Umudike Journal of Engineering and Technology

Climatic parameters are the main inputs in the evaluation of reference evapotranspiration, (ET_o) and crop evapotranspiration, ET_c.  Reference evapotranspiration is mostly determined by indirect methods using empirical models, such as FAO-56 Penman-Monteith (PM) model which is the most universally accepted and recommended model. This model uses the largest number of climatic parameters in evaluating ET_o values. This study determines the relationship between reference evapotranspiration, (ET_o) and climatic parameters for Umudike environment. The FAO-56 PM model was used to calculate ET_o for the study. The first phase of the report considered three climatic parameters namely temperature, relative humidity and rainfall.  A simple linear statistical regression analysis of the calculated ET_o and each of the various climatic parameters of study area showed correlation coefficients of: + 0.636 for temperature; -0.977 for relative humidity and – 0.862 for rainfall; while the population regression coefficients were; + 0.300 for temperature; - 0.256 for relative humidity and 0.00326 for rainfall to the ET_o, for all the data, in a multiple regression analysis. The R Square was 0.976 and the Significance F value was 0.000639. The results obtained were compared with results of study by other researchers.