The Olkaria Area is a region located to the south of Lake Naivasha in the Great Rift Valley of Kenya, Africa. It is being used to generate clean electric power; the region has an estimated potential of 2,000 MW. This is double the maximum daily electricity peak demand recorded in 2008/2009 for the entire country; the geothermal complex and power plants lie within the Hell's Gate National Park. The Olkaria volcanic area is about 120 kilometres from Nairobi, it lies south of the Ol Doinyo Eburru north of the Suswa volcano. The volcanic field covers 240 square kilometres; the largest structure is Olkaria Hill, 340 metres high. A narrow gorge that crosses the complex with cliffs up to 200 metres high was formed by water flowing out of Lake Naivasha during a period in the past when water levels were much higher than today; the surface at Olkaria is dominated by a peralkaline rhyolite lava field. The complex contains many centers of volcanic activity that erupt in small volumes. There are at least eighty such centers of activity either thick lava flows or steep-sided lava and pyroclastic domes.
Rock from a borehole 1,000 metres deep at Olkaria is around 450,000 years old. But the surface features are no more than 20,000 years old; the oldest exposed sequence is the Ol Njorowa pantellerite formation of pyroclastic rocks, lava flows and plugs. This is thought to be related to a caldera 11 kilometres by 7.5 kilometres that collapsed but is indicated by traces of a ring fracture. The magma has a wide range of compositions representing the different phases after the caldera collapsed. Although dating is not precise, it seems that the older rocks date to 9,000 years before present, while the youngest rocks in the Olobutot formation are between 130 and 230 years old. Olkaria lies within the Naivasha sub-basin, known for hot grounds and fumaroles. Further north, Lake Bogoria has steam jets and geysers with temperatures as high as 96 °C. There are steam fumaroles at Njorowa Gorge in Olkaria. In the underground reservoirs, temperatures of 280 °C have been measured at nearby Eburru and 340 °C at Olkaria.
The geothermal production zones at Olkaria are at depths of between 750 metres to 1,000 metres, further down at between 1,100 metres to 1,300 metres below the surface. Lake Naivasha underground water may be feeding the geothermal reservoir at Olkaria, which has caused concern since the lake has been shrinking in size recently; however the absence of tritium in the steam shows that the water is taking at least fifty years to travel from the lake, if, indeed the source. The first geothermal exploration of Olkaria started in 1955. Two unsuccessful test wells had been drilled by 1959. Little more was done until 1967, when 27 shallow wells up to 61 metres were drilled, some of which emitted steam. Starting in 1970 the Kenya Power Company and the United Nations Development Programme began systematic efforts to survey and exploit the geothermal potential. Production wells were drilled and commercial generation of electricity started in July 1981 with a plant built by Mitsubishi Heavy Industries containing a 15 MW turbo-generator.
A second 15 MW turbine came online in December 1982 and a third in March 1985, bringing total output up to 45 MW of which 3.3MW is used to power the station itself. Thirty production wells had been sunk by 1999 of which twenty-seven were productive, each yielding from 1.5 MW to 8 MW. 15 wells are being used to power the Olkaria I station. Following rising power demands, a third station, Olkaria II was built with a production capacity of 105 MW with 5.2 MW used to power the station itself. It is powered by 3 Mitsubishi turbines each capable of generating 35 MW; the steam is obtained from 22 wells each producing an estimated 35 tonnes of steam per hour. As of 2005 KenGen owned the Olkaria Olkaria II power plants. A third power station with 48 MW capacity, Olkaria III, is owned by a subsidiary of Ormat Technologies; the Olkaria III plant uses air-cooled converters. This new technology has the least impact on the environment of any power generated in Kenya; the project will qualify for carbon credits under the Kyoto Protocol's Clean Development Mechanism.
In February 2010 Ormat announced plans to increase the capacity of their plant to as much as 100 MW. In 2005 KenGen was planning to build a fourth plant. An environmental and social impact assessment was approved by the National Environmental Management Authority, including resettlement of some Maasai communities. In December 2010 the European Investment Bank recommended providing partial financing for a project to expand Olkaria I and build Olkaria IV, adding 280 MW to its capacity. KenGen estimates that the area has a total potential of 2,000 MW. Geothermal power in Kenya Sources
Lake Naivasha is a freshwater lake in Kenya, outside the town of Naivasha in Nakuru County, which lies north west of Nairobi. It is part of the Great Rift Valley; the name derives from the local Maasai name Nai'posha, meaning "rough water" because of the sudden storms which can arise. Lake Naivasha is at the highest elevation of the Kenyan Rift valley at 1,884 metres in a complex geological combination of volcanic rocks and sedimentary deposits from a larger Pleistocene era lake. Apart from transient streams, the lake is fed by the perennial Gilgil rivers. There is no visible outlet, but since the lake water is fresh it is assumed to have an underground outflow; the lake has a surface area of 139 km², is surrounded by a swamp which covers an area of 64 square km, but this can vary depending on rainfall. It is situated at an altitude of 1,884 metres; the lake has an average depth of 6 m, with the deepest area being at Crescent Island, at a maximum depth of 30 m. Njorowa Gorge used to form the lake's outlet, but it is now high above the lake and forms the entrance to Hell's Gate National Park.
The town of Naivasha lies on the north-east edge of the lake. The lake is home to a variety of types of wildlife including over 400 different species of bird and a sizeable population of hippos; the fish community in the lake has been variable over time, influenced by changes in climate, fishing effort and the introduction of invasive species. The most recent shift in the fish population followed the accidental introduction of common carp in 2001. Nine years in 2010, common carp accounted for over 90% of the mass of fish caught in the lake. There are two smaller lakes in the vicinity of Lake Naivasha: Lake Sonachi; the Crater Lake Game Sanctuary lies nearby, while the lake shore is known for its population of European immigrants and settlers. Between 1937 and 1950, the lake was used as a landing place for flying boats on the Imperial Airways passenger and mail route from Southampton in Britain to South Africa, it linked Nairobi. Joy Adamson, the author of Born Free, lived on the shores of the lake in the mid-1960s.
On the shores of the lake is Oserian, which gained notoriety in the Happy Valley days between the two world wars. It now forms part of the Oserian flower farm. In 1999, the Lake Naivasha Riparian Association received the Ramsar Wetland Conservation Award for its conservation efforts regarding the Lake Naivasha Ramsar site. Floriculture forms the main industry around the lake. However, the unregulated use of lake water for irrigation is reducing the level of the lake and is the subject of concern in Kenya. Fishing in the lake is another source of employment and income for the local population; the lake varies in level and dried up in the 1890s. Lake levels in general follow the rainfall pattern in the catchment area. In 1981, the first geothermal plant for Lake Naivasha was commissioned and by 1985, a total of 45 MW of electricity was being generated in the area; the water level for Lake Naivasha reached a low of 0.6 m depth in 1945, but the water level rose again, with minor drops, to reach a maximum depth of nearly 6 m in 1968.
There was another major decline of the water level in 1987, when the depth reached 2.25 m above the lake bottom. The decline of the lake water level in 1987 increased concern in the future of geothermal industry, it was speculated that Lake Naivasha underground water might be feeding the geothermal reservoir at Olkaria. Hence, the decline in the lake water would affect the future of the geothermal industry. Harper, David M.. Lake Naivasha, Kenya. Springer. ISBN 1-4020-1236-5. AFP-TV report about the lake drying up
In hydrology, the inflow of a body of water is the source of the water in the body of water. It can refer to the average volume of incoming water in unit time, it is contrasted with outflow. All bodies of water have multiple inflows, but one inflow may predominate and be the largest source of water. However, in many cases, no single inflow will predominate and there will be multiple primary inflows. For a lake, the inflow may be a river or stream that flows into the lake. Inflow may be speaking, not flows, but rather precipitation, like rain. Inflow can be used to refer to groundwater recharge; the dictionary definition of inflow at Wiktionary
Lake Baringo is, after Lake Turkana, the most northern of the Kenyan Rift Valley lakes, with a surface area of 130 square kilometres and an elevation of 970 metres. The lake is fed by several rivers, Perkerra and Ol Arabel, has no obvious outlet, it is one of the two freshwater lakes in the Rift Valley in the other being Lake Naivasha. In a remote location in a hot and dusty area with over 470 species of birds including migrating flamingos. A Goliath heronry is located on a rocky islet in the lake known as Gibraltar; the lake is part of the East African Rift system. The Tugen Hills, an uplifted fault block of volcanic and metamorphic rocks, lies west of the lake; the Laikipia Escarpment lies to the east. Water flows into the lake from the Mau Hills and Tugen Hills, it is a critical habitat and refuge for more than 500 species of birds and fauna, some of the migratory waterbird species being significant regionally and globally. The lake provides an habitat for seven fresh water fish species. One, Oreochromis niloticus baringoensis, is endemic to the lake.
Lake fishing is important to local economic development. Additionally the area is a habitat for many species of animals including the hippopotamus, Nile crocodile and many other mammals, amphibians and the invertebrate communities. While stocks of Nile tilapia in the lake are now low, the decline of this species has been mirrored by the success of another, the marbled lungfish, introduced to the lake in 1974 and which now provides the majority of fish from the lake. Water levels have been reduced by droughts and over-irrigation; the lake is turbid with sediment due to intense soil erosion in the catchment area on the Loboi Plain south of the lake. The lake has the largest being Ol Kokwe Island. Ol Kokwe, an extinct volcanic centre related to Korosi volcano north of the lake, has several hot springs and fumaroles, some of which have precipitated sulfur deposits. A group of hot springs discharge along the shoreline at Soro near the northeastern corner of the island. Several important archaeological and palaeontological sites, some of which have yielded fossil hominoids and hominins, are present in the Miocene to Pleistocene sedimentary sequences of the Tugen Hills.
The main town near the lake is Marigat, while smaller settlements include Loruk. The area is visited by tourists and is situated at the southern end of a region of Kenya inhabited by pastoralist ethnic groups including Il Chamus, Rendille and Kalenjin. Accommodation, as well as boating services are available at and near Kampi-Ya-Samaki on the western shore, as well as on several of the islands in the lake; the journey to Lake Baringo was famously noted to be "... a genuine pain in the ass" by Jimmy Stewart in a poem read on the Tonight Show with Johnny Carson. Rift Valley lakes Korosi, a volcano at the northern end of Lake Nakuru Media related to Lake Baringo at Wikimedia Commons Chisholm, Hugh, ed.. "Baringo". Encyclopædia Britannica. Cambridge University Press
A lake is an area filled with water, localized in a basin, surrounded by land, apart from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, therefore are distinct from lagoons, are larger and deeper than ponds, though there are no official or scientific definitions. Lakes can be contrasted with rivers or streams, which are flowing. Most lakes streams. Natural lakes are found in mountainous areas, rift zones, areas with ongoing glaciation. Other lakes are found along the courses of mature rivers. In some parts of the world there are many lakes because of chaotic drainage patterns left over from the last Ice Age. All lakes are temporary over geologic time scales, as they will fill in with sediments or spill out of the basin containing them. Many lakes are artificial and are constructed for industrial or agricultural use, for hydro-electric power generation or domestic water supply, or for aesthetic, recreational purposes, or other activities.
The word lake comes from Middle English lake, from Old English lacu, from Proto-Germanic *lakō, from the Proto-Indo-European root *leǵ-. Cognates include Dutch laak, Middle Low German lāke as in: de:Wolfslake, de:Butterlake, German Lache, Icelandic lækur. Related are the English words leak and leach. There is considerable uncertainty about defining the difference between lakes and ponds, no current internationally accepted definition of either term across scientific disciplines or political boundaries exists. For example, limnologists have defined lakes as water bodies which are a larger version of a pond, which can have wave action on the shoreline or where wind-induced turbulence plays a major role in mixing the water column. None of these definitions excludes ponds and all are difficult to measure. For this reason, simple size-based definitions are used to separate ponds and lakes. Definitions for lake range in minimum sizes for a body of water from 2 hectares to 8 hectares. Charles Elton, one of the founders of ecology, regarded lakes as waterbodies of 40 hectares or more.
The term lake is used to describe a feature such as Lake Eyre, a dry basin most of the time but may become filled under seasonal conditions of heavy rainfall. In common usage, many lakes bear names ending with the word pond, a lesser number of names ending with lake are in quasi-technical fact, ponds. One textbook illustrates this point with the following: "In Newfoundland, for example every lake is called a pond, whereas in Wisconsin every pond is called a lake."One hydrology book proposes to define the term "lake" as a body of water with the following five characteristics: it or fills one or several basins connected by straits has the same water level in all parts it does not have regular intrusion of seawater a considerable portion of the sediment suspended in the water is captured by the basins the area measured at the mean water level exceeds an arbitrarily chosen threshold With the exception of the seawater intrusion criterion, the others have been accepted or elaborated upon by other hydrology publications.
The majority of lakes on Earth are freshwater, most lie in the Northern Hemisphere at higher latitudes. Canada, with a deranged drainage system has an estimated 31,752 lakes larger than 3 square kilometres and an unknown total number of lakes, but is estimated to be at least 2 million. Finland has larger, of which 56,000 are large. Most lakes have at least one natural outflow in the form of a river or stream, which maintain a lake's average level by allowing the drainage of excess water; some lakes do not have a natural outflow and lose water by evaporation or underground seepage or both. They are termed endorheic lakes. Many lakes are artificial and are constructed for hydro-electric power generation, aesthetic purposes, recreational purposes, industrial use, agricultural use or domestic water supply. Evidence of extraterrestrial lakes exists. Globally, lakes are outnumbered by ponds: of an estimated 304 million standing water bodies worldwide, 91% are 1 hectare or less in area. Small lakes are much more numerous than large lakes: in terms of area, one-third of the world's standing water is represented by lakes and ponds of 10 hectares or less.
However, large lakes account for much of the area of standing water with 122 large lakes of 1,000 square kilometres or more representing about 29% of the total global area of standing inland water. Hutchinson in 1957 published a monograph, regarded as a landmark discussion and classification of all major lake types, their origin, morphometric characteristics, distribution; as summarized and discussed by these researchers, Hutchinson presented in it a comprehensive analysis of the origin of lakes and proposed what is a accepted classification of lakes according to their origin. This
Lake Magadi is the southernmost lake in the Kenyan Rift Valley, lying in a catchment of faulted volcanic rocks, north of Tanzania's Lake Natron. During the dry season, it is 80% covered by soda and is well known for its wading birds, including flamingos. Lake Magadi is a saline, alkaline lake 100 square kilometers in size, that lies in an endorheic basin formed by a graben; the lake is an example of a "saline pan". The lake water, a dense sodium carbonate brine, precipitates vast quantities of the mineral trona. In places, the salt is up to 40 m thick; the lake is recharged by saline hot springs that discharge into alkaline "lagoons" around the lake margins, there being little surface runoff in this arid region. Most hot springs lie along southern shorelines of the lake. During the rainy season, a thin layer of brine covers much of the saline pan, but this evaporates leaving a vast expanse of white salt that cracks to produce large polygons. A single species of fish, a cichlid Alcolapia grahami, inhabits the hot alkaline waters of this lake basin and is seen in some of the hot spring pools around the shoreline, where the water temperature is less than 45 °C.
Lake Magadi was not always so saline. Several thousand years ago, the Magadi basin held a freshwater lake with many fish, whose remains are preserved in the High Magadi Beds, a series of lacustrine and volcaniclastic sediments preserved in various locations around the present shoreline. Evidence exists for several older Pleistocene precursor lakes that were much larger than present Lake Magadi. At times, Lake Magadi and Lake Natron were united as a single larger lake. Lake Magadi is well known for its extensive deposits of siliceous chert. There are many varieties including bedded cherts that formed in the lake and intrusive dike-like bodies that penetrated through overlying sediments while the silica was soft. Most famous is "Magadi-type chert", which formed from a sodium silicate mineral precursor magadiite, discovered at Lake Magadi in 1967. Magadi township lies on the lake's east shore, is home to the Magadi Soda factory, owned by Tata India since December 2005; this factory produces soda ash.
The lake is featured in Fernando Meirelles's film The Constant Gardener, based on the book of the same name by John le Carré, although in the film the shots are supposed to be at Lake Turkana. A causeway that crosses the lake provides access to the area west of the lake. Accommodation for tourists is provided in air conditioned canvas tents. Ngorongoro Conservation Area has a Lake Magadi. Baker, B. H. 1958. Geology of the Magadi area. Report of the Geological Survey of Kenya, 42, 81 pp. Behr, H. J. 2002. Magadiite and Magadi chert: a critical analysis of the silica sediments in the Lake Magadi Basin, Kenya. SEPM Special Publication 73, p. 257-273. Eugster, H. P. 1970. Chemistry and origin of the brines from Lake Magadi, Kenya. Mineralogical Society of America Special Paper, No. 3, p. 215-235. Eugster, H. P. 1980. Lake Magadi and its Pleistocene precursors. In Nissenbaum, A. Hypersaline evaporitic environments. Elsevier, Amsterdam, pp. 195–232. Jones, B. F. Eugster, H. P. and Rettig, S. L. 1977. Hydrochemistry of the Lake Magadi basin, Kenya.
Geochimica et Cosmochimica Acta, v. 41, p. 53-72. Slide show of aerial photos by Christophe Gruault at Fotopedia
Lake Victoria is one of the African Great Lakes. The lake was named after Queen Victoria by the explorer John Hanning Speke, the first Briton to document it. Speke accomplished this in 1858, while on an expedition with Richard Francis Burton to locate the source of the Nile River. With a surface area of 59,947 square kilometres, Lake Victoria is Africa's largest lake by area, the world's largest tropical lake, the world's second largest fresh water lake by surface area after Lake Superior in North America. In terms of volume, Lake Victoria is the world's ninth largest continental lake, containing about 2,424 cubic kilometres of water. Lake Victoria occupies a shallow depression in Africa; the lake has an average depth of 40 metres. Its catchment area covers 169,858 square kilometres; the lake has a shoreline of 7,142 kilometres when digitized at the 1:25,000 level, with islands constituting 3.7 percent of this length, is divided among three countries: Kenya and Tanzania. Geologically, Lake Victoria is young at about 400,000 years old.
It formed. During its geological history, Lake Victoria went through changes ranging from its present shallow depression, through to what may have been a series of much smaller lakes. Geological cores taken from its bottom show Lake Victoria has dried up at least three times since it formed; these drying cycles are related to past ice ages, which were times when precipitation declined globally. Lake Victoria last dried out about 17,300 years ago, it refilled 14,700 years ago as the African humid period began. Lake Victoria receives 80 percent of its water from direct rainfall. Average evaporation on the lake is between 2.0 and 2.2 metres per year double the precipitation of riparian areas. Lake Victoria receives its water additionally from rivers, thousands of small streams; the Kagera River is the largest river flowing into this lake, with its mouth on the lake's western shore. Lake Victoria is drained by the Nile River near Jinja, Uganda, on the lake's northern shore. In the Kenya sector, the main influent rivers are the Sio, Yala, Sondu Miriu and Migori.
The only outflow from Lake Victoria is the Nile River, which exits the lake near Uganda. In terms of contributed water, this makes Lake Victoria the principal source of the longest branch of the Nile. However, the most distal source of the Nile Basin, therefore the ultimate source of the Nile, is more considered to be one of the tributary rivers of the Kagera River, which originates in either Rwanda or Burundi; the uppermost section of the Nile is known as the Victoria Nile until it reaches Lake Albert. Although it is a part of the same river system known as the White Nile and is referred to as such speaking this name does not apply until after the river crosses the Uganda border into South Sudan to the north; the lake exhibits eutrophic conditions. In 1990–1991, oxygen concentrations in the mixed layer were higher than in 1960–1961, with nearly continuous oxygen supersaturation in surface waters. Oxygen concentrations in hypolimnetic waters were lower in 1990–1991 for a longer period than in 1960–1961, with values of less than 1 mg per litre occurring in water as shallow as 40 metres compared with a shallowest occurrence of greater than 50 metres in 1961.
The changes in oxygenation are considered consistent with measurements of higher algal biomass and productivity. These changes have arisen for multiple reasons: successive burning within its basin and ash from, deposited over the lake's wide area; the lake is considered a shallow lake considering its large geographic area with a maximum depth of 80 metres and an average depth of 40 metres. A 2016 project created the first true bathymetric map of the lake; the deepest part of the lake is offset to the east of the lake near Kenya and the lake is shallower in the west along the Ugandan shoreline and the south along the Tanzanian shoreline. Many mammal species live in the region of Lake Victoria, some of these are associated with the lake itself and the nearby wetlands. Among these are the hippopotamus, African clawless otter, spotted-necked otter, marsh mongoose, bohor reedbuck, defassa waterbuck, cane rats, giant otter shrew. Lake Victoria and its wetlands has a large population of Nile crocodiles, as well as African helmeted turtles, variable mud turtles, Williams' mud turtle.
The Williams' mud turtle is restricted to Lake Victoria and other lakes and swamps in the upper Nile basin. Lake Victoria was rich in fish, including many endemics, but a high percentage of these became extinct during the last 50 years; the main group in Lake Victoria is the haplochromine cichlids with more than 500 species all endemic and some still undescribed. This is far more species of fish except Lake Malawi. These