Comparison of methods for estimation of reference evapotranspiration in North-Central Plateau zone of Odisha

Estimation of Evapotranspiration is vital role for proper water management and efficient farming activities. A decision support system (DSS_ET) was developed which supports 22 ET0 estimation methods with varied options for calculation of various intermediate parameters. The objective of the study is to estimate ET0 in the North central Plateau zone of Odisha, using weather data of the respective locality and screening of methods to estimate ET0 close to FAO-56 Penman Monteith method. The FAO-24 Penman(c=1) and Turc methods yielded the highest (5.605 mm/day) and the lowest mean ET0 (4.201 mm/day) respectively. For this zone, the highest ET0 values  was found to be 10.32 mm/d for FAO-24 Penman(c=1) method followed by Businger-van Bavel (9.73 mm/d) and FAO-PPP-17-Penman (9.68 mm/d) in the month of May, whereas, lowest ET0 value was found in the month of December (2.54 mm/d) for the Priestly-Taylor method followed by 1982 Kimberly-Penman method (3.07 mm/d). Among all the methods, Penman-Monteith and Priestley-Taylor methods were ranked first and tenth respectively. For this zone, correction factor for Penman-Monteith and 1982 Kimberly-Penman methods approaches to one. The FAO-24 Penman (c=1) and Businger-van Bavel methods give more diversion from FAO-56 Penman-Monteith method.