Evaluation of evapotranspiration methods to replace penman- monteith method in the absence of required climatic data in order to have a better Irrigation scheduling

Abstract

Evapotranspiration (ET) can be identified as a key function of vegetation which develops interaction in between climatologic, hydrological and terrestrial environments. Though there are number of climatologic methods are available to calculate ET such as Penman- MonteithMethod(PMM), Blany-Criddle Method(BCM), Radiation Method (RM), Hargreaves- Samani Method(HSM), Linacre Method(LM), Makkink Method(MM) and Turc Method(TM),in practice Penman- Monteith Method is used since it is likely to provide the most satisfactory result. But, it is not easier to obtain all types of climatic data since malfunctioning ofweather stations.However, the method selected to estimate ET should produce reasonable result with minimum number of climatic data. Thus, this attempt was taken in order to identify the most suitable method to utilize in various months to calculate ET considering the quality of result and input data requirement.According to the obtained results both Hargreves- Samani and Linacre Methods have shown reasonable values to replace PMM. Therefore Irrigation demand can be predicted and will be able to plan fairly successful irrigation scheduling in the field.