The development of a grid-based hydrological model of the Blue Nile and the sensitivity of Nile River discharge to climate change

In order to evaluate the implications of climate change for the Nile a model of the Blue Nile was developed. The Blue Nile drains the Ethiopian highlands and provides roughly 50% of the Main Nile flow. The Blue Nile model was driven with the temperature and precipitation changes from three General Circulation Model climate scenarios. The differences in the resulting magnitude and direction of changes in runoff highlight the inter-model differences in future climate change scenarios. A "dry' case, "wet' case and Composite case produced -8%, +22% and -0.4% changes in mean annual runoff in the Blue Nile, respectively. None of the scenarios suggested any change in the seasonal distribution of runoff. Sensitivity analysis with hypothetical climate changes show that runoff is more sensitive to changes in precipitation than temperature. This sensitivity is affected by the runoff ratio, with grid cells possessing low runoff ratios being more sensitive than those with high ratios