average annual rainfalls and balmy temperatures, an expert from The Australian National University warns that small island nations in the Pacific face freshwater supply and sanitation problems among the most critical in the world.
Space Data Unveils Evidence of Ancient Mega-lake in Northern Darfur
Researchers at the Boston University Center for Remote Sensing used recently acquired topographic data from satellites to reveal a now dry, ancient mega-lake in the Darfur province of northwestern Sudan. Drs. Eman Ghoneim and Farouk El-Baz made the finding while investigating Landsat images and Radarsat data. Radar waves are able to penetrate the fine-grained sand cover in the hot and dry eastern Sahara to reveal buried features.
Drop in acid rain altering Appalachian stream water
Appalachian hardwood forests may be getting a respite from acid rain but data from a long-term ecological study of stream chemistry suggests that the drop in acid rain may be changing biological activity in the ecosystem and hiking dissolved carbon dioxide in forest streams.
Bottled water debate hits a boiling point
A debate over water is boiling over in the United States and elsewhere amid growing environmental concerns about bottled water and questions about safety of tap water.
Mars air once had moisture
A new analysis of Martian soil data led by University of California, Berkeley, geoscientists suggests that there was once enough water in the planet's atmosphere for a light drizzle or dew to hit the ground, leaving tell-tale signs of its interaction with the planet's surface.

News discussion:

Space & Earth science news