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. Nanumanga, 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 miles) (N–S) by 18.4 kilometres (11.4 miles) (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 World War II when the airfield (what is now Funafuti International Airport) was constructed. Several piers were also constructed, beach areas were filled and deep water access channels were excavated. These alterations to the reef and shoreline 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 becoming bleached as a consequence of the increase in ocean temperatures and acidification from increased levels of carbon dioxide. A reef restoration project has investigated reef restoration techniques; and researchers from Japan have investigated rebuilding the coral reefs through the introduction of foraminifer. The project of the Japan International Cooperation Agency is designed “o increase the resilience of the Tuvalu coast against sea level rise through ecosystem rehabilitation and regeneration and through engineering support for sand production and sedimentation processes.”

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 overtopping in tropical cyclones, as occurred with Tropical Cyclone Bebe.

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 mainly obtained from rainwater collected on roofs and stored in tanks. These systems are often poorly maintained, resulting in a lack of water. Aid programmes of Australia and the European Union have been directed to improving the storage capacity on Funafuti and in the outer islands.

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

When the World War II airfield at Funafuti was constructed, the coral base of the atoll was used as fill to create the runway. The resulting borrow pits impacted the water aquifer. At these pits, the sea water can be seen bubbling up through the porous coral rock to form pools with each high tide.