Evaluation of Stream Flow Prediction Capability of Hydrological Models in the Upper Blue Nile Basin, Ethiopia

This study aims to evaluate stream flow predication capability of three hydrological models including Parameter Efficient Semi-Distributed Watershed Model (PED-WM) model, Hydrologiska Byrans Vattenbalansavdelning (HBV) and Hydraulic Engineering Center-Hydrologic Modeling System (HEC-HMS) in range of sizes of watersheds, Upper Blue Nile Basin, Ethiopia. The model efficiency on daily time scale during calibration period for PED-W (NSE = 0.76, 0.81 and 0.57), HBV-IHMS (NSE = 0.68, 0.79 and 0.59) and HEC-HMS (NSE = 0.63, 0.68 and 0.48) were obtained for Anjeni, Gumara and Main Belles watersheds respectively. Similarly, for validation period PED-W (NSE = 0.6, 0.73 and 0.37), HBV-IHMS (NSE = 0.56, 0.79 and 0.55) and HECHMS (NSE = 0.52, 0.74 and 0.37) were obtained for Anjeni, Gumara and Main Belles watersheds respectively. Similarly, the model performances on monthly time steps were also varied among three hydrological models and the results better than the daily time scale. In PED-W, saturation excess is the main direct runoff process. The overall model performance indicated that PED-W model was better than the other two models. The result indicates that the models in the highlands of Ethiopia are dominantly dependent on the runoff mechanism dominantly on saturation excess runoff mechanism. Hence, there should be an approach to integrate climate region specific model in our water resource development system for predicting stream flow for ungagged catchments.