This investigation was initiated due to the importance of using decision support tools for water
resources planning so as management and due to the significance of the Blue Nile together with
the impacts of population growth so as economic expansion. RIBASIM model was used to study
the effect of some proposed control structures on the Blue Nile basin. The model was set up using
readily available input data which includes river basin network schematization, hydrologic data
and model data characterizing each node so as the links. The model was calibrated using annual
volume-discharge of the Blue Nile basin. The yearly incomes were used to quantify the outflow
from the Blue Nile. The performance of the calibrated model was assessed with different
techniques.
A reasonable agreement was observed in the annual water balances and hydrographs' shape.
Confident with the calibration process results, the model was used for further analysis of the whole
Nile basin and elemental sub-basins related to future trends of the main river flow and its
hydrological components. Different scenarios were designed and the expected effects of
constructing the proposed dams on the yearly income of the Blue Nile were calculated.
It was found that, the yearly income would decrease by 2.17, 2.42, 2.26, 1.99, 10.24, 9.05 or
10.38% if 1, 2, 3, 4, 5, 6or 7 dams, respectively, were constructed. These results were based on a
randomly selected representative year to show the effect of the proposed dams on the yearly
income of the Blue Nile.