COMPARING SEVEN DIFFERENT REFERENCE EVAPOTRANSPIRATION EQUATIONS WITH PENMAN-MONTEITH FOR ANTALYA, TURKEY

Evapotranspiration (ET) is one of the most difficult processes in nature. The most accurate and reliable method to determine ET is lysimeter, which is difficult, expensive and time-consuming. On the other hand, ET can be estimated using reference crop evapotranspiration (ETo) and crop coefficient (kc). easily Many ETo equations using meteorological data have been developed. The most widely accepted equation for ETo is FAO-56 Penman-Monteith (FAO-56 PM) equation. However, FAO-56 PM equation needs numerous meteorological data and is hard to measure for farmers. For this reason, equations which need less meteorological data have been gaining importance. Characteristic Mediterranean climate prevails in coastal areas of Antalya, Turkey. In the present study, long term data (1985 to 2015) obtained from meteorological stations was used to compute ETo in Antalya. Seven different ETo equations (Penman, FAO 24 Penman, Hargreaves, Turc, Priestley-Taylor, FAO 24 Pan, Christiansen Pan) were compared with FAO-56 PM. It was shown that the Turc equation gives results close to FAO-56 PM equation.