Modelling rainfall-runoff processes of the Chemoga and Jedeb meso-scale catchments in the Abay/Upper Blue Nile basin, Ethiopia

The objective of this study is to understand the rainfall-runoff processes of the meso-scale Chemoga and Jedeb catchments in the Abay/Upper Blue Nile basin, Ethiopia. Distributed conceptual modelling and different field data were used in the modelling process. Three different model representations with varying model complexity were employed to test the appropriate model structure. Parameters were conditioned within the Generalized Likelihood Uncertainty Estimation (GLUE) framework using both discharge and environmental isotope information indicating the ratio of new and old water during the wet season. It was demonstrated that the two catchments cannot be modelled equally well with the same model structure due to differences in the rainfall-runoff processes caused by different amounts of wetlands leading to different hydrological responses. Hence, a single model structure for the entire Abay/Upper Blue Nile cannot do justice to all the dominant hydrological processes in the various sub-catchments in the basin. Editor D. Koutsoyiannis; Guest editor D. Hughes