COMPARISON AND EVALUATION OF THE MODIFIED OPTIMIZED TEMPERATURE BASED EVAPOTRANSPIRATION MODEL WITH HARGREAVES AND PRESLEY TAYLOR METHOD IN SELECTED METEOROLOGICAL STATIONS IN ETHIOPIA

Abstract

Because it produces 15% of the water vapour in the atmosphere, evapotranspiration is a crucial step in the water cycle. In order to allocate water effectively, manage irrigation, assess the effects of shifting land use on water yield, evaluate the environment, and establish best management practises to safeguard surface and groundwater quantity and quality, accurate quantification of ET is essential. The Penman method was modified in 1965 by Monteith through incorporating the aerodynamic resistance and surface resistance factors, leading to the generation of the well-known Penman-Monteith method, which can be directly used to calculate ET. In this research work two evapotranspiration models namely one Modified Optimized Temesgen Melese ET-TM and two Modified Hargreaves methods of ET estimation models were compared with the Penman Monteith method interms of statistical parameter and model performance parameters. In this research work the Modified Optimized Temesgen Melese ET TM ET estimation models have shown good model performance in terms of R2 slope and intercept as compared with the. Penman-Monteith method.But the Hargreaves ET estimation method was show satisfactory model performance for Debrabirhan and Mekelle stations, poor value for Addis Ababa and good model performance for Dessie. Moreover all the other statistical parameters such as CE, RMSE and MPE have also shown in the results. Modified Optimized Temesgen Melese method should be compared with Penmann-Montieth (PM) method which is the standard ET estimation method