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{{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 Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...
, 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 tropics, tropical lake, and the world's second-largest fresh water lake by surface are ...
, 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 in western Kenya, a tributary of
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 tropics, tropical lake, and the world's second-largest fresh water lake by surface are ...
. It generally flows fast over a rocky bed through a wide valley before joining the Nzoia River to form the Yala Swamp 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 Topsoil, 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, Atmosphere of Ea ...
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 in the
Rift Valley Province Rift Valley Province () of Kenya, bordering Uganda, was one of Kenya's eight provinces, before the 2013 Kenyan general election. Rift Valley Province was the largest and one of the most economically important provinces in Kenya. It was dominated ...
, Kenya. It flows west for {{convert, 219, km to its mouth on
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 tropics, tropical lake, and the world's second-largest fresh water lake by surface are ...
in
Siaya County Siaya County is one of the counties in the former Nyanza Province in western Kenya. It is bordered by Busia County to the north, Kakamega County, and Vihiga County to the northeast and Kisumu County to the southeast. It shares a water border ...
, 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 ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
. 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, Vihiga County, Vihiga, and Nandi_County, Nandi counties of Kenya, northwest of the capital Nairobi, and near the border with Uganda. It is Kenya's only tropical r ...
, where it has a dramatic {{convert, 20, m, adj=on waterfall.{{sfn, Mwangi, Chege, 2019, p=4 The Yala Swamp at the mouth of the river covers about {{convert, 175, km2 along the northern shore of Lake Victoria.{{sfn, Okuna, 2019 The swamp contains {{convert, 1500, ha Lake Kanyaboli, a freshwater deltaic wetland with an average depth of {{convert, 3, m, which is fed by the floodwaters of the Nzoia 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 a large, diverse, and widespread family of percomorph fish in the family Cichlidae, order Cichliformes. At least 1,760 species have been scientifically described, making it one of the largest vertebrate families, with on ...
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 Nzoia 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''), also known as corn in North American English, is a tall stout grass that produces cereal grain. It was domesticated by indigenous peoples in southern Mexico about 9,000 years ago from wild teosinte. Native American ...
,
bean A bean is the seed of some plants in the legume family (Fabaceae) used as a vegetable for human consumption or animal feed. The seeds are often preserved through drying (a ''pulse''), but fresh beans are also sold. Dried beans are traditi ...
s,
sorghum ''Sorghum bicolor'', commonly called sorghum () and also known as great millet, broomcorn, guinea corn, durra, imphee, jowar, or milo, is a species in the Poaceae, grass genus ''Sorghum (genus), Sorghum'' cultivated for its grain. The grain i ...
,
banana A banana is an elongated, edible fruit – botanically a berry – produced by several kinds of large treelike herbaceous flowering plants in the genus '' Musa''. In some countries, cooking bananas are called plantains, distinguishing the ...
,
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, from Brazil, Paraguay and parts of the Andes. Although ...
and
sweet potato The sweet potato or sweetpotato (''Ipomoea batatas'') is a dicotyledonous plant in the morning glory family, Convolvulaceae. Its sizeable, starchy, sweet-tasting tuberous roots are used as a root vegetable, which is a staple food in parts of ...
, 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 south-western China and nor ...
,
wheat Wheat is a group of wild and crop domestication, domesticated Poaceae, grasses of the genus ''Triticum'' (). They are Agriculture, cultivated for their cereal grains, which are staple foods around the world. Well-known Taxonomy of wheat, whe ...
and
mango A mango is an edible stone fruit produced by the tropical tree '' Mangifera indica''. It originated from the region between northwestern Myanmar, Bangladesh, and northeastern India. ''M. indica'' has been cultivated in South and Southeast As ...
.{{sfn, Boye, Verchot, Zomer, 2008, p=9, 27, 43 The Upper Yala Block in the Uasin Gishu District includes Lake Lessos, 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 and
Kakamega District Kakamega District was a districts of Kenya, district in the Western Province, Kenya, Western Province of Kenya. Its capital town was Kakamega. It had a population of 603,422 people and an area of 1,395 km². Kakamega was created in 1963 by the ...
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 and Siaya District has low to medium gradient terrain with a few large hills. Most of the population are Luo, but in some areas the people are mainly
Luhya Luhya or Abaluyia may refer to: * Luhya people * Luhya language {{disambig Language and nationality disambiguation pages ...
.{{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 ...
(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). The town has an urban population of 107,227 (2019 census). Kakamega ...
.{{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 a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...
and 102 tonnes of
phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...
.{{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. It plays a crucial role in Climate change mitigation, limiting climate change by reducing the amount of Carbon dioxide in Earth's atmosphere, carbon dioxide in the atmosphe ...
.{{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

{{refbegin *{{citation , url=https://www.oceandocs.org/bitstream/handle/1834/6839/ktf0256.pdf?sequence=1&isAllowed=y , access-date=2021-03-07 , first1=Anja , last1=Boye , first2=Louis , last2=Verchot , first3=Robert , last3=Zomer , publisher=International Centre for Research in Agorforestry , location=Nairobi, Kenya , date=5 March 2008 , title=Baseline Report Yala and Nzoia River Basins , type=Western Kenya Integrated Ecosystem Management Project: Findings from the Baseline Surveys *{{citation , url=https://www.engineeringnews.co.za/article/debt-funders-appointed-for-15-mw-kenya-hydropower-project-2020-04-16/rep_id:4136 , access-date=2021-03-07 , last=Creamer , first=Terence , date=16 April 2020 , work=Engineering News , title=Debt funders appointed for 15 MW Kenya hydropower project *{{citation , url=https://www.researchgate.net/publication/268351503 , access-date=2021-03-07 , last1=Gichuki , first1=John , first2=Jacob , last2=Maithya , first3=D. M. , last3=Masai , title= Recent ecological changes in of Lake Sare, western Kenya , date=September 2005 , publisher=Kenya Marine and Fisheries Research Institute *{{citation , url=https://www.fcgkenya.co.ke/projects/identification-of-a-multipurpose-water-resources-development-project-in-the-yala-river-basin-in-kenya , access-date=2021-03-07 , title=Identification of a multipurpose water resources development project in the Yala River basin in Kenya , publisher=FCG Kenya , ref={{harvid, Identification of a multipurpose water resources ... *{{citation , url=https://www.africa-energy.com/article/kenya-tembo-power-develop-first-hydro-project-metier , access-date=2021-03-07 , title=Kenya: Tembo Power to develop first hydro project with Metier , date=17 April 2020 , work=African Energy , ref={{harvid, Kenya: Tembo Power ... *{{citation , url=https://docplayer.net/30808072-Development-of-a-power-generation-and-transmission-master-plan-kenya.html , access-date=2021-03-07 , author=Lahmeyer International GmbH , title=Development of a Power Generation and Transmission Master Plan, Kenya , date=May 2016 *{{citation , url=https://www.globalnature.org/35619/Living-Lakes/National-Networks/Network-East-Africa/Kanyaboli/resindex.aspx , access-date=2021-03-07 , title=Lake Kanyaboli – Kenya , publisher=Global Nature Fund , ref={{harvid, Lake Kanyaboli – Kenya GNF *{{citation , url=https://www.nema.go.ke/images/Docs/EIA_1680-1689/EIA_1683_Kakamega%20Forest%20fence%20ESIA%20Study-min.pdf , access-date=2021-03-07 , last1=Mwangi , first1=Peter , last2=Chege , first2=David , date=December 2019 , publisher=Kenya Wildlife Service , title=Environmental and Social Impact Assessment Study Report for the Proposed Kakamega Forest Conservation Fence Project *{{citation , url=https://www.grin.com/document/465661 , access-date=2021-03-06 , location=Munich , publisher=GRIN Verlag , last=Okuna , first=Patience , year=2019 , title=Threats to the survival of river Yala in Kenya *{{citation , last=Ominde, first=Simeon Hongo, title=Studies in East African Geography and Development, url=https://books.google.com/books?id=WgamvCA98usC&pg=PA30 , date=1971-01-01, publisher=University of California Press, isbn=978-0-520-02073-3 *{{citation , url=https://www.openstreetmap.org/relation/8873639#map=12/-0.0290/34.0623 , access-date=2021-03-07 , title=Relation: Yala (8873639) , work=OpenStreetMap , ref={{harvid, Relation: Yala (8873639) *{{citation , title=Variation of flow of water from Rivers Nzoia, Yala and Sio into Lake Victoria , year=2011 , last1=Sangale , first1=Felix , last2=Okungu , first2=John , last3=Opango , first3=Peterlis , publisher=Ministry of Environment and Natural Resources , url=http://repository.eac.int:8080/bitstream/handle/11671/824/Variation%20of%20flow%20of%20water%20from%20rivers%20Nzoia%2c%20Yala%20and%20Sio%20into%20Lake%20Victoria.pdf?sequence=1&isAllowed=y , access-date=2021-03-07 *{{citation , url=https://www.afrik21.africa/en/kenya-eaif-and-finnfund-finance-15-mw-kaptis-hydroelectric-project/ , access-date=2021-03-07 , last=Takouleu , first=Jean-Marie, date=20 April 2020 , title=KENYA: EAIF and Finnfund finance 15 MW Kaptis Hydroelectric Project , work=Afrik21 *{{citation , url=http://datazone.birdlife.org/site/factsheet/yala-swamp-complex-iba-kenya , access-date=2021-03-07 , title=Yala Swamp Complex , publisher=BirdLife International , ref={{harvid, Yala Swamp Complex ... BirdLife {{refend {{Rivers of Kenya {{authority control {{DEFAULTSORT: Rivers of Kenya