An Evaluation of the Hargreaves-Samani Method for Estimating Evapotranspiration Under Semi-Arid Conditions

Authors

Yusuf Aydin, Gaziantep University, Nizip Vocational Training School, Department of Plant and Animal Production Organic Farming Programme, Samandöken Village-Nizip/Gaziantep, TurkeyFollow

Publication Date

9-1-2021

Abstract

It is suggested by the Food and Agriculture Organization of the United Nations (FAO) to use the FAO56-Penman-Monteith (FAO56-PM) model as the standard model in reference crop water consumption studies. However, the climate parameters required by the standard model cannot be fully and reliably obtained in under developed or developing countries. Hence, the Hargreaves-Samani (HS) equation is used as an alternative to the FAO56-PM model since it can be used for calculations with less climate data. In this study, ET_o-PM and ET_o-HS values calculated at 8 provinces in Southeastern Turkey using the IAM-ET_o software were evaluated and compared in order to examine whether the HS equation can be alternative to the FAO-PM equation or not. It was observed at the end of the study that the daily calculated ET_o-HS values yielded 16% overestimation on average compared with ET_o-PM. Statistically highest (RMSE: 1.32, MAE: 1.10, MR: 1.37, and PE: 36.86) and lowest (RMSE: 0.33, MAE: 0.24, MR: 0.96, and PE: 5.32) values were calculated for Batman and Mardin respectively. The mean values for the Southeastern Anatolia Region were calculated as RMSE: 0.64, MAE: 0.52, MR: 1.17, and PE: 16.04. It was identified in the light of these findings that the HS equation can be used as an alternative to FAO56-PM for the studied provinces.

Recommended Citation

Aydin, Yusuf (2021) "An Evaluation of the Hargreaves-Samani Method for Estimating Evapotranspiration Under Semi-Arid Conditions," The Philippine Agricultural Scientist: Vol. 104: No. 3, Article 9.
Available at: https://www.ukdr.uplb.edu.ph/pas/vol104/iss3/9