Percentage Empirical Modelling of Reference Evapotranspiration in a Semi – Arid Region
1Edebeatu, C. C., 2Okujagu, C. U. & 2Ononugbo, Philomina C.
1,2Department of Physics & Industrial Physics, Madonna University, Nigeria
2Department of Physics, University of Port Harcourt, Nigeria
Corresponding Author:Email: edebeatuc@yahoo.com
ABSTRACT
Three reference evapotranspiration (ETo) models and one measured / observed (ETo(m)) were compared using percentage format. Among them the standardized Penman – Monteith model given by Food and Agricultural Organisation (FAO), hereby refer to as FPM 56. One empirical temperature based and one empirical radiation based is among the models used to predict reference evapotranspiration in the semi – arid region of Nigeria. The three models and the observed model were compared to the standard ETo table, alongside the ETo modelled by the FPM 56. The results showed that percentage modelling approach could be used as an alternative to modelling ETo, and again that the Allen’s standard ETo table is good comparison format when evaluating ETo, apart from the normal use of the modelled value within the research work itself, which may not provide the appropriated water requirement for the agricultural field or the need that satisfies the environmental water requirements. The empirical models predicted better results for the semi – arid region closest to the standard ETo table. The results of the percentage statistical comparisons provided a confident statistical justification for the ranking of the compared models.
Keywords: Reference evapotranspiration, Percentage ETo, standard Allen table, semi – arid region
