Lake Turkana
Lake Turkana is a saline lake in the Kenyan Rift Valley, in northern Kenya, the far northern end crosses 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, and among all lakes it ranks 22nd.
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 and very high levels of fluoride generally make it unsuitable for drinking, it has also been a source of diseases spread by contaminated water. Increasingly, communities around the lake rely on underground springs for drinking water. The same characteristics that make it unsuitable for drinking, limit its use for 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 southern 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 flow into the lake, but lacking outflow, its only water loss is by evaporation. Lake volume and dimensions vary. For example, the 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,, due to 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 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 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 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. 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. 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 nests in the banks of Central Island. The white-breasted cormorant ranges over the lake, as do many other waterbirds. The greater flamingo wades in its shallows. Heuglin's bustard 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 many. Closer to the dust is the cushioned gerbil.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 water originating from two separate catchment areas of the Nile. The Lake Turkana drainage basin draws its waters mainly from the 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. 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 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, 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.