Impact of greenhouse gas induced climate change on the runoff of the Upper Benue River (Cameroon)

The ever-increasing concentration of greenhouse gases in the earthʹs atmosphere is projected to cause important changes in climate patterns. In the Sahelian part of Cameroon, changes in temperature and rainfall would have an important impact on the availability of water resources. To evaluate vulnerability, future runoff over the economically important Upper Benue River is simulated using a hydrological water balance model. Two climate change experiments (HadCM2 and ECHAM4/OPYC3) provide the necessary input variables to the model, under various scenarios of IPCC, the Inter-governmental Panel on Climate Change. By 2100, depending on climate sensitivity, scenarios and climate models, rainfall is expected to increase in the range of 4–13% and temperature from 1 to 3°C. These lead to changes of 4–11% in annual potential evapotranspiration. Under the same conditions, changes in annual river flow range from −3 to +18%, i.e. −7 to +45 mm. The 45 mm maximum expected annual increase falls within the current variability of the river discharge, characterised by a standard deviation of 76 mm. Future development planning in the valley must take into account these impacts and their effects, both positive and negative.