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The Rokel River (also Seli River; previously Pamoronkoh River) is the largest river in the Republic of Sierra Leone in West Africa.

River course

The Rokel rises in the 900 metres (3,000 ft) high interior plateau of the Loma Mountains, in the Guinea Highlands of north central Leone, flows southwest about 240 miles (390 km) through hill ranges and, together with a smaller, parallel stream called Port Loko Creek, feeds into the Rokel estuary before entering the Atlantic Ocean. The estuary, also called the Sierra Leone River, is 25 miles (40 km) in length and has a width varying from 4 miles (6.4 km) to 10 miles (16 km). Freetown and Pepel are the two ports located on the shores of the estuary. As the estuary widens and joins the Atlantic its width is about 11 km (6.8 mi). The southern shore is the deepest and forms a natural harbour, which is reported to be the third largest in the world.

Mangrove swamps and the mud flats are the dominant ecosystem (accounting for 19% of the mangrove forest in the country) noted around the river's ria. The river basin measures 10,622 square kilometres (4,101 sq mi) in size, with the drainage divided by the Gbengbe and Kabala hills and the Sula Mountains. The Rokel drops 15 metres (49 ft) at the Bumbuna waterfalls. Mangrove species recorded are Rhizophora, Avicennia, Laguncularia, and Conocarpus, which cover an area of 34.23 hectares (84.6 acres)/sec. Sierra Leone's capital city of Freetown lies at the entrance to the Sierra Leone River, about 25 miles (40 km) from the port of Pepel.

Geology

Rokel River and its tributaries are defined as Rakel River Group for geological study. The geological formation in this group is reported to be of the Tabe formation with glacial sediments dominating its eastern edge and are exposed along the river in some stretches; the geological formation noted in the river is granite rocks. The formation is broadly categorized as folded sedimentary rocks. It is also reported that its orogeny belongs to the Pan African thermo-tectonic age of about 550 Ma.

Geologically it is a tectonically controlled basin with formations of Precambrian, Infra-cambrian and Pleistocene age. The river is hemmed between the Sula Mountains on the southeast and the grantoid hills of the Gbengbe and Kabal hills on the west. The notable cascade in the river is known as the Bumbuna water falls where the river drops by 15 metres (49 ft)/sec providing for building a Hydroelectric project.

History

The estuary which extends over an area of 2,950 square kilometres (1,140 sq mi)/sec was proposed to be listed as a Ramsar site of wetland importance. The site is bounded by Cape Point on the Western Side of the Freetown, by the Bunce River on one of its banks, and the Targrin Point where areas of the Rokel joins at the southern end of its mouth. It was listed as Ramsar site in 1999.

Iron ore and alluvial gold mining began in the late 1920s and early 1930s, while the Bumbuna Falls hydroelectric project is underway. The Yalunka people established their capital, Falaba, near the source of the Rokel. Sierra Leone's equivalent of the British knighthood is called "Order of the Rokel."

Water resources development

The Rockel river flow has been measured at three gauge stations. The reported maximum and minimum discharge at Magbass, one of the three stations, are 1,905 cubic metres (67,300 cu ft)/sec and 2 cubic metres (71 cu ft)/sec respectively. There are many projects developed in the river basin which derive their water supply requirements from this river.

Flora and fauna

The flora in the estuary consists of Mangove forest. The avi fuana in the area consists of 10,000 birds of 36 species (1995 record). It is also reported that there are eight winter wader species reported to account for 1% of its world population. The eight species of palaearctic migrant waders recorded are

• Ringed Plover (Charadrius hiaticula)
• Kentish Plover (Pluvialis squatarola)
• Sanderling (Calidris alba)
• Curlew Sandpiper (Calidris ferruginea)
• Whimbrel (Numeniusphaeopus)
• Green Shank (Tringa nebularia)
• Red Shank (Tringa totanus)
• Western Reef Heron (Egrette gularis)

References

1. ^ Bird, Eric (8 April 2010). Encyclopedia of the World's Coastal Landforms. Springer. pp. 933–. ISBN 978-1-4020-8638-0.
2. "Rokel River". Encyclopedia Brittanica. Retrieved 3 July 2013.
3. "Sierra Leone River". Encyclopedia Brittanica. Retrieved 3 July 2013.
4. ^ "Sierra Leone Estuary :Proposed Ramsar Site" (pdf). Wetland Organization. Retrieved 3 July 2013.
5. ^ Brebbia, C. A.; Popov, V. (1 April 2013). Food and Environment II: The Quest for a Sustainable Future. WIT Press. pp. 45–. ISBN 978-1-84564-703-2.
6. M. J. Hambrey; W. B. Harland (14 April 2011). Earth's Pre-Pleistocene Glacial Record. Cambridge University Press. pp. 132–133. ISBN 978-0-521-17230-1. Retrieved 3 July 2013.
7. ^ Rosbjerg 1997, p. 496. sfn error: no target: CITEREFRosbjerg1997 (help)
8. Shillington, Kevin (2004). Encyclopedia of African History. CRC Press. pp. 922–. ISBN 978-1-57958-245-6.

8°33′N 12°48′W / 8.55°N 12.80°W / 8.55; -12.80

• Rivers of Sierra Leone