The RV Basin has an area of 131 423 km2. It has a long, narrow shape bordering South Sudan and Ethiopia in the north and Tanzania in the south. The bottom half of the basin is bordered by the Lake Victoria North and South basins to the west, and the Athi and Tana basins to the east. The central and northern part of the basin is bordered by Uganda to the west and the Ewaso Ng’iro North Basin to the east. The RV Basin covers about 23% of Kenya’s area and houses 13% of the total population of Kenya. Lake Turkana is located in the northern RV Basin and is the largest lake in Kenya. The major towns in the catchment are Nakuru, Narok, Kabarnet, Naivasha and Lodwar. Nakuru is the largest town in the basin and hosts an extensive industrial area.

The topography of the RV Basin varies from the mountainous areas in the central-southern part at elevations up to 2 600 masl to elevations of less than 500 masl at Lake Turkana in the north and about 600 masl at Lake Magadi in the far south. The RV Basin landforms are the result of volcanic activity creating complex landforms, plains and mountains. Lake Turkana in the north of the basin is the largest lake in the basin and has a drainage area of about 123 000 km2, including the Omo River catchment in Ethiopia. The lake has a surface area of approximately 7 500 km2 . The lake receives most of its inflow (more than 80%) from the Omo River, which enters the lake from Ethiopia in the North. The total population of the RV Basin according to Census 2019 is estimated as 5.78 million, which is equivalent to a population density of 44 persons/km. Most of the population in the RV Basin currently reside in rural settlements, with only 24% of the population being located in urban areas.

Land use in the RV Basin includes forest, grassland/rangeland and agricultural use. The Basin has a high population density and scattered urban and built-up areas in the middle sections of the Basin with the dominant land use being rain-fed agriculture and rangeland.