{{Infobox river , name = Yala River , image = YalaRiver.JPG , image_size = , image_caption = Yala river within Kakamega rainforest, western Kenya , image_alt = , map = , map_size = , map_caption = , map_alt = , pushpin_map = Kenya , pushpin_map_size = , pushpin_map_caption= Mouth location , pushpin_map_alt = , subdivision_type1 = Country , subdivision_name1 =

Kenya ) , national_anthem = "Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi , ...

, subdivision_type2 = , subdivision_name2 = , subdivision_type3 = , subdivision_name3 = , subdivision_type4 = , subdivision_name4 = , subdivision_type5 = , subdivision_name5 = , length = {{convert, 219, km , width_min = , width_avg = , width_max = , depth_min = , depth_avg = , depth_max = , discharge1_location= , discharge1_min = , discharge1_avg = , discharge1_max = , source1 = , source1_location = , source1_coordinates= , source1_elevation = , mouth =

Lake Victoria Lake Victoria is one of the African Great Lakes. With a surface area of approximately , Lake Victoria is Africa's largest lake by area, the world's largest tropical lake, and the world's second-largest fresh water lake by surface area after ...

, mouth_location = , mouth_coordinates = {{Coord, -0.060998 , 34.042633, display=inline,title , mouth_elevation = , progression = , river_system = , basin_size = {{convert, 3351, km2 , basin_landmarks = , basin_population = , tributaries_left = , tributaries_right = , waterbodies = , waterfalls = , bridges = , ports = , custom_label = , custom_data = , extra = The Yala River is a river of western Kenya, a tributary of

. It generally flows fast over a rocky bed through a wide valley before joining the

Nzoia River The Nzoia River is a Kenyan river, rising from Cherangany hills. It passes through Kapsara, Springer ,Moi's bridge then crosses to Kakamega county.It flows south and then west, eventually flowing into Lake Victoria near the town of Port Victoria. ...

to form the

Yala Swamp The Yala Swamp is a wetland region of about in Western Kenya. Location The Yala Swamp at the mouth of the Yala River covers about along the northeastern shore of Lake Victoria. The swamp contains the Lake Kanyaboli, a freshwater deltaic wetl ...

on the border of Lake Victoria. The land along its course is mostly cultivated or used for grazing, with relatively few remnants of the original forest.

Soil erosion Soil erosion is the denudation or wearing away of the upper layer of soil. It is a form of soil degradation. This natural process is caused by the dynamic activity of erosive agents, that is, water, ice (glaciers), snow, air (wind), plants, and ...

is visible throughout the river basin, particularly in the lower parts. Projects are underway to exploit the river for hydroelectricity.

Course

The Yala River rises in the

Nandi Escarpment The Nandi Escarpment is an escarpment in Nandi County, Kenya. It marks the boundary between Kisumu and Nandi counties. It consists of numerous massive geological rocks ,one being Nandi rock. Monkeys and baboons are among common wildlife sightings. ...

in the

Rift Valley Province Rift Valley Province ( sw, Mkoa wa Bonde la Ufa) of Kenya, bordering Uganda, was one of Kenya's eight provinces, before the Kenyan general election, 2013. Rift Valley Province was the largest and one of the most economically important provinces i ...

, Kenya. It flows west for {{convert, 219, km to its mouth on

Kisumu County Kisumu County is one of 47 counties in the Republic of Kenya. Its borders follow those of the original Kisumu District, one of the former administrative districts of the former Nyanza Province in western Kenya. Its headquarters is Kisumu City ...

, Kenya.{{sfn, Okuna, 2019 It is one of the largest Kenyan rivers feeding Lake Victoria, with an average discharge of {{convert, 27.4, m3/s.{{sfn, Boye, Verchot, Zomer, 2008, p=4 The river contributes about 5% of the annual inflow to Lake Victoria.{{sfn, Identification of a multipurpose water resources ... The Yala River flows through a wide, mature valley that appears to have been rejuvenated during the tilting associated with the rifting movements of the mid-

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

. It runs swiftly over a rocky bed, with a notable absence of alluvial flats and terraces.{{sfn, Ominde, 1971, p=30 The main channel is about {{convert, 30, m wide, apart from the Yala Swamp.{{sfn, Identification of a multipurpose water resources ... The river runs through the southeast of the

Kakamega Forest Kakamega Forest is a tropical rainforest situated in the Kakamega County, Kakamega and Nandi_County, Nandi County of Kenya, northwest of the capital Nairobi, and near to the border with Uganda. It is Kenya's only tropical rainforest and is said to ...

, where it has a dramatic {{convert, 20, m waterfall.{{sfn, Mwangi, Chege, 2019, p=4 The

at the mouth of the river covers about {{convert, 175, km2 along the northern shore of Lake Victoria.{{sfn, Okuna, 2019 The swamp contains the {{convert, 1500, ha

Lake Kanyaboli Lake Kanyaboli is a lake in the Yala Swamp in western Kenya. It is important as a refuge for fish species that have almost disappeared from Lake Victoria. Location The Yala Swamp at the mouth of the Yala River covers about along the northern s ...

, a freshwater deltaic wetland with an average depth of {{convert, 3, m, which is fed by the floodwaters of the

Nzoia The Nzoia River is a Kenyan river, rising from Cherangany hills. It passes through Kapsara, Springer ,Moi's bridge then crosses to Kakamega county.It flows south and then west, eventually flowing into Lake Victoria near the town of Port Victoria. ...

and Yala rivers and by the backflow of water from Lake Victoria. The lake provides a refuge for several species of fish that are no longer present in Lake Victoria.{{sfn, Lake Kanyaboli – Kenya GNF In the past the Yala River flowed through the eastern 20% of the Yala Swamp into Lake Kanyaboli, then into the main swamp, and then through a small gulf into Lake Victoria. Today the eastern part of the swamp has been drained, and the river flows directly into the {{convert, 8000, ha main swamp. It is cut off from Lake Kanyaboli by a silt-clay dyke. Lake Kanyaboli now receives its water from the surrounding catchment area and from back-seepage from the swamp. The river's gulf has been cut off from the lake by a culvert, which created the {{convert, 500, ha Lake Sare through back-flooding.{{sfn, Yala Swamp Complex ... BirdLife Lake Sare, with its direct link to Lake Victoria, is important in preserving the

cichlid Cichlids are fish from the family Cichlidae in the order Cichliformes. Cichlids were traditionally classed in a suborder, the Labroidei, along with the wrasses ( Labridae), in the order Perciformes, but molecular studies have contradicted this ...

fish fauna of Lake Victoria.{{sfn, Gichuki, Maithya, Masai, 2005, p=340 The river water enters Lake Victoria from Lake Sare through a channel crossed by a bridge that carries the C27 coastal highway along the Goye causeway.{{sfn, Relation: Yala (8873639){{sfn, Gichuki, Maithya, Masai, 2005, p=341

Basin

The Yala River drainage basin covers {{convert, 3351, km2.{{sfn, Okuna, 2019 An ecosystem management study of the Yala and

river basins issued a baseline report in 2008. It studied three representative {{convert, 10, by, 10, km2 blocks of land in the Yala basin.{{sfn, Boye, Verchot, Zomer, 2008, p=5 In all three blocks much of the land was cultivated. Subsistence crops included

maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...

bean A bean is the seed of several plants in the family Fabaceae, which are used as vegetables for human or animal food. They can be cooked in many different ways, including boiling, frying, and baking, and are used in many traditional dishes th ...

sorghum ''Sorghum'' () is a genus of about 25 species of flowering plants in the grass family (Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species is grown for grain, while many othe ...

banana A banana is an elongated, edible fruit – botanically a berry – produced by several kinds of large herbaceous flowering plants in the genus ''Musa''. In some countries, bananas used for cooking may be called "plantains", distinguis ...

cassava ''Manihot esculenta'', common name, commonly called cassava (), manioc, or yuca (among numerous regional names), is a woody shrub of the spurge family, Euphorbiaceae, native to South America. Although a perennial plant, cassava is extensively ...

and

sweet potato The sweet potato or sweetpotato (''Ipomoea batatas'') is a dicotyledonous plant that belongs to the Convolvulus, bindweed or morning glory family (biology), family, Convolvulaceae. Its large, starchy, sweet-tasting tuberous roots are used as a r ...

, while cash crops included

tea Tea is an aromatic beverage prepared by pouring hot or boiling water over cured or fresh leaves of '' Camellia sinensis'', an evergreen shrub native to East Asia which probably originated in the borderlands of southwestern China and northe ...

wheat Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...

and

mango A mango is an edible stone fruit produced by the tropical tree ''Mangifera indica''. It is believed to have originated in the region between northwestern Myanmar, Bangladesh, and northeastern India. ''M. indica'' has been cultivated in South a ...

.{{sfn, Boye, Verchot, Zomer, 2008, p=9, 27, 43 The Upper Yala Block in the

Uasin Gishu District Uasin Gishu County is one of the 47 counties of Kenya located in the former Rift Valley Province. Eldoret has the county's largest population center as well as its administrative and commercial center. “It lies between longitudes 34 degrees 50 ...

includes

Lake Lessos Kesses Dam (or Lake Lessos) is a small man-made lake in Kenya. It is one of the sources of the Yala River. It is used as a source of water for irrigation and domestic use, and also for boating and other water activities. Location Kesses Dam is in ...

, one of the Yala River's main sources. The block has level terrain with medium gradient hills with shallow depressions. There are wetlands and small permanent streams. The farms are large and there is little subsistence agriculture. The cultivated land is interspersed with grasslands.{{sfn, Boye, Verchot, Zomer, 2008, p=41 Dairy production is important.{{sfn, Boye, Verchot, Zomer, 2008, p=43 22% of the plots showed soil erosion in 2008.{{sfn, Boye, Verchot, Zomer, 2008, p=46 The Middle Yala Block in

Vihiga District Vihiga County is an administrative region in the former Western Province of Kenya whose headquarters are in Mbale, the largest town in the county. The county has a population of 554,622 (2009 census) and an area of 563 km2. Formally a dist ...

and

Kakamega District Kakamega County is a county in the former Western Province of Kenya and borders Vihiga County to the South, Siaya County to the West, Bungoma and Trans Nzoia counties to the North and Nandi and Uasin Gishu counties to the East. Its capital a ...

contains mountainous highlands with many small streams, and held clusters of wetlands. There are preserved remnants of forest throughout the block used for cultural purposes, and logging in the Kaimosi forest in the southeast of the block. Most of the farms are overcropped, without traditional rotation and fallow periods. The farms are managed better in the north of the block, with more trees and hedges, while in the southern part steep slopes are cultivated with no conservation measures.{{sfn, Boye, Verchot, Zomer, 2008, p=25 About half the block shows evidence of soil erosion.{{sfn, Boye, Verchot, Zomer, 2008, p=29 The Lower Yala block in

Kisumu District Kisumu County is one of 47 counties in the Republic of Kenya. Its borders follow those of the original Kisumu District, one of the former administrative districts of the former Nyanza Province in western Kenya. Its headquarters is Kisumu City ...

and

Siaya District Siaya County is one of the counties in the former Nyanza Province in the Western part of Kenya. It is bordered by Busia County to the north, Kakamega County and Vihiga County's to the northeast and Kisumu County to the southeast. It shares a wa ...

has low to medium gradient terrain with a few large hills. Most of the population are

Luo Luo may refer to: Luo peoples and languages *Luo peoples, an ethno-linguistic group of eastern and central Africa **Luo people of Kenya and Tanzania or Joluo, an ethnic group in western Kenya, eastern Uganda, and northern Tanzania. ***Luoland, the ...

, but in some areas the people are mainly

Luhya Luhya or Abaluyia may refer to: * Luhya people * Luhya language Luhya (; also Luyia, Luhia or Luhiya) is a Bantu language of western Kenya. Dialects The various Luhya tribes speak several related languages and dialects, though some of them are ...

.{{sfn, Boye, Verchot, Zomer, 2008, p=9 About 43% of the land is used for crops, and 55% for grazing livestock.{{sfn, Boye, Verchot, Zomer, 2008, p=13 Livestock includes cows, bulls, chickens, goats and sheep.{{sfn, Boye, Verchot, Zomer, 2008, p=18 There are few trees, and widespread soil erosion.{{sfn, Boye, Verchot, Zomer, 2008, p=14

Hydroelectric projects

As of 2016 a feasibility study had been completed for development of the Nandi Forest dam to support irrigation, water supply and power generation. The power plant would have two 25 MW Pelton turbines and would supply 185 GWh annually.{{sfn, Lahmeyer International GmbH, 2016, p=59 In April 2020 it was announced that Tembo Power of Mauritius, along with Metier and WK Construction of South Africa had signed an agreement for development of a

run-of-the-river hydroelectricity Run-of-river hydroelectricity (ROR) or run-of-the-river hydroelectricity is a type of hydroelectric generation plant whereby little or no water storage is provided. Run-of-the-river power plants may have no water storage at all or a limited amou ...

plant on the Yala River.{{sfn, Kenya: Tembo Power ... The Kaptis Hydroelectric Power Station was to have a 15MW capacity and would be operational by 2022. The project would cost $30 million. The electricity would be fed to the grid operated by the state-owned

Kenya Power and Lighting Company Kenya Power and Lighting Company, commonly referred to as Kenya Power or shortened KPLC, is a public liability company which transmits, distributes and retails electricity to customers throughout Kenya. Location KPLC headquarters are at Stima P ...

(KPLC).{{sfn, Takouleu, 2020 The power plant was to be located near the town of

Kakamega Kakamega is a town in western Kenya lying about 30 km north of the Equator. It is the headquarters of Kakamega County that has a population of 1,867,579 (2019 census). Kakamega is 52 km north of Kisumu, the tenth largest city in Ken ...

.{{sfn, Creamer, 2020

Ecological changes

A study of discharge data from 1950 to 2000 showed a general increase in discharge. This may be due to destruction of land cover, including indigenous forests.{{sfn, Sangale, Okungu, Opango, 2011, p=6 Yearly discharge of nutrients into the lake is about 1,000 tonnes of

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

and 102 tonnes of

phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...

.{{sfn, Boye, Verchot, Zomer, 2008, p=4 Threats to the river ecology include garbage from panning for minerals, oil spills in and near the river, deforestation and resulting river bank erosion, and sand extraction.{{sfn, Okuna, 2019 Development potential includes irrigation and drainage projects in the lower and middle parts of the basin, hydroelectricity, wetlands products, eco-tourism and water sports tourism, and perhaps

carbon sequestration Carbon sequestration is the process of storing carbon in a carbon pool. Carbon dioxide () is naturally captured from the atmosphere through biological, chemical, and physical processes. These changes can be accelerated through changes in land ...

.{{sfn, Identification of a multipurpose water resources ... Conversion of the wetlands for crop production must be carefully managed to ensure environmental sustainability. Sufficient wetlands must be maintained to control erosion and improve water quality, which in turn affects fisheries in the river and the adjacent lake. The watershed must also be rehabilitated to maintain farm productivity and to reduce erosion and sedimentation of the wetlands and river.{{sfn, Identification of a multipurpose water resources ... A 2005 report noted changes in Lake Sare that threatened the lake ecosystem through eutrophication and pollution. It recommended an inclusive management plan for the Yala swamp complex to prevent further degradation of the ecosystem.{{sfn, Gichuki, Maithya, Masai, 2005, , p=347 As of 2019 BirdLife International scored the threat to the swamp complex as high, and was pessimistic about action being taken.{{sfn, Yala Swamp Complex ... BirdLife

Notes

{{notes{{reflist, 25em {{commons category, Yala River

Sources

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