Estimation of daily evaporation from the dam reservoir using the energy budget method and comparison with common equations (case study: Ekbatan dam)

Document Type : Research Article


1 M.Sc. of Civil Engineering-Water and Hydraulic Structures, Department of Civil Engineering, Bu-Ali Sina University, Hamedan, Iran

2 Ph.D. in Water Engineering, Expert in Water Resources Basic Studies, Regional Water Company of Hamedan, Hamedan, Iran



Evaporation is known as one of the main factors in reducing surface water resources such as lakes and dam reservoirs. Due to the multitude of components affecting evaporation, its correct estimation has always been of interest to researchers in the field of hydrology. In this research, the daily evaporation from the surface of the Ekbatan dam reservoir has been estimated using the Bowen ratio energy budget method as the basic method and compared with the results of 20 different equations. Investigations indicate that the Brutsaert-Stricker equation with MSE, MAE, and RMSE values equal to 0.36, 0.41, and 0.60 mm/day, respectively, and the NSE and R2 equal to 0.97 and 0.98, respectively, had the best performance in estimating daily evaporation rate from the surface of Ekbatan dam reservoir. On the other hand, Harbeck and Ryan-Harleman equations, in the group of mass transfer equations, have performed the weakest. Also, the relationship presented in this research to calculate evaporation from Ekbatan dam reservoir using weather parameters and without the need to calculate thermal storage of water with MSE, MAE, and RMSE values equal to 0.81, 0.67 and 0.90 mm/day, respectively, and the NSE and R2 equal to 0.93 and 0.94, respectively, for the test data have a good performance in estimating the evaporation rate.


Main Subjects

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