**Abstract**

The Kayanga/Geba river basin is a transboundary basin shared between Guinea, Senegal and Guinea-Bissau. It concentrates important natural resources, notably water resources on which Senegal and Guinea-Bissau are particularly dependent. The drastic reduction of these water resources due to rainfall variability and climate change has had an impact on agricultural production in the basin; hence the hydro-agricultural developments, in Senegalese territory, boost socio-economic activities by increasing productivity in both the rainy and dry seasons. The negative effects of these developments go beyond administrative boundaries. The transboundary management of this basin is a real challenge because the dams built in Senegal do not have the legal status of common dams of the OMVG whose mission is to promote cooperation between its member states. This article first analyses water control and some of the negative impacts of hydro-agricultural developments, and then the cooperation initiatives that the OMVG is trying to implement for rational and harmonious exploitation of the common resources of this basin.

**Keywords:** water control, transboundary water system, sub-regional cooperation, Kayanga/Geba basin
