Abstract
The reference crop evapotranspiration (ET^sub r^) for four areas in Saudi Arabia was estimated using five different methods: FAO-Penman, Jensen-Haise, Blaney & Criddle, pan evaporation, and calibrated FAO-Penman under local conditions (Penman^sub -SA^). Comparison was also made between the estimated ET^sub r^ and the measured ET^sub r^ of alfalfa grown in lysimeters in the Riyadh area. Regression analysis revealed that estimated ET^sub r^ values were highly correlated with measured ET^sub r^ values. In addition, linear regression relationships between ET^sub r^ values estimated by the Penman^sub -SA^ method and other methods were determined. The results of this study indicated that the calibrated Penman^sub -SA^ method can be transferred successfully to other locations, and this method could be used for the estimation of ET^sub r^ values in all areas in the southern region of Saudi Arabia.[PUBLICATION ABSTRACT]