Comparative Evaluation of Crop Evapotranspiration Estimation Methods in a Semi-Arid Region

Abstract

The aim of this study is to compare crop evapotranspiration in the Konya Plain over a period of 10 years calculated by different crop evapotranspiration estimation methods using data collected from four meteorological stations. Accurate ET estimation is vital for sustainable water management in agriculture, especially in areas where there is a limited availability of water. This study highlights how the various estimation methods, particularly the radiation equation, support water-efficient agriculture when full weather data are available. To achieve this, it calculates the water requirements of five widely cultivated crops in the region: sugar beet, maize (grain), sunflower, dry bean, and wheat. The results show a significant difference between the FAO Penman–Monteith method and each of the other methods. It is also observed that the ETc values calculated according to the radiation equation are higher for most of the stations than the ETc values calculated using the other methods. At Akşehir, the ETc of dry bean obtained by using the radiation equation ranges from 501 mm to 679 mm; at Beyşehir, it ranges from 544 mm to 727 mm; at Cihanbeyli, from 679 mm to 738 mm; and at Ereğli, it ranges from 725 mm to 767 mm. The ASCE Penman–Monteith equation recorded the lowest ETc at all meteorological stations for the 10-year period. The radiation equation can be recommended for areas where there are not enough meteorological data to calculate the FAO Penman–Monteith equation, which is considered the standard approach for determining the water requirements of plants.