Lake Rudolf

Lake Turkana () is a saline lake in the Kenyan Rift Valley, in northern Kenya, with its far northern end crossing into Ethiopia. It is the world's largest permanent desert lake and the world's largest alkaline lake. By volume it is the world's fourth-largest salt lake after the Caspian Sea, Issyk-Kul, and Lake Van (passing the shrinking South Aral Sea), and among all lakes it ranks 24th.

Lake Turkana is now threatened by the construction of the Gilgel Gibe III Dam in Ethiopia due to the damming of the Omo river which supplies most of the lake's water.

Although the lake commonly has been—and to some degree still is—used for drinking water, its salinity (slightly brackish) and very high levels of fluoride (much higher than in fluoridated water) generally make it unsuitable for drinking directly, and it has also been a source of diseases spread by contaminated water. Increasingly, communities on the lake's shores rely on underground springs for drinking water. The same characteristics that make it unsuitable for drinking, limit its use in irrigation. The climate is hot and very dry.

The rocks of the surrounding area are predominantly volcanic. Central Island is an active volcano, emitting vapour. Outcrops and rocky shores are found on the east and south shores of the lake, while dunes, spits and flats are on the west and north, at a lower elevation.

On-shore and off-shore winds can be extremely strong, as the lake warms and cools more slowly than the land. Sudden, violent storms are frequent. Three rivers (the Omo, Turkwel and Kerio) flow into the lake, but lacking outflow, its only water loss is by evaporation. Lake volume and dimensions vary. For example, its level fell by between 1975 and 1993. Despite the lack of outflow, in ecology it is often regarded as a part of—or at least associated with—the Nile basin because of its prehistoric connection to this system and the similarities in their aquatic faunas.

Due to local temperatures (its surface water typically is , and the mean air temperature of the region generally is similar or slightly higher), aridity and geographic inaccessibility, the lake retains its wild character. Nile crocodiles are found in great abundance on the shore flats. The rocky shores are home to scorpions and carpet vipers. The lake is rich in fish and fishing is very important to the local economy, but this is threatened by falling water levels and overfishing.

Lake Turkana National Parks are now listed as a UNESCO World Heritage Site. Sibiloi National Park lies on the lake's eastern shore, while Central Island National Park and South Island National Park lie in the lake. Both are known for their Nile crocodiles.

An abundance of hominid fossils have been discovered in the area surrounding Lake Turkana.

The area still sees few visitors, being two days' drive from Nairobi. The lake is also an imaginary boundary of the Rendille and Borana and Oromo to the Turkana land. The area is primarily clay-based and is more alkaline than seawater.

Toponymy

After the independence of Kenya, the president, Mzee Jomo Kenyatta, renamed it in 1975 after the Turkana, the predominant tribe there. The Turkana refer to the lake as ''Anam Ka'alakol'', meaning "the sea of many fish". It is from the name Ka'alakol that Kalokol, a town on the western shore of Lake Turkana, east of Lodwar, derives its name. The previous indigenous Turkana name for Lake Turkana was ''Anam a Cheper''. Natives who live around Lake Turkana include the Turkana, Rendille, Gabbra, Daasanach, Hamar Koke, Karo, Nyagatom, Mursi, Surma, and Molo peoples. For the location of many of these peoples, refer to the dialect map in the article.

Lake Rudolf

The lake was originally named Lake Rudolf (in honour of Crown Prince Rudolf of Austria) by Count Sámuel Teleki de Szék and his second-in-command Lieutenant Ludwig Ritter Von Höhnel, a Hungarian and an Austrian, on 6 March 1888. They were the first Europeans to have recorded visiting the lake after a long safari across East Africa. The lake kept its European name during the colonial period of British East Africa. However, the existence of the lake and its shape and location were well known in Europe long before Teleki conceived of his visit.

Jade Sea

At some unknown time, the lake acquired an alternative name as the ''Jade Sea'' from its turquoise colour seen approaching from a distance. The colour comes from algae that rise to the surface in calm weather. This is likely also a European name.

Basso Narok

J. W. Gregory reported in ''The Geographical Journal'' of 1894 that it was called "Basso Narok", meaning "Black Lake" in the Samburu language. Likewise, the nearby Ethiopian Lake Chew Bahir is called "Basso Naibor" in Samburu, meaning "White Lake". The Samburu are among the dominant tribes in the lake Turkana region when the explorers came." What the native form of this phrase was, what it might mean, and in which language is not clear.

Biology

Biomes

The major biomes are the lake itself, which is an aquatic biome, and the surrounding region, which is classified as desert and xeric shrubland. The Chalbi Desert is east of the lake. During moister times, a dry grassland appears, featuring ''Aristida adcensionis'' and ''A. mutabilis''. During drier times, the grass disappears. The shrublands contain dwarf shrubs, such as '' Duosperma eremophilum'' and ''Indigofera spinosa''. Near the lake are doum palms.

Plankton

Both phytoplankton and zooplankton are found in the lake.Th
World Lakes Database
includes mention of the lake plankton, some of which are responsible for its turquoise colour. Of the former, cyanobacteria are represented by ''Microcystis aeruginosa'' and microalgae by ''Botryococcus braunii''. Also present are '' Anabaenopsis arnoldii'', '' Planctonema lauterbornii'', ''Oocystis gigas'', '' Sphaerocystis schroeteri'', and some others. The zooplankton includes copepods, cladocerans and protozoans.

Fish

Compared to other large African lakes, Turkana has relatively few fish species. The lake holds about 50 fish species, including 12 endemics: the cichlids '' Haplochromis macconneli'', '' H. rudolfianus'', '' H. turkanae'' and '' Hemichromis exsul'', the barb '' Enteromius turkanae'', the catfish '' Chrysichthys turkana'', the robber tetras '' Brycinus ferox'' and '' B. minutus'', the Rudolf lates '' Lates longispinis'', the lampeyes ''Lacustricola jeanneli'' and '' Micropanchax rudolfianus'', and the cyprinid '' Neobola stellae''.Freshwater Ecoregions of the World (2008).
Lake Turkana.
'' Accessed 2 May 2011 Non-endemics include species such as Nile tilapia, mango tilapia, bichirs, the elephantfish '' Mormyrus kannume'', African arowana, African knifefish, '' Distichodus niloticus'', the Nile perch and numerous others. During the early Holocene, the water level of the lake was higher, and it overflowed into the Nile River, allowing fish and crocodiles access. Consequently, the non-endemic fishes in the lake are mainly riverine species of Nilotic origin. Some of the non-endemics do not breed in the lake, but migrate up the Omo River and other affluents to breed. The lake is heavily fished.

Birds

The Lake Turkana region is home to hundreds of species of birds native to Kenya. The East African Rift System also serves as a flyway for migrating birds, bringing in hundreds more. The birds are essentially supported by plankton masses in the lake, which also feed the fish.

Some birds more common to Turkana are the little stint, the wood sandpiper, and the common sandpiper. The African skimmer (''Rhyncops flavirostris'') nests in the banks of Central Island. The white-breasted cormorant (''Phalacrocorax lucidus'') ranges over the lake, as do many other waterbirds. The greater flamingo wades in its shallows. Heuglin's bustard (''Neotis heuglinii'') is found in the east of the lake region.

Reptiles

The lake formerly contained Africa's largest population of Nile crocodiles: 14,000, as estimated in a 1968 study by Alistair Graham.

The lake also has a large population of large water turtles, particularly in the area of Central Island. The Turkana mud turtle is endemic to the lake.

Mammals

Over the dry grasslands ranges a frail population of grazing mammals and predators. The grazers are chiefly Grevy's zebra, Burchell's zebra, the beisa oryx, Grant's gazelle, the topi and the reticulated giraffe. They are hunted by the lion and the cheetah. Elephants and the black rhinoceroses are no longer seen, although Teleki reported seeing (and shooting) many. Closer to the dust is the cushioned gerbil (''Gerbillus pulvinatus'').

Geology

Lake Turkana is an East African Rift feature. A rift is a weak place in the Earth's crust due to the separation of two tectonic plates, often accompanied by a graben, or trough, in which lake water can collect. The rift began when East Africa, impelled by currents in the mantle, began separating from the rest of Africa, moving to the northeast. Currently, the graben is 320 km wide in the north of the lake, 170 km in the south. This rift is one of two, and is called the Great or Eastern Rift. There is another to the west, the Western Rift.

Lake Turkana is a unique feature of the East African landscape. Besides being a permanent desert lake, it is the only lake that retains the waters originating from two separate catchment areas of the Nile. The Lake Turkana drainage basin draws its waters mainly from Kenya Highlands and Ethiopian Highlands.

The basement rocks of the region have been dated by two analytical determinations to 522 and 510 million years ago (mya). No rift was in the offing at that time. A rift is signalled by volcanic activity through the weakened crust. The oldest volcanic activity of the region occurred in the Nabwal Hills northeast of Turkana and is dated to 34.8 mya in the late Eocene.

The visible tectonic features of the region result from extensive extrusions of basalt over the Turkana-Omo basin in the window 4.18–3.99 mya. These are called the Gombe Group Basalts. They are subdivided into the Mursi Basalts and the Gombi Basalts.

The two latter basalts are identified as the outcrops forming the rocky mountains and badlands around the lake. In the Omo portion of the basin, of the Mursi Basalts, the Mursi Formation is on the west side of the Omo, the Nkalabong on the Omo, and the Usno and Shungura east of the Omo. Probably the best known of the formations are the Koobi Fora on the east side of Turkana and the Nachukui on the west.

Short-term fluctuations in lake level combined with periodic volcanic ash spewings over the region have resulted in a fortuitous layering of the ground cover over the basal rocks. These horizons can be dated more precisely by chemical analysis of the tuff. As this region is believed to have been an evolutionary nest of hominins, the dates are important for generating a diachronic array of fossils, both hominoid and nonhominoid—that is, both ''ape (includes hominins)'' and ''non-ape''. Many thousands have been excavated.

Terraces representing ancient shores are visible in the Turkana Basin. The highest is 100 m above the surface of the lake (only approximate, as the lake level fluctuates), which occurred about 9500 years ago, at the end of the Pleistocene as part of the African humid period. It is generally theorised that Turkana was part of the upper Nile system at that time, connecting to Lake Baringo at the southern end and the White Nile in the north, and that volcanic land adjustments severed the connection. Such a hypothesis explains the Nile species in the lake, such as the crocodiles and the Nile perch. High water levels also occurred approximately 9000, 6000 and 5000 years ago, each of which were followed by drops in lake level of more than 40m in less than 200 years. It is thought that changes in the position of the Congo Air Boundary affected the ability of moisture from the Atlantic Ocean to reach eastern Africa, which had a profound influence on the level of Lake Turkana and adjacent water bodies.

The archaeoastronomical site Namoratunga, which has been dated to circa 300 BCE, is located near Lake Turkana.

Anthropology

Hominin fossils of some of the earliest human ancestors have been found in the Turkana Basin. Lake Turkana is considered the cradle of human life because of the diverse hominid species found living millions of years apart in this desert landscape. These fossils have facilitated human understanding of the dynamic human evolution process and imply that they descended from more than one common ancestor, diverging into multiple lineages.

The changing forest environment forced the early humans to adapt to a more open grassland that increased their exposure to threatening predators. Volcanic ash and drier climates were ideal for preserving these human fossils but it also caused the lake to shrink or disappear at times. 

In a dry riverbed, the Lomekwi 3 site recovered primitive hammers, anvils, and cutting tools. However, the emergence of Acheulean technology no longer assumes that tool use was a distinguishing factor among ''Homo'' species as Australopithecus afarensis were also using simple tools prior to the appearance of the genus ''Homo'', over 3.3 million years ago.

''Australopithecus anamensis'' fossils discovered by Meave Leakey in 1994 date to around 4 million years ago, setting the beginning date of bipedalism back half a million years. Richard Leakey has led numerous anthropological expeditions in the area which have led to many important discoveries of hominin remains.

The two-million-year-old skull 1470 was found in 1972. It was originally thought to be ''Homo habilis'', but the scientific name ''Homo rudolfensis'', derived from the old name of this lake (Rudolf) was proposed in 1986 by V. P. Alexeev. In 1984, the Turkana Boy, a nearly complete skeleton of a ''Homo ergaster'' juvenile, was discovered by Kamoya Kimeu. More recently, Meave Leakey discovered a 3.5 million-year-old skull there, designated '' Kenyanthropus platyops'' ("the flat-faced man of Kenya").

Marta Mirazón Lahr discovered early evidence of human warfare at the site of Nataruk, located near the shore of an ancient and larger Lake Turkana, and where numerous human skeletons showing major traumatic injuries to the head, neck, ribs, knees and hands are argued to be evidence of inter-group conflict between nomadic hunter-gatherers 10,000 years ago. With over 230 individuals found at the Koobi Fora site along the western shore, and scattered ''Homo sapiens'' skeletons with bone marks along the eastern shore at the Nataruk Site, this region provides considerable insight to the way these early humans thrived and survived the inconsistent climate along the lake shore and beyond. 

''Homo erectus'' is the closest of ''Homo sapiens'' ancestors and contended to be the first hominin to cross the Levantine corridor out of Africa into Europe and Asia 1.8 million years ago.

Many language groups are represented in the area around Lake Turkana, which is evidence for numerous migrations of diverse people over thousands of years. The current language groups include at least three separate subgroups of the Nilotic (Nilo-Saharan) and Cushitic (Afro-Asiatic) language families, which have further subdivided into more than 12 languages surrounding the lake today. In the early Holocene (during the Holocene Climatic Optimum), lake levels were high and fishing and foraging were the primary subsistence economies. This was mostly supplanted by animal-based agriculture by 5000 years ago, when the lake level was in a period of rapid fluctuation. During the later Holocene, human responses to climatic changes included intensive fishing when lake level was high and a shift to cattle herding when the level dropped. Megalithic graves are found widely distributed on the lake shores and appear to correspond to the period when domesticated animals were first introduced to the region about 5000 years ago, while later, the dead were buried in small grave cairns. People who live in the region today commonly practice mixed subsistence, switching between hunting, fishing and animal herding based on what is feasible in a given year. However, the construction of infrastructure like Christian missionary stations, energy extraction (wind, oil) and NGO aid distribution points have made the region more connected to and dependent on outside resources for subsistence. Traditional modes of subsistence like pastoralism and fishing are now supplemented by the cash-based economy.

Wind power

The Lake Turkana Wind Power consortium (LTWP) plans to provide 310 MW of power to Kenya's national electricity grid by tapping the unique wind conditions around the lake. The plan calls for 365 wind turbines, each with a nameplate capacity

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