The Omo River, also known as Omo-Bottego, is the largest Ethiopian river outside the Nile Basin. Situated in southern Ethiopia, its entire course lies within the country's borders, eventually emptying into Lake Turkana on the border with Kenya. 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. 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.
The river's course generally flows south, marked by a significant westward bend around 7° N 37° 30' E, extending to approximately 36° E. Here, it shifts southward until reaching 5° 30' N, where it forms a large S-bend before resuming its southerly direction toward Lake Turkana.
Location of Ethiopia in Africa
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 Omo-Bottego River formed the eastern boundaries for the former kingdoms of Janjero, and Garo.
Historical Significance and Archaeological Discoveries
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. 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.
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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. This team located a number of different items, including the jawbone of an Australopithecus man, estimated at some 2.5 million years old. Archeologists have also found fossil fragments of Olduwan hominids from the early Pleistocene era and up to the Pliocene era.
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. 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.
Hydroelectric Power and Dams
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. The Gilgel Gibe II Power Station 7°45′23″N 37°33′45″E is a hydroelectric power station on the Omo River with a power output of 420 Megawatt (MW). The power station receives water from a tunnel entrance 7°55′27″N 37°23′16″E on the Gilgel Gibe River in a run-of-river scheme.
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The Gibe III Hydroelectric dam is a 243 metres (797 ft) high roller-compacted concrete dam with an associated hydropower plant on the Omo River in Ethiopia. It is the largest hydropower plant in Ethiopia with a power output of about 1870 Megawatt (MW), thus more than doubling total installed capacity in Ethiopia from its 2007 level of 814 MW.
A controversy has ensued over its construction, with several NGOs forming a campaign to oppose it. However, Azeb Asnake, project manager of Gibe III for the government power provider, said that a mitigation measure has been prepared in case something happens.
Impact of Dams and Plantations
Dams and irrigated plantations being built in Ethiopia will bring major changes to the flow of the Lower Omo River, which in turn will harm ecosystem functions and local livelihoods all the way to the river’s terminus at Lake Turkana in Kenya. Lower Omo River. Alison M. The Gibe III reservoir is expected to start filling in early 2015; filling the reservoir will take up to three years. The Gibe III will provide stable flows year-round that will enable the growth of large commercial agricultural plantations in the Lower Omo.
These projects will cause a decrease in river flow and the size, length, and number of floods, which will be disastrous for downstream users. Changes to the flooding regime will disrupt fish spawning cues and decrease productive habitat for fish in Lake Turkana and the river. Because the Omo River contributes almost all of Lake Turkana’s inflows each year, these developments could cause a big drop in lake water levels. Lake Turkana is projected to drop by about two meters during the initial filling of the dam. If current plans to create new plantations move forward, the lake could drop from 16 to 22 meters. The average depth of the lake is just 31 meters.
Tribes of the Omo Valley.mov
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Climate change could worsen the water situation in the Omo. More extreme droughts and unpredictable precipitation patterns, combined with higher temperatures (which increase evaporation), could cause further stress to a region that already experiences extreme precipitation variability.
In 2011 the government began to lease out vast blocks of fertile land in the Lower Omo region to Malaysian, Italian, Indian and Korean companies to plant biofuels and cash crops such as oil palm, jatropha, cotton and maize. It has started to evict Bodi, Kwegu, and Mursi people from their land into resettlement areas to make way for the large state-run Kuraz Sugar Project, covering 150,000 hectares but which could eventually cover 245,000 hectares. Communities’ grain stores, beehives and their valuable cattle grazing land have been destroyed.
Those who oppose the theft of their land have routinely been beaten and thrown in jail. The Bodi, Mursi and Suri have been told they have to give up their herds of cattle, a vital part of their livelihood, and may only keep a few cows in the resettlements, where they will become dependent on government aid to survive.
The Lower Omo Valley: A UNESCO World Heritage Site
The Lower Omo Valley is situated within Africa’s famous and, geologically-speaking, rapidly expanding Great Rift Valley (which will eventually split the continent into two landmasses). Here, in south-west Ethiopia’s awkwardly named “Southern Nations, Nationalities, and People’s Region”, bordering Kenya and Sudan, the great Omo River dominates this dry savanna valley, resulting in some of Africa’s most well developed and best preserved arid-zone riverine forests.
The Omo River rises from the Shewan highlands to the north (much of Ethiopia consists of high-lying mountains and fertile plateaus, despite the impression created by some international media bodies that Ethiopia is predominately desert!). It flows 470 miles, mostly southwards, before entering Lake Turkana (previously Lake Rudolf) near the Kenyan border.
The importance of the Lower Omo Valley has been recognized by UNESCO, who has declared it a cultural World Heritage Site. It also contains two massive national parks and several Important Bird Areas. This vast, scenic valley is now most famous for its staggering cultural diversity. Over a dozen distinctive ethnic groups exist here, many of whom live lives little touched by the modern world. Recent publicity about these remarkable tribes has resulted in tourists wanting to experience this wild land and its attractions for themselves.
The Lower Omo Valley is also famous for its significant anthropological discoveries, including hominid remains of several distinctive species, going back as far as four million years, as well as the earliest known skeletons of our own species (nearly 200,000 years old). Nearly 2,500 square miles of the wildest sections of the Omo Valley are protected in the almost contiguous Omo National Park on the river’s west bank (Ethiopia’s largest park) and Mago National Park on the east bank.
Tribal Life and the River's Importance
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. 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."
The Lower Omo Valley peoples make all public decisions after extensive community meetings among all adults. ‘Now the people live in fear - they are afraid of the government. In July 2009, the Southern Region’s Justice Bureau revoked the licences of 41 local ‘Community Associations’, accusing them of not co-operating with government policy.
They depend on it to practice ‘flood retreat cultivation’ using the rich silt left along the river banks by the slowly receding waters. They also practice rainfed, shifting cultivation growing sorghum, maize and beans on the flood plains. Cattle, goats and sheep are vital to most tribes’ livelihood producing blood, milk, meat and hides.
Tribal song from the Omo Valley. They are an important defence against starvation when rains and crops fail. In certain seasons families travel to temporary camps to provide new grazing for herds, surviving on milk and blood from their cattle. Despite this co-operation there are periodic conflicts as people compete for natural resources.
For years the tribes of the Lower Omo Valley have suffered from the progressive loss of access to and control of their lands. As the government has taken over more and more tribal land, competition for scarce resources has intensified.
The future of these tribal cultures faces considerable uncertainty. The end result will be a massive reduction in the volume of water flowing into the Lower Omo Valley and Lake Turkana, disrupting these delicate ecosystems and the annual flooding. Riverine forests will desiccate and the food security of an estimated 100,000 tribal people, who depend on the annual flooding for their livelihoods, will be severely threatened. A further 300,000 people who depend on Lake Turkana will also be adversely affected. This is predicted to result in intertribal conflicts and the destruction of their traditional way of life and culture.
Summary of Key Facts About the Omo River
| Fact | Details |
|---|---|
| Location | Southern Ethiopia, empties into Lake Turkana (Kenya border) |
| Length | Approximately 644 km (400 miles) |
| Significance | Largest Ethiopian river outside Nile Basin |
| Archaeological Importance | Rich in hominid and animal fossils dating back to the Pliocene and Pleistocene |
| Threats | Dams (Gibe III), irrigated plantations, climate change |
| Impacts | Reduced river flow, disrupted ecosystems, threatened local livelihoods |
| UNESCO World Heritage Site | Lower Omo Valley |
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