Performance assessment of SWAT and HEC-HMS model for runoff simulation of Toba watershed, Ethiopia

SWAT and HEC-HMS models are widely used hydrological models for runoff simulation. The performance of these models varies based on spatial and hydro-metrological characteristics of the watershed; These models are not applied on Toba watershed for daily runoff simulation. Therefore, the ultimate objective of this research is to check the performance of SWAT and HEC-HMS models in daily runoff simulation of Toba watershed which is located in Abbay River Basin, Ethiopia using the same input data set and methods. Land Use/Land cover (LU/LC), Soil, Digital Elevation model (DEM) and daily hydro-metrological data were the input data for both models. Therefore, the daily observed stream flow-data were used for both model calibration and validation. The statistical metrics used to measure the performance of both models were, R-2, NSE, PBIAS, and RMSE. The respective values for HEC-HMS were 0.85, 0.805, 33.7%, 22.7 m(3)/s during calibration, and 0.87, 0.84, 2.71%, 20.7 m(3)/s during validation. For SWAT model, the respective values were 0.69, 0.61, -26.1%, 31.85 m(3)/s, and 0.62, 0.54, -18.3, 35.24 m(3)/s during calibration and validation period. These values are at an acceptable level of accuracy. Therefore, both SWAT and HEC-HMS models well performed in the runoff simulation of Toba watershed. The overestimation of peak discharge and average runoff for dominantly cultivated land gives insight about the LU/LC characteristics of the watershed. The study can be used as a baseline scenario for future assessment of LU/LC and runoff potential.

Automated summary

This study evaluates the performance of SWAT and HEC-HMS models in daily runoff simulation in the Toba watershed in Abbay River Basin, Ethiopia using the same input data and methods. The results show that both models perform well in simulating runoff. Overestimation of peak discharge and average runoff for cultivated land provides insight into the characteristics of land use/land cover in the watershed. This study can serve as a baseline scenario for future assessments of land use/land cover and runoff potential.