Geography of Tuvalu - Geography and Environment

Geography and Environment

Tuvalu consists of three reef islands and six true atolls. Its small, scattered group of atolls have poor soil and a total land area of only about 26 square kilometres (less than 10 sq. mi.) making it the fourth smallest country in the world. The islets that form the atolls are very low lying. Nanumaga, Niutao, Niulakita are reef islands and the six true atolls are Funafuti, Nanumea, Nui, Nukufetau, Nukulaelae and Vaitupu. Funafuti is the largest atoll of the nine low reef islands and atolls that form the Tuvalu volcanic island chain. It comprises numerous islets around a central lagoon that is approximately 25.1 kilometres (15.6 mi) (N–S) by 18.4 kilometres (11.4 mi) (W-E), centred on 179°7’E and 8°30’S. On the atolls an annular reef rim surrounds the lagoon, with several natural reef channels.

The eastern shoreline of Funafuti Lagoon was modified during WW-II when the airfield (what is now Funafuti International Airport) was constructed. As well several piers were constructed, beach areas filled, and deep water access channels were excavated. These alternations to the reef and shoreline have resulted in changes to wave patterns with less sand accumulating to form the beaches as compared to former times; and the shoreline is now exposed to wave action. Several attempts to stabilize the shoreline have not achieved the desired effect. The reefs at Funafuti have suffered damage, with 80 per cent of the coral having been bleached as a consequence of the increase of the ocean temperatures and acidification from increased levels of carbon dioxide. Researchers from Japan have investigated rebuilding the coral reefs through introduction of foraminifer.

The highest elevation is 4.6 metres (15 ft) above sea level on Niulakita, which gives Tuvalu the second-lowest maximum elevation of any country (after the Maldives). However, the highest elevations are typically in narrow storm dunes on the ocean side of the islands which are prone to over topping in tropical cyclones, such as occurred with Tropical Cyclone Bebe.

Tuvalu is mainly composed of coral debris eroded from encircling reefs and pushed up onto the islands by winds and waves. Paul Kench at the University of Auckland in New Zealand and Arthur Webb at the South Pacific Applied Geoscience Commission in Fiji released a study in 2010 on the dynamic response of reef islands to sea level rise in the central Pacific. Tuvalu was mentioned in the study, and Webb and Kench found that seven islands in one of its nine atolls have spread by more than 3 per cent on average since the 1950s. One island, Funamanu, gained 0.44 hectares, or nearly 30 per cent of its previous area.

Because of the low elevation, the islands that make up this nation are threatened by current and future sea level rise. Additionally, Tuvalu is annually affected by king tide events which peak towards the end of the austral summer, and raise the sea level higher than a normal high tide. As a result of historical sea level rise, the king tide events lead to flooding of low lying areas, which is compounded when sea levels are further raised by La Niña effects or local storms and waves. In the future, sea level rise may threaten to submerge the nation entirely as it is estimated that a sea level rise of 20–40 centimetres (8–16 inches) in the next 100 years could make Tuvalu uninhabitable.

Tuvalu experiences westerly gales and heavy rain from October to March - the period that is known as Tau-o-lalo; with tropical temperatures moderated by easterly winds from April to November. Drinking water is mostly obtained from rainwater collected on roofs and stored in tanks; these systems are often poorly maintained, resulting in lack of water. Aid programs of Australia and the European Union have been directed to improving the storage capacity on Funafuti and in the outer islands.

The rising population results in increased demand on fish stocks, which are under stress; although the creation of the Funafuti Conservation Area has provided a fishing exclusion area that helps sustain fish populations across the Funafuti lagoon. Population pressure on the resources of Funafuti and in-adequation sanitation systems have resulted in pollution. The Waste Operations and Services Act 2009 provides the legal framework for the waste management and pollution control projects funded by the European Union that are directed to organic waste composting in eco-sanitation systems. Plastic waste is also a problem as much imported food and other commodities is supplied in plastic containers or packaging.

When the airfield at Funafuti was constructed during WW-II the coral base of the atoll was used as fill to create the runway; the resulting borrow pits impacted on the water aquifer; at these pits the sea water can be seen bubbling up through the porous coral rock to form pools on each high tide.

Environment - current issues: since there are no streams or rivers and groundwater is not potable, most water needs must be met by catchment systems with storage facilities; beachhead erosion because of the use of sand for building materials; excessive clearance of forest undergrowth for use as fuel; damage to coral reefs from the bleaching of the coral as a consequence of the increase of the ocean temperatures and acidification from from increased levels of carbon dioxide; Tuvalu is very concerned about global increases in greenhouse gas emissions and their effect on rising sea levels, which threaten the country's underground water table.

See also: Funafuti Conservation Area and 2011 Tuvalu drought

El Niño and La Niña: Tuvalu experiences the effects of El Niño and La Niña that flow from changes in ocean temperatures in equatorial and central Pacific. El Niño effects increase the chances of tropical storms and cyclones; while La Niña effects increase the chances of drought conditions in Tuvalu. On 3 October 2011, drought conditions resulted in a state of emergency being declared as water reserves ran low. Typically the islands of Tuvalu receive between 200mm to 400mm of rainfall per month, however a weak La Niña effect caused a drought by cooling the surface of the sea around Tuvalu.

Environment - international agreements:
party to: Biodiversity, Climate Change, Climate Change-Kyoto Protocol, Desertification, Law of the Sea, Ozone Layer Protection, Ship Pollution, Whaling
signed, but not ratified: none