Rift Valley Basin Area (RVBA)
RVBA is located in the central-western part of the country and covers an area of 130,452 km2, corresponding to 22.7% of the country’s area. It has a long and narrow shape with a length of about 800 km in the north-south direction, and about 100 km to 300 km wide in the east-west direction. It borders South Sudan and Ethiopia in the North, Tanzania in the south and Uganda to the West. It also borders Ewaso Ng’iro North, Tana, and Athi Basin areas in the eastern side, and Lake Victoria South and North Basin areas in the western side.
The topography of the Basin includes the low lying areas around Lake Turkana of 375 m above sea level (asl) in the north, the mountain areas of Aberdares of more than 3,000 m asl in the central part and Lake Magadi of 579 m asl in the South. The eastern and western flanks of the Basin area are characterised by graben slopes that are from the rift formation.
Water Resources in the Basin
RVBA drains internally into Lake Turkana to the North and Lake Natron to the south. Within this area there are several rivers draining into several lakes; Magadi, Naivasha, Elementaita, Nakuru, Bogoria, Baringo and Turkana while Solai and Kamnarok are minor lakes. Only Lake Baringo and Lake Naivasha have fresh water. Other lakes have saline water. Rivers originate from the Cherangani Hills, the Mau Forest Complex and the Aberdare Range. The Ewaso Ng’iro South river in the southern part originates from the Mau Forest Complex and flow southward across the border to Tanzania. Lake Turkana is the largest lake in Kenya with a surface area of 6,400 km2 and borders with Ethiopia. Its water resources are shared with Ethiopia. Major rivers flowing into L. Turkana on Kenyan side are the Turkwel and Kerio rivers. Turkwel river originates from Cherangani Hills and has a drainage area of 19,820 km2. Lake Magadi, located in the southern part of the RVBA, has the second-largest drainage area of 8,349km2, but the rivers pouring into this lake flow underground. Lake Baringo has the third largest drainage area of 6,530 km2 having the Perkerra and Molo rivers. Lake Naivasha with a drainage area of 3,128 km2,Lake Nakuru with a drainage area of 1,624 km2, Lake Bogoria with a drainage area of 1,137 km2, Lake Elementeita with a drainage area of 543 km2.
The northern part of the Basin is classified as arid land, while the central part is humid and southern part is semi-arid land. The mean annual rainfall ranges between 200 mm in the northern part to 1,200 mm in the central part of the Basin.
Water Demands by Subsector (LVNCA)
Water Demands (MCM/year)
Source: National Water Master Plain, 2030
The major land use types are forests, rangelands, croplands, rivers/water bodies and their riparian zones, urban and built-up areas, rural settlements, national park/reserve, springs and groundwater recharge areas and wetlands
- Water towers: Major water towers in the Basin include Mau, Cherangany, Elgon and Aberdares. These Basin areas can be classified as alarming (according to WRMA classification) with population and livelihood dependency on the Basin being the main cause.
- Agriculture: The area around Aberdare Ranges, Mau Complex, Cherengani, Tugen Hills receive moderate to high rainfall that is adequate for agricultural activities. The main agricultural activities include:
- Commercial farming which includes horticulture, floriculture and wheat farming;
- Livestock keeping involving the breeding and rearing of beef and dairy animals;
- Subsistence farming involving small-holder farmers practicing both cultivation and livestock keeping.
The horticulture/floriculture and subsistence farmers use irrigation during the dry seasons. The method of irrigation is mainly the sprinkling and flooding with the large scale farmers gradually changing to drip irrigation methods. The use of hydroponic technology has greatly reduced the amount of water used in the irrigated flower farms around Lake Naivasha. Some commercial farmers use boreholes and dams to supplement water from the rivers during the dry season.
- Pastoralism: Pastoralism dominates the socio-economic activities in the drier parts. Agro-pastoralism and bee-keeping are also important activities. Pastoral populations live in temporary settlements consisting of traditional make-shift houses.
Major Water Resources Management Challenges
- Basin degradation
- Water pollution, especially from non-functional sewerage systems, surface run-off from farmlands, industrial wastewater, poor solid waste management. Siltation in the lakes
- Flooding, especially in areas such as Narok, Lodwar, Mogotio and Marigat.
- Encroachment of riparian lands and wetlands
- Low compliance to WRM Rules 2007
- Inadequate water resources information
- Inadequate water resources to meet the various demands at different times of the year
- Storm runoff from unplanned settlements
- Water use conflicts