Rainfall-runoff modeling for the highland and catchment of Nile River Basin: a case study of Ruvubu River in Burundi

Different rainfall-runoff models ranging from the system type, linear, non-linear, lumped conceptual and distributed model such as HEC-HMS were applied and tested on Ruvubu catchment. The study catchment in Ruvu river basin, which has an area of 10.200km2. the missing river flow data was filled using procedures described in Kachroo et. al. 1988. The linear Perturbation model was used in filling the missing river flow data, using LTFM (msreal program). Rainfall was filled using the Inverse Distance Squared method. The evaporation was estimated using the Morto’s model and applying data generation procedures.. Lumped conceptual models, namely NAM, SMAR and XINANJIANG were applied and tested to the catchment. The model efficiencies were determined to be 45.6%, 39.59% and 65.54% respectively for the catchment. A semi-distributed model HEC-HMS was also applied and it gave a poor efficiency of R2: 49.6%. from the study it seems that the Linear Perturbation Model can be used as a beter river flow forecasting tool for the catchment studied.