Fereshteh Ghiami-Shomami, Kohzo Kawasaki, Leonardo, Seirou Shinoda, Yanyang Fan
Received 2019/04/12, Accepted 2019/06/20, Published 2019/07/24

Fereshteh Ghiami-Shomami1), Kohzo Kawasaki2), Leonardo3), Seirou Shinoda3), Yanyang Fan3)

1) Graduate School of Engineering, Department of Mechanical and Civil Engineering, Gifu University, Japan
2) Graduate School of Natural Science and Technology, Department of Civil Engineering, Gifu University, Japan
3) Faculty of Engineering, Department of Civil Engineering, Gifu University, Japan

Estimation of reference evapotranspiration (ET₀) is important in hydrological studies. As climate change is predicted to cause changes in water resources and agriculture sectors, the possible implications of changes in different climate variables on ET₀ need to be understood. Sensitivity analysis was employed to illustrate the effects of perturbation in meteorological parameters (maximum and minimum air temperature (T_max and T_min), sunshine hours (n), maximum and minimum relative humidity (RH_max and RH_min)) and wind speed (u_z) on ET₀. ET₀ was calculated by The Food and Agriculture Organization of the United Nations (FAO) 56 Penman-Monteith approach using climate data from 1979–2017 for the Enbara and Futatsumori watersheds in forested mountain areas in Japan. We quantified the contributions of climatic factors to ET₀ at daily, monthly, seasonal and annual time scales. Daily results showed large fluctuations. According to the monthly and seasonal analysis, during warm seasons, T_max and n had more influence on ET₀, especially in May, while for the cold seasons, RH effect was dominant, especially in December. Based on the annual results, the factors most influencing ET₀ were T_max followed by n, u_z, RH and T_min. We also found that the response of ET₀ to changes in climatic parameters differs for sites with different topographic and geographic characteristics.

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