ABSTRACT
For a long time, reference evapotranspiration has been considered to be and called potential evapotranspiration. From a theoretical point of view, this “potential” evaporation is defined from a mathematical concept and represents the maximum limit value of water that can be evaporated in a given climate for a soil cover that is constantly well supplied with water. Some scientists have pointed out a problem with this definition: quite often, the measurements used in the analytical expressions for calculating the “potential” evapotranspiration are not measured under meteorological conditions that could qualify as “potential” (Lhomme, 1997). This is why it is more prudent to employ the concept of reference evapotranspiration, which does not require the existence of any particular meteorological situation, on the condition that the crop is adequately watered.
