Omo River

Omo River Delta

The Omo River forms through the confluence of the Gibe River, by far the largest total tributary of the Omo River, and the Wabe River, the largest left-bank tributary of the Omo at 8°19′N 37°28′E. Given their sizes, lengths and courses one might consider both the Omo and the Gibe rivers to be one and the same river but with different names. Consequently, the whole river basin is sometimes called the Omo-Gibe River Basin. This river basin includes part of the western Oromia Region and the middle of the Southern Nations, Nationalities, and People's Region.

Its course is generally to the south, however with a major bend to the west at about 7° N 37° 30' E to about 36° E where it turns south until 5° 30' N where it makes a large S- bend then resumes its southerly course to Lake Turkana. According to materials published by the Ethiopian Central Statistical Agency, the Omo-Bottego River is 760 kilometres (470 mi) long.[2]

In its course the Omo-Bottego has a total fall of about 700 metres (2,300 ft) from the confluence of the Gibe and Wabe rivers at 1,060 metres (3,480 ft) to 360 metres (1,180 ft) at lake-level, and is consequently a rapid stream in its upper reaches, being broken by the Kokobi and other falls, and navigable only for a short distance above where it empties into Lake Turkana, one of the lakes of the Gregory Rift. The Spectrum Guide to Ethiopia describes it as a popular site for white-water rafting in September and October, when the river is still high from the rainy season.[3] Its most important tributary is the Gibe River; smaller tributaries include the Wabi, Denchya, Gojeb, Mui and Usno rivers.

The Omo-Bottego River formed the eastern boundaries for the former kingdoms of Janjero, and Garo. The Omo also flows past the Mago and Omo National Parks, which are known for their wildlife.[4] Many animals live near and on the river, including hippopotamuses, crocodiles and puff adders.

Omo river crossing

The entire Omo river basin is also important geologically and archaeologically. Over 50,000 fossils have been identified from the lower valley, including 230 hominid fossils dating to the Pliocene and Pleistocene.[5] Fossils belonging to the genera Australopithecus and Homo have been found at several archaeological sites, as well as tools made from quartzite, the oldest of which date back to about 2.4 million years ago.[1] When they were discovered, it was thought that the tools might have been part of a so-called pre-Oldowan industry, even more primitive than what was found in the Olduvai Gorge. Later research has shown that the crude looks of the tools were in fact caused by very poor raw materials, and that the techniques used and the shapes permit their inclusion in the Oldowan.

The first archaeological discoveries in the area were in 1901, by a French expedition. The most significant finds were made later, between 1967 and 1975, by an international archaeological team.[4] This team located a number of different items, including the jawbone of an Australopithecus man, estimated at some 2.5 million years old.[6][4] Archeologists have also found fossil fragments of Olduwan hominids from the early Pleistocene era and up to the Pliocene era. Quartz tools have been located with some of the later Homo sapiens remains found on the riverbanks.[4] Since then, the excavations have been carried out by a joint French and American team.[7]

In addition to early hominid fossils, a diversity of mammal[7] and fish[8] fossils have been found within the Omo Valley.[5]

Omo River Valley

The lower valley of the Omo is currently believed by some to have been a crossroads for thousands of years as various cultures and ethnic groups migrated around the region. To this day, the people of the Lower Valley of the Omo, including the Mursi, Suri, Nyangatom, Dizi and Me'en, are studied for their diversity.[9]

Italian explorer Vittorio Bottego first reached the Omo river on 29 June 1896 during his second African expedition (1895–97), dying during this expedition on 17 March 1897. The Omo river was renamed Omo-Bottego in his honour. Herbert Henry Austin and his men reached the Omo delta on 12 September 1898, and found that an Ethiopian expedition, led by Ras Wolda Giyorgis, had previously planted Ethiopian flags on the northern shore of Lake Turkana on 7 April, as well as having plundered the locals and reduced them to poverty. Lieutenant Alexander Bulatovich led a second Ethiopian expedition which reached the lake August 21, 1899, and was equally destructive. Despite this, the Frenchmen in the party accurately mapped for the first time many of the meanders of the Omo River delta. This rendition of the Omo River remained in use until the 1930s when Italian colonial cartographers made a new and more accurate rendition of the river and its delta.[10]

There are several power stations and dams in the Omo River basin which are named after the Gilgel Gibe River and Gibe River, which are tributaries of the Omo River. Despite the somewhat confusing naming they are native power stations and dams located on the Omo River.

Heavy rains in 2006 caused the Omo to flood its lower course, drowning at least 456 people and stranding over 20,000 people over the space of five days ending 16 August. While seasonal heavy rains are normal for this part of the country, overgrazing and deforestation are blamed for this tragedy. "The rivers in Ethiopia have less capacity to hold as much water as they did years before, because they are being filled up with silt," World Food Programme spokeswoman Paulette Jones said. "It takes less intensity of rainfall ... to make a river in any particular part of the country overflow."[17] The seasonal flooding of the Omo River is vital to the indigenous groups that live along it. The flood brings fertile silt and inundates the banks with water, making river bank cultivation possible. The diverse peoples along the lower Omo—which include the Turkana, Dassanach, Hamer, Nyangatom, Karo, Kwegu, Mursi, Bodi, and Me'en—derive a great portion of their food supply from flood retreat cultivation.[18]

The large and destructive flood of 2006 is the only one that has occurred within the past fifty years. The recent drop in the level of Lake Turkana, which is generally recognized to receive about ninety percent of its waters from the Omo River's inflow, has already caused a rise in salinity level. The increased size of the delta, now about 1,300 square kilometres (500 sq mi) in extent, has provided lands for recessional cultivation and pasture for cattle and other domestic livestock of the pastoralists and agro-pastoralists indigenous to the lower Omo basin.

Karo woman and child near Omo River

• Gibe River
• List of Ethiopian rivers
• List of fossil sites (with link directory)
• Omo Kibish Formation
• Omo Remains
• List of World Heritage Sites in Ethiopia

• Butzer, Karl W. (1971). Recent history of an Ethiopian delta: the Omo River and the level of Lake Rudolph, Research paper 136, Department of Geography, University of Chicago, 184 p., LCCN 70-184080
• Camerapix (2000). Spectrum Guide to Ethiopia, First American Ed., Brooklyn: Interlink, ISBN 1-56656-350-X
• Crandall, Ben (2007). The Omo River Valley, eMuseum @ Minnesota State University, Mankato; website accessed 31 October 2007
• Hurd, W. (2006). "Rangers by Birth", Cultural Survival Quarterly, 30.2, website accessed 31 October 2007
• UNESCO World Heritage Centre (2007). Lower Valley of the Omo, World Heritage List, website accessed 31 October 2007
• Vannutelli, L. and Citerni, C. (1899). Seconda spedizione Bòttego: L'Omo, viaggio d'esplorazione nell'Africa Orientale, Milano : Hoepli, 650 p.

Wikimedia Commons has media related to Omo River.

Wikimedia Commons has media related to Omo River.

• Omo National Park
• The African Tribes of OMO
• Africa Resources Working Group Gibe III Dam Omo River
• https://www.youtube.com/watch?v=9PUSPE_7ek8&t=4s Walking With The Mursi is an adventure/travel documentary spanning four continents as David Willing hikes 500km across Ethiopia's remote Omo Valley, home of the fascinating Mursi tribes.