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

The ever-increasing concentration of greenhouse gases in the earth's atmosp here is projected to cause important changes in climate patterns. In the Sa helian part of Cameroon. changes in temperature and rainfall would have an important impact on the availability of water resources. To evaluate vulner ability, future runoff over the economically important Upper Benue River is simulated using a hydrological water balance model. Two climate change exp eriments (HadCM2 and ECHAM4/OPYC3) provide the necessary input variables to the model, under various scenarios of IPCC, the Inter-governmental Panel o n 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 degreesC. 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 min maximum ex pected annual increase falls within the current variability of the river di scharge, characterised by a standard deviation of 76 mm. Future development planning in the valley must take into account these impacts and their effe cts, both positive and negative. (C) 2001 Elsevier Science B.V. All rights reserved.