Estimating the potential evapo-transpiration and crop coefficient from climatic data in Middle Delta of Egypt

There are many empirical and theoretical equations to estimate the value of the potential evapo-transpiration (PET) under certain weather conditions. The relation between PET and climatic factors has the greatest role in the development of such equations. The main goal of this study is to propose empirical equations for estimating the PET of climatic data for Middle Delta of Egypt and modify the Blaney–Criddle equation using data in the period from 1990 to 2006. The climatic data during the period from 1990 to 2000 is used to propose the empirical equation and modified Blaney–Criddle equation. The result of the proposed equation is more accurate in calculating PET. Monthly crop coefficient (Kco) for crops cultivated in this area is estimated for the proposed equation in the study area and is compared with the measured values. Sensitivity analysis is used to quantify the impact of climatic parameters on the potential evapo-transpiration and crop coefficient.