National Irrigation Board managed rice and maize irrigation scheme at Bura

These are dams constructed with the irrigation scheme to hold or store water that will later be used for irrigation. The water in the dam comes from the Tana river and some harvested from the rainfall. The dam is lined in a manner that allows for ease of flow of the water into the main canals for supply to the farms. When the water level goes below the level where it can drain by gravity, then the community can pump the water. 
https://irrigation.go.ke/2022/11/03/bura-irrigation-scheme-the-land-of-crop-diversity/