Hydrological Training 2nd Course on Surface & Groundwater, 12th – 30th June 2006.
The 3rd Hydrological Training course for Pacific Island countries was the final in a series of three courses held across a period of ten weeks, over a span of three years, from 2004 to 2006. Hydrological personnel from 13 Pacific island countries, including the Maldives, attended the training held in Suva, Fiji. The training components were divided into Surface Water Hydrology and Groundwater Hydrogeology. This year the training made provisions for 2 trainees per country to participate in each of the training components. The training occurred from the 12th to the 30th of June at both the SOPAC and Mineral Resources Department of Fiji Training/Conference Rooms. The 3rd course marks the completion of the Hydrological Training Programme which has been set up as a precursor to the Pacific Hydrology Cycle Observing System (HYCOS) project, which focuses on several core activities including flood forecasting, water resources assessment in major rivers, water resources databases, drought forecasting, groundwater and water quality monitoring and assessment.

• Promotion of Rainwater Harvesting in Pacific Island Countries

• UNESCOs International Hydrological Programme and Pacific IHP Focal Points

• Groundwater Module USP Applied Geology SC 301

• Pacific Resource Centre on Water and Climate

http://www.sopac.org/Pacific+Resource+Centre+on+Water+and+Climate

• The Island Climate Update

The ICU is a multi-disciplinary, multinational scientific project providing Pacific Islands with three-month regional climate forecasts, every month. Important contributions to the ICU are made by the meteorological services of American Samoa, Australia, Cook Islands, Fiji, French Polynesia, Kiribati, Nauru, New Caledonia, New Zealand, Niue, Papua New Guinea, Samoa, Solomon Islands, Tokelau, Tonga, Tuvalu, United States, Vanuatu and Wallis & Futuna. The ICU focuses on the provision of the probability of occurrence of climate extremes (such as tropical cyclones, floods and droughts) likely to affect each island in the coming months and latest scientific findings on key climate features (e.g. El Niño, South Pacific Convergence Zone, Interdecadal Pacific Oscillation, etc.) driving the weather and climate of each island.

Overview Paper on Water Resources Management

An Overview Paper on Water Resources Management (T.Falkland,2002) was produced as part of the 3rd World Water Forum consultations which contains more background information on water resources in the Pacific.

An extract on the 1st chapter is Provided below:

Surface water

Where conditions are favourable, surface water can occur on small high islands in the form of ephemeral and perennial streams and springs, and as freshwater lagoons, lakes and swamps.

Perennial streams and springs occur mainly in high volcanic islands where the permeability of the rock is low. Many streams are in small, steep catchments and are not perennial (e.g. Rarotonga, Cook Islands). Some streams flow for several hours or days after heavy rainfall, while others flow for longer periods but become dry in droughts.

Brackish surface water, Tarawa, Kiribati

Freshwater lagoons and small lakes are not common but are found on some small islands. These can occur in the craters of extinct volcanoes or depressions in the topography. Low-lying coral islands rarely have fresh surface water resources except where rainfall is abundant. Many small island lakes, lagoons and swamps, particularly those at or close to sea level, are brackish.

Groundwater

Groundwater occurs on small islands as either perched (high-level) or basal (low-level) aquifers.

Perched aquifers commonly occur over horizontal or sub-horizontal confining layers (aquicludes). Dyke-confined aquifers are a less common form of perched aquifer, which are formed when less permeable vertical volcanic dykes trap water in the intervening compartments (e.g. on some of the islands of Hawaii and French Polynesia).

Basal aquifers consist of unconfined, partially confined or confined freshwater bodies, which form at or below sea level. On many small coral and limestone islands, the basal aquifer takes the form of a 'freshwater lens' (or 'groundwater lens'), which underlies part of the island.

Basal aquifers tend to be more important than perched aquifers because they are more common and generally have larger storage volumes. Basal aquifers are, however, vulnerable to saline intrusion owing to the freshwater-seawater interaction, and must be carefully managed to avoid over-exploitation and consequent seawater intrusion.

Cross section through a small coral island showing main features of a freshwater lens (exaggerated vertical scale) and location of an infiltration gallery.

The term 'freshwater lens' can be misleading as it implies a distinct freshwater aquifer. In reality, there is no distinct boundary between freshwater and seawater but rather a transition zone (refer Figure 4). The base of the freshwater zone can be defined on the basis of a salinity criterion such as chloride ion concentration or electrical conductivity.

Freshwater lenses often have asymmetric shapes with the deepest portions displaced towards the lagoon side of the island, as shown in the Figure above. Typically, the freshwater zone of a thick freshwater lens on a small coral island is about 10-20 m thick, with a transition zone of a similar thickness (e.g. Tarawa, Majuro). Where the freshwater zone is less than about 5 m thick, the transition zone is often thicker than the freshwater zone. The freshwater and transition zone thicknesses are not static but vary according to fluctuations in recharge and the sustainability of the groundwater abstraction.

Rainwater

Rainwater collection systems are common on many islands. In small islands with high rainfall (e.g. the islands of Tuvalu), rainwater catchments using the roofs of individual houses and some community buildings, are the primary source of freshwater.

In other small islands, rainwater is used as a source for essential water needs (e.g. drinking and cooking). In drought periods, when rainfall can be very little, or nil for many months, household rainwater storages are susceptible to being severely depleted unless very strict rationing is imposed. Common materials for rainwater tanks are ferrocement, fibreglass and plastic. Steel tanks are generally not used, owing to corrosion problems, unless they are well painted. Ferrocement tanks are commonly used in some Pacific islands (e.g. Tonga, Tuvalu, Kiribati, Federated States of Micronesia) as they can be constructed by local contractors and community groups which often contributes to the sustainability of their operation and maintenance. In recent years, plastic tanks have become popular for household rainwater collection in many islands of the Pacific and in Maldives.

Runway rainwater catchment, Majuro, Marshall Islands

In addition to roof catchments, rainfall is sometimes collected from specially prepared surfaces. Examples are paved airport runways (e.g. Majuro, Marshall Islands) and specially prepared surfaces with adjacent storage tanks or artificially lined reservoirs (e.g. some islands in Torres Strait, between Australia and PNG). Simple rainwater collection systems consisting of containers (e.g. plastic barrels) located under the crown of coconut trees where rainfall concentrates, are still used in some islands (e.g. some outer islands of PNG).

'Non-conventional' water resources

Desalination

Desalination is another, but less common method of freshwater production. Desalination systems are based on a distillation or a membrane process. Distillation processes include multi-stage flash (MSF), multiple effect (ME) and vapour compression (VC). Membrane processes include reverse osmosis (RO) and electrodialysis (ED). The most common method used in small island countries is RO.

Desalination is a relatively expensive and complex method of obtaining freshwater for small islands. The cost of producing desalinated water is almost invariably higher than 'conventional' options (e.g. pumping of groundwater) due to the high energy and operating expenses.

The main drawback of desalination however, is the shortage of trained individuals and spare parts to maintain such systems. There are numerous examples of abandoned desalination plants throughout the Pacific. However, its selected use, especially in tourist resorts, can reduce the demand put upon conventional water resources.

Importation

Water importation has been employed for a number of islands, especially as an emergency measure during severe drought situations. Water has been imported by sea transport (boats, or barges) during droughts, for instance, to outer islands of Fiji and Tonga. Sometimes people on islands with a water shortage will travel by boat or canoe to nearby islands with more plentiful water sources.

'Bottled water' for Ebeye from Kwajalein, Marshall Islands ^

In many small islands, bottled water has become an alternative source of drinking water (either imported or made locally by desalination plants). Invariably, its cost is higher than water supplied by local water authorities.

Non-potable water sources

Non-potable water sources include seawater, brackish groundwater and treated wastewater.

There are many examples of the use of seawater and brackish waters in order to conserve valuable freshwater resources on small islands. For example, reticulated seawater is used for toilet flushing and as a source for fire-fighting in densely populated parts of Tarawa and Majuro. Dual pipe systems are used to distribute water to houses and other connections - one pipe system is for freshwater supply and the other for seawater. Seawater, or brackish well water, is often used for bathing and some washing purposes on small islands. Seawater is also used on some islands for cooling of electric power generation plants, for ice making and in swimming pools.

Treated wastewater is not a common non-potable source in small islands, but is sometimes reused for irrigation of garden and recreational areas at tourist resorts and hotels on some small islands (e.g. Fiji, Maldives).

Substitution

During severe drought conditions, or after natural disasters, coconut water has been used as a substitute for fresh drinking water. People on some of the smaller outer islands in Fiji, Kiribati, Marshall Islands and PNG, for instance, have survived on coconuts during drought periods. The coconut tree is very salt-tolerant and can continue to produce coconuts even when groundwater has turned brackish.

Summary of freshwater resources in the Pacific

Country or Territory	Main freshwater resources1	Main freshwater uses2
Pacific Island Countries
Cook Islands	SW, GW, RW	WS, T
Federated States of Micronesia	SW, GW, RW	WS
Fiji	SW, GW, RW, D (tourist resort only)	WS, T, H, I
Kiribati	GW, RW, D (limited)	WS
Marshall Islands	RW (from airport catchment and buildings), GW, D emergency)	WS
Nauru	D (regular use), RW, GW (limited)	WS
Niue	GW, RW WS
Palau	SW, GW, RW	WS
Papua New Guinea	SW, GW, RW	WS, M
Samoa	SW, GW, RW	WS
Solomon Islands	SW, GW, RW	WS
Tonga	GW, RW, SW (limited)	WS
Tuvalu	RW (primary), GW (limited), D (emergency)	WS
Vanuatu	SW, GW, RW	WS, T, H
Other Pacific islands (Territories of USA and France)
American Samoa	SW, GW, RW	WS
French Polynesia	SW, GW, RW, D	WS, T
Guam	SW, GW, RW, D	WS
New Caledonia	SW, GW, RW	WS, M
Island countries in other regions
East Timor	SW, GW, RW	WS
Maldives	D (main island of Mal GW, RW (outer islands)	WS

Notes:
1.SW = Surface water, GW = groundwater, RW = rainwater, D = desalination.
2.WS = water supply to communities, T = tourism, H = hydroelectricity, M = mining, I = irrigation