Modeling of Reference Evapotranspiration in Middle South Saurashtra Region of India Using Dominant meteorological Variables

Abstract

In this paper attempt is made to estimate reference evapotranspiration (ET_o) from standard meteorological observations. The FAO-56 Penman-Monteith method is the most physical, reliable and mostly used as a standard to verify other empirical methods. However, it needs a lot of different input parameters. Hence, in the present study, a model based on most dominant meteorological variables influencing ET_o is proposed to estimate ET_o in the Middle South Saurashtra region of Gujarat (India). The performance of five different alternative methods and proposed model is compared keeping the FAO-56 Penman-Monteith method as reference.

The models are evaluated by using Nash-Sutcliffe efficiency coefficient (E), (R²), (d_r), (RSR) and (MAE) statistical criterions. The results show that the developed model and Hargreaves and Samani (1985) method provide the most reliable results in estimation of (ET_o), and it can be recommended for estimating (ET_o) in the study region.