Upstream-downstream linkages of hydrological processes in the nile river basin
Book Chapter
Berhanu, B, Seleshi, Y, Amare, M et al. (2015). Upstream-downstream linkages of hydrological processes in the nile river basin
. 207-223. 10.1007/978-3-319-18787-7_11
Berhanu, B, Seleshi, Y, Amare, M et al. (2015). Upstream-downstream linkages of hydrological processes in the nile river basin
. 207-223. 10.1007/978-3-319-18787-7_11
The various used of water in large transboundary river basins like the Nile River will require an understanding of the upstream-downstream hydrological linkages and impacts for better planning and management of the shared resources. Related to this understanding, the hydrological processes in the three broadly classified zones (headwaters zone, transitional zone and depositional zone) have paramount importance in the decision-making process of basin-wide water uses. Particularly, changes in the headwater zone at the Ethiopian highlands (the Blue Nile sub-basin) will have the most significant connectivity to the downstream water uses and hydrological regimes. If we compare the combination effects of the rainfall amount received by in three sub-basins (Bahr-EL-Ghazal Blue Nile and Equatorial Lakes Basin), and their larger drainage area, the two sub-basins (Bahr-El-Ghazal and Equatorial Lakes Basin) receive much greater than that of the Blue Nile sub-basin. But the contribution of flow by the western basins is comparatively low. This study uses Geographical Information System (GIS) as the base tool and 30 m SRTM Digital elevation model, high resolution mean monthly rainfall, and multi-stations (226) mean monthly potential evapotranspiration data for analysing the hydrological upstream-downstream connectivity. With these input data, the analysis has confirmed that the upstream and downstream linkages in the Nile River Basin is largely dependent on the extent of the transitional zone, in which the releasing function is more characterised by the evaporation process than runoff. Thus, under the current setting, the dependency of the hydrological system for the downstream reach/zone of the Nile River basin on the processes of the Blue Nile sub-basin is more significant due to the short extent of the transitional zone in this sub-basin.
