Tana Basin Area (TBA)
Tana Basin Area is geographically situated in the south eastern part of Kenya, lying between latitudes 0o 30’ north and 2o 30’ south, and longitudes 37o 00’ east and 41o 00’ east. It borders with the following Basin areas. Ewaso Ng’iro North to the North, Rift Valley to the West, Athi to the Southwest and South, and Somalia and Indian Ocean to the East. The Tana basin covers an area of 126,026 km2, which is about 21% of the area of Kenya.
The TBA has over 80% of its area classified as arid and semi-arid lands (ASAL), with mean annual rainfall being 679 mm. Rainfall distribution is highly variable, ranging from less than 500 mm in Lower Tana to 2,400 mm in the highlands of Upper Tana. Rainfall is bimodal coming during the long rains of March – May, and short rains of October – November. The daily temperatures range from below 10 o C in the mountain highlands to over 30o C at the coast.
Counties covered by Tana Basin Area
The counties include; Kirinyaga, Nyeri, Embu, Meru, Muranga, Kitui, Tharaka-Nithi, Garissa, Tana River, Lamu and parts of Machakos, Kilifi, Isiolo, Nyandarua and Kiambu.
Water Resources in the Basin
The main rivers in TANA are:
Chania, Thika, Thiba, Ena, Thuci, Amboni, Gura, Ragati, Mathioya, Kathita, Mutonga, Sabasaba, Maragwa, Ura-Rujiweru, Tana, Sagana and Thangatha
Distribution of ground water resources in the Basin is as illustrated in the map below
Land Use in Tana Basin Area
- Water towers: Mt. Kenya, Aberdares, Nyambene Hills
- Wetlands: The major wetland areas are in Tana Delta, including mangrove swamps.
- Agriculture: Maize and beans are the main food crops whereas cash crops include tea and coffee located in the upper zones. There is irrigated agriculture producing rice in Mwea, as well as extensive horticulture for local and export markets. In the foot slopes of Mt. Kenya and Aberdares, dairy farming is widely practiced. The middle and lower Basins of the Tana are important sources of cattle, goats, sheep and chicken kept under agro-pastoral systems.
- Mining majorly consisting of Gypsum and Stone quarrying in Garissa. Sand harvesting is also common along ephemeral stream in the middle Basins.
- Commerce and Industry: Major towns in TBA are Nyeri, Embu, Meru, Muranga, Garissa, Thika, and Kitui. Administrative Counties in TBA includes the whole area of Nyeri, Embu, Meru, Muranga, Kirinyaga, Kitui, Tharaka-Nithi, Garissa, Tana River, Lamu and parts of Machakos, Kilifi, Isiolo, Nyandarua and Kiambu.
- In the Basin area, there are numerous industries such as; coffee and tea factories, rice milling and milk processing factories. The local communities provide labour to these industries from which they obtain income to supplement their subsistence activities.
- Tourism: The main tourism attraction areas include national parks such as Meru, Shaba, Tsavo East; National Reserves such as Mwea, Kora and The Kiunga Marine National Reserve is designated as a biosphere reserve by the UNESCO. The Tana Delta is the largest, most ecologically and socio-economically important wetlands in Kenya. It is internationally designated as a Ramsar site.
Protected Areas in TBA
Source: National Water Master Plan, 2030
Number of Wildlife Species
National Parks (N.P.)
Tsavo East N.P
South Eastern Kenya, inland from the Coast
Mt. Kenya N.P
East of the Rift Valley
Aberdares Mountain Ranges, Nyeri
National Reserves (N.R.)
Tana River Primate N.R
Tana River County
North east boundary of Meru N.P.
Mt. Kenya N.R.
East of the Rift Valley
Northeast of Kora N.P.
Ngai Ndethya N.R.
Next to Rahole N.R.
North East coast
South Kitui N.R
Northern area from Tsavo east N.P.
North Kitui N.R.
Kiunga Marine N.R.
180km North of Nairobi
Central Kenya, on the eastern edge of the RVCA
Water Demands in TBA
As per the NWMP 2030, the annual water demands were estimated for the year 2010 and projected for 2030 in TBA for the various subsectors. The available water resources, is estimated at 6,533 Million Cubic Meters/year in 2010
Tana Basin Area Water Quality Testing Laboratory
The Tana Water Quality Testing Laboratory was commissioned on 9th March, 2016. The laboratory will offer water and wastewater services which will specifically include:
Potable water analysis
For potable water, two types of analysis are distinguished i.e. Full Chemical Analysis (FCA) and bacteriological analysis. FCA deals with physical-chemical parameters of water e.g. pH, turbidity, mineral (ions) content etc. The bacteriological analysis focuses on total coliforms, E. coli and legionella ssp. Other bacteriological species will be analyzed on request.
Environmental water analysis
This focuses on water for environmental issues (e.g. regulations) and research. Water samples are from various sources; rivers, lakes, springs, dams etc. The nature of analysis depends on customer needs and may vary from FCA, bacteriological to specific parameters e.g. Biochemical oxygen demand.
This deals with analysis of wastewater from all sources including industry and domestic wastewater treatment plants. As such, we will help customers to meet environmental regulatory requirements. Parameters to be analyzed include Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), heavy metals, total suspended solids, among others.
Water treatment chemical analysis
Before any water treatment process is undertaken, the quality and composition of the chemicals used for treatment should be known. We will provide analytical services for soda ash, alum and chlorine products. In addition, we will determine chlorine demand for all water types as well as the alum dosage (floc test).
On request, our skilled and experienced staff will provide sampling services to our customers. This is important for ensuring sample integrity and reliability of analytical results.
Catchment Management Units (CMUs)
The geographical setting required the identification of suitable CMUs, which are groups of Catchments that share similar natural resource management issues. Tana Basin Area was subdivided into seventeen (17) CMUs. The CMUs are managed through five (5) sub-regional offices.
- The sub-regional office at Kerugoya (Thiba SRO), is responsible for the CMUs 4D, Ena, Thiba and Tana, Karaba;
- Meru SRO (Kathita-Mutonga) to manages Mutonga, Kathita and Ura/Tharaka;
- Murang’a (Upper Tana) office takes care of Sagana-Gura, Lower Sagana and Upper and Lower Thika;
- Kitui (Tiva-Tyaa) manages the Lower Reservoirs and the Tiva, and
- Garissa (Lower Tana) office is responsible for the Lower Tana and Ijara/Lamu.
CMUs are a collection of sub-catchment with the similar characteristics e.g. commercial areas or rangeland areas.
Major Water Resources Challenges in the TBA
The major challenges encountered in Tana Basin area can be summarized as follows:
- Water scarcity at different times of the year, as water users and uses are increasing for the same water resources
- Uneven distribution of water resources in time and space, with large areas being ASAL,
- Basin degradation especially on Mt. Kenya and on slopes of Aberdares ranges,
- Encroachment into the water Basin areas,
- Increased water demands
- Riparian and wetland encroachment
- High sediment loads (caused by Basin degradation) causing siltation of dams.
- Water use conflicts, across upstream/downstream users, and across sectors
- Pollution of water resources from both point and non-point pollution sources
- Soil erosion and overgrazing in the lower parts of the region
- Water inter-basin transfer
- Inefficient water use systems, especially irrigation methods
- Landslides in highland areas
- Sand mining, especially in the middle reaches of the Tana River
- Flooding, especially in the Lower Tana zones
- Groundwater salinity in the lower Tana and the coastal zone
- Inadequate awareness on water resource management
- Climate change impacts causing frequent droughts and floods
- Inadequate water resources assessment and monitoring network
- Insecurity risks associated with working within the mid and lower reaches of the Tana.
- Vandalism of installed water resources monitoring infrastructure.
- Inadequate water resource monitoring infrastructure
WRMA’s efforts in Curbing Water Conservation Concerns in TBA
- Commissioning of a Water Quality Testing laboratory at the TBA Regional Office on 9th March 2016, by Hon Eugene Wamalwa, Cabinet Secretary MWI. The laboratory will be used to offer water and wastewater services such as; Water treatment chemical analysis, Environmental water analysis, Wastewater analysis and Potable water analysis.
- Launch of Sub Basin Management plans for Water Resources Users Associations within the TBA region. A WRUA as recognized in the Water Act 2002, represent water users that have come together for cooperative management of water resources and conflict resolution. That the water resource users, being the principle beneficiary or direct stakeholder of the water resources, should be integrally involved in the management of the water resources. That since their livelihood is at stake, the water resource users can be mobilized to undertake water resource management activities that serve their best interests (e.g. surveillance on illegal or harmful activities, adoption of best land use practices, Basins management activities, verification of local information).
- Lamu Ground Water Conservation. The National Museums of Kenya and WRMA in recognition of the mandate of the two institutions as stipulated in the Water Act 2002 and National Museums and Heritage Act 2006, forged an alliance to conserve and protect the Sand Dunes by signing of an MOU to collaborate in the gazettement, conservation and protection of the Lamu Water Basin Area together with WRM activities in Lamu County.