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72-712: In 2002 rubies were found in the region of the Waseges River. The river flows north, then west and south to enter Lake Bogoria in the Great Rift Valley from the north after passing through the Kesubo swamp. In its upper reaches, the Waseges flows through regions of intensive coffee cultivation where heavy use is made of chemical fertilizers and pesticides. Lower down it flows through bush and scrub used for grazing, and then through very dry bush before entering

144-427: A hierarchical pattern . Other terms for a drainage basin are catchment area , catchment basin , drainage area , river basin , water basin , and impluvium . In North America, they are commonly called a watershed , though in other English-speaking places, "watershed" is used only in its original sense, that of the drainage divide line. A drainage basin's boundaries are determined by watershed delineation ,

216-437: A common task in environmental engineering and science. In a closed drainage basin, or endorheic basin , rather than flowing to the ocean, water converges toward the interior of the basin, known as a sink , which may be a permanent lake, a dry lake , or a point where surface water is lost underground . Drainage basins are similar but not identical to hydrologic units , which are drainage areas delineated so as to nest into

288-400: A consequence of faulting. In 1969, it spread over 6 km in length; but water was diverted from the Waseges river and by 2001 it was only 3.5 km long and about 0.5 km wide. At least three warm springs, and groundwater inputs, feed it. The Loboi river also contributes to it but that river periodically shifts its bed ( avulsions ) and that modifies its relative role regarding the swamp. This river

360-450: A denser more saline bottom waters. The lake has not always been saline. Sediment cores from the lake floor have shown that freshwater conditions existed for several periods during the past 10,000 years. Of the ca. 60 hot springs that discharge on Loburu delta plain on the western margin of the lake, travertine appears at 20% of them. Carbonate is actively precipitating at several of these, as shown by calcite-encrusted artefacts. This

432-454: A drainage basin, and there are different ways to interpret that data. In the unlikely event that the gauges are many and evenly distributed over an area of uniform precipitation, using the arithmetic mean method will give good results. In the Thiessen polygon method, the drainage basin is divided into polygons with the rain gauge in the middle of each polygon assumed to be representative for

504-540: A drainage boundary is referred to as watershed delineation . Finding the area and extent of a drainage basin is an important step in many areas of science and engineering. Most of the water that discharges from the basin outlet originated as precipitation falling on the basin. A portion of the water that enters the groundwater system beneath the drainage basin may flow towards the outlet of another drainage basin because groundwater flow directions do not always match those of their overlying drainage network. Measurement of

576-465: A drainage divide that separates lake Bogoria and lake Baringo. The faults control over 200 hot and cold springs and seeps, which bring a significant water input. Core analysis of the lake floor has revealed two types of sedimentation: a shallow fan–deltaic clastic zone; and a deeper zone where Organic matters alternate with evaporites . The organic muds were formed during periods of relatively high lake level and high microbial productivity; whereas

648-585: A landmark ruling, ordering the Kenyan government to restore the Endorois to their historic land, compensate them from losses and sharing with them the profits from the Lake Bogoria game reserve. But in 2022, Minority Rights Group reported that that decision had not yet been implemented and has many Endorois were still consigned to 'severe poverty, illiteracy, poor health and a life of destitution.' In 2024

720-572: A less flexible system, created tensions between the Tugen and Camus people, and tensions among the Tugen. Before 2003 the river was illegally diverted for irrigation upstream in the Subukia area, causing it to dry up downstream during a period of drought. In 2003 the Ministry of Water Management and Development proposed to establish river basin catchment committees and water user associations to manage

792-528: A major fault, with steep slopes that prevent wetland development (the Siracho Escarpment, to the east ). To the west, trachy phonolites (uncommon extrusive igneous rock) are cut through by numerous gently sloping tilt-blocks; rivers oriented north-south feed delta lobes, where spring-fed wetlands have developed. The north opens on a basin with Quaternary silts , sands and gravels; there, the gently sloping Sandai and Loboi plains gradually rise to

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864-602: A multi-level hierarchical drainage system . Hydrologic units are defined to allow multiple inlets, outlets, or sinks. In a strict sense, all drainage basins are hydrologic units but not all hydrologic units are drainage basins. About 48.71% of the world's land drains to the Atlantic Ocean . In North America , surface water drains to the Atlantic via the Saint Lawrence River and Great Lakes basins,

936-467: A pH range of 9.3–10.6. Some shallow marginal lagoons have salinities exceeding 100 g l−1. Temperature at the time of sampling ranged between 28 and 33 ◦C, but exceed 60 ◦C at sublacustrine hot spring vents. However, cyanobacteria — mainly Spirulina platensis — are abundant and support up to 2 million flamingoes. Lake Bogoria is in a geothermally active part of the Kenya Rift Valley, and

1008-566: A variety of fluvial, deltaic, and beach settings. It has active hot springs that feed a series of marshes dominated by Cyperus laevigatus . The springs are alkaline, of the Na-HCO 3 type, contain a lot of silica and nitrate, and the temperature near the vents is extremely hot (more than 96◦C). The areas immediately adjacent to the vents and in nearby streamlets commonly include microbial mats of Phormidium, Pseudanabaena , Spirulina , Synechococcus and Calothrix , but are devoid of macrophytes.

1080-632: A wetter area populated by near pure stands of Cyperus papyrus that are rooted or floating in water up to 1.5 m deep. Acacia scrub occurs on an adjacent horst block to the west, with grasses such as Sporobolus spicata on adjacent plains. These are also to the north of the lake, east of the Loboi swamp. They rest at the southern end of an extensive alluvial fan formed by the Sandai river. The Kesubo Floodplain Marshes are seasonally flooded and lie between

1152-509: Is above 2500 mm, thus inducing a water deficit and creating semi-arid conditions over most of the lower parts of the Bogoria basin. Although the lake is in a semi-arid part of Kenya Rift Valley , it is surrounded by numerous and varied wetlands along its shorelines, along faults where hot, warm and cold springs have developed, and along rivers that run across the rift floor. Six major types of wetland have been defined around lake Bogoria:

1224-555: Is cool and only slightly alkaline. The springs have a similar chemistry but they are warmer, have a higher nitrate content, and are slightly acidic. The resulting waters of the Loboi Swamp are also slightly alkaline, and generally reflect the mixing of fluvial, spring and groundwater inflows. Its areas of semi-permanent or seasonal standing water are dominated by Typha domingensis and also have some Leersia hexandra , Ipomoea aquatica , and other taxa . These areas surround

1296-531: Is famous for geysers and hot springs along the bank of the lake and in the lake. There are about 200 hot springs, most of which are distributed along the shoreline. In four locations around the lake can be observed at least 10 geysers, which erupt up to 5 m high. Geyser activity is affected by the fluctuations of lake level, which may inundate or expose some geysers. Lake Bogoria occupies an asymmetric basin approximately 20 km long and 10 km wide, bordered by faults . The east and south borders are marked by

1368-430: Is generally 3,300 ha (8,200 acres) but this fluctuates, essentially according to the amount of rainfall. Most of the rain falls between April and November, and precipitation ranges average about 700 mm on the Loboi plain and 1200 mm on the adjacent highlands. But El Nino years bring increased rainfall and flooding of the lake shores. For example, in 2020 its area increased to about 4,690 ha (11,600 acres): 2020

1440-487: Is referred to as " watershed management ". In Brazil , the National Policy of Water Resources, regulated by Act n° 9.433 of 1997, establishes the drainage basin as the territorial division of Brazilian water management. When a river basin crosses at least one political border, either a border within a nation or an international boundary, it is identified as a transboundary river . Management of such basins becomes

1512-614: Is the Dead Sea . Drainage basins have been historically important for determining territorial boundaries, particularly in regions where trade by water has been important. For example, the English crown gave the Hudson's Bay Company a monopoly on the fur trade in the entire Hudson Bay basin, an area called Rupert's Land . Bioregional political organization today includes agreements of states (e.g., international treaties and, within

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1584-472: Is unusual, in that this precipitation most probably occurs at temperatures over 80 °C. The geysers are believed by some to have medicinal value. The terrestrial vegetation that immediately surrounds the lake is mainly a thorny bushland dominated by Acacia , Salvadora , Balanites and Commiphora species. There are also patches of riverine woodland with Ficus capensis , Acacia xanthophloea and Acacia tortilis . One species dominates

1656-469: The Brachionus plicatilis cryptic species complex) is found in high densities. A new alkaliphilic purple nonsulfur bacterium was discovered in lake Bogoria; it has been named Rhodobaca bogoriensis . The lake supports more than 300 waterbird species. It is an important stopover site for a population of up to 1.5 million migratory birds, notably for the lesser flamingo ( Phoeniconaias minor ). In

1728-713: The African Great Lakes , the interiors of Australia and the Arabian Peninsula , and parts in Mexico and the Andes . Some of these, such as the Great Basin, are not single drainage basins but collections of separate, adjacent closed basins. In endorheic bodies of water where evaporation is the primary means of water loss, the water is typically more saline than the oceans. An extreme example of this

1800-529: The Baringo District Provincial Irrigation Unit (PIU), funded and given technical support by Dutch Aid, aimed to improve the usage of the river waters. The planned irrigation scheme was based on a single large concrete-lined canal feeding just one area. Scheduled for launch in 1983, there were delays due to protests from the local people, and the project was not completed until the 1987/1988 season. The project introduced

1872-607: The Eastern Seaboard of the United States, the Canadian Maritimes , and most of Newfoundland and Labrador . Nearly all of South America east of the Andes also drains to the Atlantic, as does most of Western and Central Europe and the greatest portion of western Sub-Saharan Africa , as well as Western Sahara and part of Morocco . The two major mediterranean seas of the world also flow to

1944-735: The Mississippi (3.22 million km ), and the Río de la Plata (3.17 million km ). The three rivers that drain the most water, from most to least, are the Amazon, Ganges , and Congo rivers. Endorheic basin are inland basins that do not drain to an ocean. Endorheic basins cover around 18% of the Earth's land. Some endorheic basins drain to an Endorheic lake or Inland sea . Many of these lakes are ephemeral or vary dramatically in size depending on climate and inflow. If water evaporates or infiltrates into

2016-809: The Nile River ), Southern , Central, and Eastern Europe , Turkey , and the coastal areas of Israel , Lebanon , and Syria . The Arctic Ocean drains most of Western Canada and Northern Canada east of the Continental Divide , northern Alaska and parts of North Dakota , South Dakota , Minnesota , and Montana in the United States, the north shore of the Scandinavian peninsula in Europe, central and northern Russia, and parts of Kazakhstan and Mongolia in Asia , which totals to about 17% of

2088-568: The Sandai and Emsos rivers, and from about 200 alkaline hot springs that are present at three onshore sites: Loburu, Chemurkeu, and a southern group (Ng'wasis, Koibobei, Losaramat). Other springs discharge directly from the lake floor. Lake Bogoria also contains the highest concentration of true geysers in Africa (at least 18 have been active in the 35 years before 2008). The lake is meromictic (stratified) with less dense surface waters lying on

2160-551: The Waseges river (or Sandai river), the latter bringing a small permanent flow of the diverted Loboi river. These wetlands are fed by ephemeral or perennial streams, and by springs. In the south, two freshwater springs supply permanent streams. All three (the Wasenge river and the two streams) are used extrensively for drinking, as well as the water from some hot springs streams — some of these being substantially less salty than

2232-966: The phytoplankton : Arthrospira fusiformis , a cyanobacterium spirulina . But all these wetlands see the occurrence of diatoms in at least parts of them; these diatoms vary in diversity, abundance and species composition. The main factors directing these variables are pH, temperature, and specific conductivity; secondary factors are Si and nitrate . Hot springs generally have a low diversity of diatoms, with variable abundance; they commonly include Anomoeoneis sphaerophora var. guntheri , Navicula tenella , Navicula cuspidata , and Nitzschia invisitata . In other wetland types, distinctive diatom floras variously include Fragilaria brevistriata , Gomphonema parvulum , Navicula tenelloides , Nitzschia communis , N. latens , N. sigma , Rhopalodia gibberula , and Stauroneis anceps . The flamingoes feed on Arthrospira fusiformis . The monogonont rotifer species Brachionus sp. Austria (belonging to

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2304-547: The 1990s, two episodes of mass deaths occurred among flamingos, all starting from Lake Bogoria. The first episode, in 1993-1995, saw about 35,000 flamingos dying between August and November 1993 and about 15,000 dying in August 1995. The second episode occurred in 1999-2000; the number of deaths for 2000 was estimated at around 100,000. In both cases, flamingos were the only water bird species falling victim to this unknown phenomenon. The studies on these events were not conclusive as to

2376-789: The Andes. The Indian Ocean 's drainage basin also comprises about 13% of Earth's land. It drains the eastern coast of Africa, the coasts of the Red Sea and the Persian Gulf , the Indian subcontinent , Burma, and most parts of Australia . The five largest river basins (by area), from largest to smallest, are those of the Amazon (7 million km ), the Congo (4 million km ), the Nile (3.4 million km ),

2448-726: The Atlantic. The Caribbean Sea and Gulf of Mexico basin includes most of the U.S. interior between the Appalachian and Rocky Mountains , a small part of the Canadian provinces of Alberta and Saskatchewan , eastern Central America , the islands of the Caribbean and the Gulf, and a small part of northern South America. The Mediterranean Sea basin, with the Black Sea , includes much of North Africa , east-central Africa (through

2520-463: The Cyperus marshes, which have similar water chemistries, are dominated by short reeds less than 20 cm high. Temperatures range from about 32◦C to about 60◦C near the hot spring streamlets that cross the marshes. There are also algal and cyanobacterial mats. The lake shoreline at Loburu (and other shorelines) does not present many aquatic macrophytes. The lake brine is of Na-CO3-HCO3-Cl composition, with

2592-703: The Endorois allied with the Ogiek people — who have themselves been initially evicted in 1920 from their ancestral grounds in the Mau Forest (south-west Kenya) by the British colonial government. In 2017 the Ogiek also won a court case against the Kenian government, whereby the latter was supposed to restitute the Ogiek ancestral land and pay a compensation of 157,000 Kenyan shillings ($ 1,026) per person. As of 2024, not only

2664-623: The US, interstate compacts ) or other political entities in a particular drainage basin to manage the body or bodies of water into which it drains. Examples of such interstate compacts are the Great Lakes Commission and the Tahoe Regional Planning Agency . In hydrology , the drainage basin is a logical unit of focus for studying the movement of water within the hydrological cycle . The process of finding

2736-406: The basin, it can form tributaries that change the structure of the land. There are three different main types, which are affected by the rocks and ground underneath. Rock that is quick to erode forms dendritic patterns, and these are seen most often. The two other types of patterns that form are trellis patterns and rectangular patterns. Rain gauge data is used to measure total precipitation over

2808-470: The common hippopotamus ( Hippopotamus amphibius ) and African lion ( Panthera leo ); another important species is the greater kudu ( Tragelaphus strepsiceros ). The lake's stable water level makes it doubly important during periods of drought, when water levels in other East African lakes drop. The Site is a UNESCO World Heritage Site since 2011 and an Important Bird and Biodiversity Area (IBA). The Ramsar site, designated on August 27, 2001, covers

2880-430: The discharge of water from a basin may be made by a stream gauge located at the basin's outlet. Depending on the conditions of the drainage basin, as rainfall occurs some of it seeps directly into the ground. This water will either remain underground, slowly making its way downhill and eventually reaching the basin, or it will permeate deeper into the soil and consolidate into groundwater aquifers. As water flows through

2952-441: The drainage area is dependent on the soil type. Certain soil types such as sandy soils are very free-draining, and rainfall on sandy soil is likely to be absorbed by the ground. However, soils containing clay can be almost impermeable and therefore rainfall on clay soils will run off and contribute to flood volumes. After prolonged rainfall even free-draining soils can become saturated , meaning that any further rainfall will reach

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3024-697: The drainage basin to the mouth, and may accumulate there, disturbing the natural mineral balance. This can cause eutrophication where plant growth is accelerated by the additional material. Because drainage basins are coherent entities in a hydrological sense, it has become common to manage water resources on the basis of individual basins. In the U.S. state of Minnesota , governmental entities that perform this function are called " watershed districts ". In New Zealand, they are called catchment boards. Comparable community groups based in Ontario, Canada, are called conservation authorities . In North America, this function

3096-568: The entire National Reserve, with an area of 10,700 ha (26,000 acres), shared between the 3,300 ha lake and 7,400 ha of riparian and terrestrial habitats. The lake area was the traditional home of the Endorois people , who were forced to leave the area in the 1970s and are now challenging their removal at the African Commission on Human and Peoples' Rights . In 2009 the African Commission on Human and Peoples' Rights (ACHPR) made

3168-706: The evaporites were formed during drier periods. The cores attest of many environmental fluctuations during the past 30 000 years, linked to regional climatic changes and to local tectonic and hydrological conditions. Lake Bogoria is a soda lake : it has no surface outlet, its waters are strongly alkaline ( pH :10.5). High salt concentrations are also given (40‰) and this increases when the total amount of water decreases (evapoconcentration). Thus, following an extreme draught from March to October 2009, salt saturation reached 48‰. Soda lakes are highly productive ecosystems. Its waters contain large concentrations of Na , HCO 3 , CO 3 et Cl ions. They originate from inflow from

3240-588: The government has so far failed to implement the court's orders as in the case of the Endorois, but has persisted in further evictions imposed in November 2023 by the Kenyan authorities during the visit of Britain's King Charles III . On 6 February 2024, both ethnies demonstrated together in Nairobi with the support of the International Network for Economic, social and cultural rights to demand

3312-404: The government implement the rulings. The area is inhabited by Tugen and Jemps pastoralists, and livestock grazing is the main land use in the area. The lake and its surroundings attract 200,000 tourists per year, due to the wildlife, the hot springs, the spectacular cliffs and escarpments and the rich indigenous culture. Hotel accommodation is available near Loboi village at the north end of

3384-443: The graminoid vegetation is interspersed with cyanobacterial and algal mats. Water from the blister mounds, and other seeps and springs, support wet meadows and Typha swamps. The blister mounds and Typha swamps have a more or less neutral pH, low conductivities and total alkalinity. The marshes to the north of the lake do not feed any river outlet. They are linked to both Lake Bogoria and adjacent Lake Baringo ; both lakes are fed by

3456-435: The ground and along rivers it can pick up nutrients , sediment , and pollutants . With the water, they are transported towards the outlet of the basin, and can affect the ecological processes along the way as well as in the receiving water body . Modern use of artificial fertilizers , containing nitrogen (as nitrates ), phosphorus , and potassium , has affected the mouths of drainage basins. The minerals are carried by

3528-781: The ground at its terminus, the area can go by several names, such playa, salt flat, dry lake , or alkali sink . The largest endorheic basins are in Central Asia , including the Caspian Sea , the Aral Sea , and numerous smaller lakes. Other endorheic regions include the Great Basin in the United States, much of the Sahara Desert , the drainage basin of the Okavango River ( Kalahari Basin ), highlands near

3600-532: The lake at its northern end. The river is seasonal, and is the main affluent of the lake. The inertial flow of the river may generate counter-clockwise currents in the lake. Its water pH is 8, a mild alcaline level. The Waseges is an important source of irrigation water. With rising populations, by 1985 the Tugen people of Sandai were sometimes refusing to allow their neighbors, the Camus people , to use water from

3672-521: The lake water. Other streams, such as the Emsos to the south and the Parkirichai to the west, are ephemeral: they flow only after heavy rains. This swamp is to the north of the lake. It hugs the base of a horst block (raised fault block bounded by normal faults) oriented north-south. According to radiocarbon datation, it was created only 700 years ago in a former floodplain environment — possibly as

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3744-484: The lake's level fluctuates seasonally by 50 to 100 cm; and that it can vary by several meters for short periods, having fluctuated between c. 988 and c. 996 m during the 20th century. Lake-shore terraces around the shoreline, made of coarse angular gravel and angular orthoconglomerates, mark higher lake levels from the Pleistocene and Holocene. They are visible on 45% of the present level, and some are about 9 m above

3816-528: The lake. Camping is permitted at the southern end of the lake. Drainage basin A drainage basin is an area of land in which all flowing surface water converges to a single point, such as a river mouth , or flows into another body of water , such as a lake or ocean . A basin is separated from adjacent basins by a perimeter, the drainage divide , made up of a succession of elevated features, such as ridges and hills . A basin may consist of smaller basins that merge at river confluences , forming

3888-445: The main cause of death. Heavy metal poisoning was suggested but such poisoning does not have a periodic effect: its effect are continuous, and in these cases not compatible with the periodic dying; nor was it coherent with that birds of all ages were concerned, whereas such poisoning affects older individuals more than younger ones (ther older ones have had more time to accumulate poison in their bodies). Food poisoning has also been cited.

3960-445: The main food for lesser flamingo is Spirulina platensis , which is abundantly produced in the lakes of that region; but around the years that saw this heavy mortality toll, there had been an important increase of toxic cyanobacteria , especially during periods of algal blooms ; and the symptoms of dying flamingos were similar to those of algal toxicity. Its immediate surroundings are a critical habitat for vulnerable species such as

4032-454: The other endorheic lakes in Kenya. The Rift Valley lakes undergo regular (and cyclic) changes in water levels mostly in response to precipitation, which is unreliable and unpredictable. In this region, lake Bogoria is the only alkaline lake that has minimal lake water fluctuations, and is used as a refuge for flamigos and other animals when other relatively shallow lakes dry out. Its surface

4104-446: The present shoreline. In 1991 the maximum length is 17.6 km (10.9 mi) and its width ranges from 0.5 km (0.31 mi) to 3.6 km (2.2 mi). The drainage basin is 700 km (270 sq mi) . The lowest point of the drainage divide is at 999 m near Loboi village; when the level of the lake reaches that altitude, its waters flow northward in lake Baringo drainage basin . In 1978 its maximum depth

4176-418: The rainfall on the area of land included in its polygon. These polygons are made by drawing lines between gauges, then making perpendicular bisectors of those lines form the polygons. The isohyetal method involves contours of equal precipitation are drawn over the gauges on a map. Calculating the area between these curves and adding up the volume of water is time-consuming. Isochrone maps can be used to show

4248-631: The responsibility of the countries sharing it. Nile Basin Initiative , OMVS for Senegal River , Mekong River Commission are a few examples of arrangements involving management of shared river basins. Management of shared drainage basins is also seen as a way to build lasting peaceful relationships among countries. The catchment is the most significant factor determining the amount or likelihood of flooding . Catchment factors are: topography , shape, size, soil type, and land use (paved or roofed areas). Catchment topography and shape determine

4320-508: The rift valley boundary faults, to the east, and a small horst block, to the west. The river waters are slightly alkaline, cool, and have a low total alkalinity. The marshes are similar in their general water chemistry, but are slightly acidic and have a distinctly lower NO3 content. Short grasses are the dominant vegetation type and cattle graze the area. These lie near the Lake Bogoria National Reserve entrance, to

4392-461: The river rather than being absorbed by the ground. If the surface is impermeable the precipitation will create surface run-off which will lead to higher risk of flooding; if the ground is permeable, the precipitation will infiltrate the soil. Land use can contribute to the volume of water reaching the river, in a similar way to clay soils. For example, rainfall on roofs, pavements , and roads will be collected by rivers with almost no absorption into

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4464-436: The river. The Sandai farmers had been in the habit of cultivating two or three out of six cultivated areas each year. A given area would be farmed for three or four years, then left fallow for up to four years. All the areas are fed by canals from the Waseges, but half the canals will be blocked at any time. Use of the irrigated farm areas involved agreements between the Tugen and Camus people. An irrigation scheme carried out by

4536-432: The south of the Loboi swamp, and at the limit dividing faulted volcanic uplands and colluvial-alluvial sediments. They contain several types of habitats. Ashley et al. 2002 defined them as an 'Artesian Blister Wetland' (see Types of wetlands above), and that wetland also includes slightly acidic, nitrate enriched, warm springs. This is on the western shore of Lake Bogoria. It is composed of silts and gravels, and shows

4608-418: The speed with which the runoff reaches a river. A long thin catchment will take longer to drain than a circular catchment. Size will help determine the amount of water reaching the river, as the larger the catchment the greater the potential for flooding. It is also determined on the basis of length and width of the drainage basin. Soil type will help determine how much water reaches the river. The runoff from

4680-415: The time taken for rain to reach the river, while catchment size, soil type, and development determine the amount of water to reach the river. Generally, topography plays a big part in how fast runoff will reach a river. Rain that falls in steep mountainous areas will reach the primary river in the drainage basin faster than flat or lightly sloping areas (e.g., > 1% gradient). Shape will contribute to

4752-477: The time taken for runoff water within a drainage basin to reach a lake, reservoir or outlet, assuming constant and uniform effective rainfall. Drainage basins are the principal hydrologic unit considered in fluvial geomorphology . A drainage basin is the source for water and sediment that moves from higher elevation through the river system to lower elevations as they reshape the channel forms. Drainage basins are important in ecology . As water flows over

4824-476: The use of the river. Lake Bogoria Lake Bogoria (formerly Lake Hannington) is a saline , alkaline lake that lies in a volcanic region in a half- graben basin south of Lake Baringo , Kenya , a little north of the equator . Lake Bogoria, like Lake Nakuru , Lake Elementeita , and Lake Magadi further south in the Rift Valley , and Lake Logipi to the north, is periodically home to one of

4896-789: The world's land. Just over 13% of the land in the world drains to the Pacific Ocean . Its basin includes much of China, eastern and southeastern Russia, Japan, the Korean Peninsula , most of Indochina, Indonesia and Malaysia, the Philippines, all of the Pacific Islands , the northeast coast of Australia , and Canada and the United States west of the Continental Divide (including most of Alaska), as well as western Central America and South America west of

4968-560: The world's largest populations of lesser flamingos . The lake is a Ramsar site and Lake Bogoria National Reserve has been a protected National Reserve since November 29, 1973. The lake was formerly named after Bishop James Hannington who visited in 1885. Lake Bogoria is located in Baringo County, about 120 km north of Nakuru city and 240 km north of Nairobi . It is in the Gregorian Rift Valley . It

5040-592: Was once part of a larger freshwater lake, joined with the current Lake Baringo . As shown on the satellite picture at the top of this page, it is divided in three lobes: a large center one and two smaller ones at the north and south extremities. The two narrower areas separating these lobes are shallow, tectonically controlled sills at Nyalibuch and Mwanassis. There are contradictions regarding its altitude. Unesco's Ramsar gives 963 m (3,159 ft). More precise — and more prudent —, Renaut & Owen 1991 give c. 990 m as of August 1977, but also indicate that

5112-419: Was one of the hottest years on record, but despite depressed rainfall in the short-rains season (October to December, or OND) it also saw a wetter than normal January and February because of the strong positive Indian Ocean Dipole index during that period, and enhanced rainfall during the long-rains season (March to May, or MAM) (that year, Lake Victoria rose to a new record level). However, evaporation rate

5184-475: Was recorded as 12 m (39 ft) or 11.5 m (38 ft), and Renaut & Owen 1991 precise that this was in the largest sub-basin or lobe; and that the two smaller parts at the north and south extremities were 5.5 m (18 ft) deep at that time. In 2003 its maximum depth is just over 10 m (33 ft) in an area of 3,000 ha (7,400 acres). This is relatively shallow, but nevertheless deeper — and therefore hydrologically more stable — than

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