Application of GR2M for Rainfall-Runoff Modeling in Kébir Rhumel Watershed, North East of Algeria

Rainfall-runoff modeling is a part of the Hydrological Sciences that is concerned with the hydrological cycle and aims at producing tools usable on different fields. In this paper we examined a mathematical model is named GR2M for simulation of monthly runoff depth in Kébir Rhumel watershed. The selected watershed area is less than 8710km . The inputs were rainfall and potential evapotranspiration. The performance of the GR2M 2 model was evaluated using four (04) model performance metrics. Parameter identifiability was analyzed on the basis of the shape of the posterior distribution of parameters. The four performance evaluation metrics showed that the model performed satisfactorily during calibration and validation in terms of the overall fit of observed and simulated stream flows, low flows and the runoff volumes. The Nash-Sutcliffe efficiency (NSE) was > 0.85, the coefficient of determination R was 0.87 and the percent error in peaks PEP was 4.71% during calibration. 2 Slight performance drops were noted during validation, the NSE was >0.80, the coefficient of determination R was 0.79 and the percent error in peaks PEP was 34.65%. Calibrated parameters values showed good 2 time-stability and were well identifiable with posterior parameter distributions having Gaussian shapes. It was concluded that, although the model only had two parameters, the model performed quite satisfactorily in the simulation of monthly flows which makes it a good tool for operational hydrology and water resources modeling, planning and management especially in small watersheds with similar climatology.