The Fly River is the third longest river in the island of New Guinea, after the Sepik River and

Mamberamo River The Mamberamo (''Indonesian: Sungai Mamberamo'') is the second longest river on the island of New Guinea, after Sepik River (1,146 km) and third largest in Oceania by discharge (5,500 m3/s) volume after Fly River (7,500 m3/s) and Sepik (7,000 m3/ ...

, with a total length of and the largest by volume of discharge in Oceania, the largest in the world without a single dam in its catchment, and overall the 20th-largest primary river in the world by discharge volume. It is located in the southwest of Papua New Guinea and

Papua Province Papua is a province of Indonesia, comprising the northern coast of Western New Guinea together with island groups in Cenderawasih Bay to the west. It roughly follows the borders of Papuan customary region of Tabi Saireri. It is bordered by ...

of Indonesia. It rises in the Victor Emanuel Range arm of the

Star Mountains The Star Mountains (Dutch (colonial)'': Sterrengebergte''; Indonesian'': Pegunungan Bintang'') are a mountain range in western Papua New Guinea and the eastern end of Highland Papua, Indonesia, stretching from the eastern end of Indonesia to the ...

, and crosses the south-western lowlands before flowing into the Gulf of Papua in a large delta. The Fly-Strickland River system has a total length of making it the longest river system of an island in the world, including Strickland River is the longest and largest tributary of Fly River, making it the farthest distance source of the Fly River.

Description

The Fly flows mostly through the Western Province of Papua New Guinea and for a small stretch, it forms the

international boundary Borders are usually defined as geographical boundaries, imposed either by features such as oceans and terrain, or by political entities such as governments, sovereign states, federated states, and other subnational entities. Political borders ca ...

with western New Guinea. This section protrudes slightly to the west of the 141°E longitude line. To compensate for this slight gain in territory for Papua New Guinea, the border south of the Fly River is slightly east of the 141°E longitude line. As part of this deal, Indonesia has the right to use the Fly River to its mouth for navigation. The principal tributaries of the Fly are the Strickland and the Ok Tedi.

Close to its mouth, the flow of the Fly River encounters a tidal bore, where an incoming high tide pushes water upstream until the tide changes. The range of this tidal bore is still undocumented.

Delta

The delta of the Fly River is over 100 km wide at its entrance, but only 11 km wide at the apex upstream of Kiwai Island. The delta contains 3 main distributary channels (the Southern, Northern, and Far Northern Entrances) that branch from a common point (the “apex”). The distributary channels are 5 to 15m in depth, separated by elongate, sand-mud islands that are stabilised by lush mangrove vegetation. The islands are eroded and rebuilt rapidly in the apex area, where they have lateral migration rates of up to 150 m/a, with slower rates for the more seaward islands. Upstream from the apex the river gradually narrows to a width of 1.6 km or less. The Fly Delta exhibits a distinctive funnel shape in plan view, attesting to the fundamental role of tidal currents in shaping the Delta's geomorphology. Mean spring tidal ranges are amplified within the delta, from around 3.5m at the seaward entrance of the distributary channels, reaching a peak of about 5m at the delta apex. Seismic profiles and radiometrically dated core samples indicate that the delta is prograding seawards at an average rate of about 6 m/a The Fly Delta is considered as a global "type case" of a tide-dominated delta and the patterns of sedimentation seen in the Delta today have been studied by sedimentary geologists as a model for interpreting the ancient rock record The river delta is studded with low and swampy islands covered with mangrove and nipa palm, with villages and cultivated areas on these islands. The land on both sides of the estuary is of the same character. The islands in the estuary are flat and covered with thick, fertile alluvial soil. The largest islands are Kiwai Island, Purutu Island, Wabuda Island, Aibinio Island, Mibu Island, and Domori Island. Kiwai, Wabuda and Domori are inhabited. A list of the river delta islands is: The inhabitants of the Fly River delta engage in agriculture and hunting. Coconut palm, breadfruit, plantain, sago palm, and sugar cane are grown.

Fly River turtle

The Fly River turtle, also known as the Pig-nosed turtle due to its odd nose, is notably different from other turtles due to its piglike nose. The only freshwater turtle to have flippers, the turtle is known to rarely leave water, except in dire circumstances. They are also known to be omnivores who rarely consume meat.

History

The Fly was first discovered by Europeans in 1845 when Francis Blackwood, commanding the

corvette A corvette is a small warship. It is traditionally the smallest class of vessel considered to be a proper (or " rated") warship. The warship class above the corvette is that of the frigate, while the class below was historically that of the slo ...

HMS ''Fly'', surveyed the western coast of the Gulf of Papua. The river was named after his ship and he proclaimed that it would be possible for a small steam-powered boat to travel up the mighty river. In 1876, Italian explorer, Luigi D'Albertis, was the first person to successfully attempt this when he travelled 900 km into the interior of New Guinea, in his steamer, ''Neva''. It was the furthest any European explorer had ever been into the island.

Environmental issues

Both the Strickland and the Ok Tedi Rivers have been the source of environmental controversy due to tailings waste from the Porgera Mine and the Ok Tedi Mine, respectively. Sediment sampling and coring in the distributary channels of the Fly Delta had not detected copper concentrations significantly higher than background as of 1994. In 2008, Ian Campbell, a former advisor to Ok Tedi Mining Limited, claimed that company data suggest significant portions of the Fly River floodplain are at a high risk from acid mine drainage.

References