Évaluation de vingt méthodes d'estimation de l'évapotranspiration journalière de référence au Burkina Faso

Knowledge of evapotranspiration (ET) is very important for water resources planning and management. Several methods have been developed to estimate ET. Among them the PENMAN-MONTEITH method is recommended by the Food and Agriculture Organization as a reference method. However, its use is difficult in some areas particularly in developing countries where climate data are not always available. One of the alternatives is then to use methods integrating fewer climatic variables. This study aims to evaluate alternative evapotranspiration methods and to calibrate and validate the two best ones. Daily climate data (Tmax, Tmin, Sr, RHmax, RHmin and u2) of eight stations from 1998 to 2012 were used. Each of the twenty models was compared to evaluate ET0 estimated by the PENMAN-MONTEITH by determining different statistical indices. The results show that the methods of H.L. PENMAN (1963), W. ABTEW (1996), J.D. VALIANTZAS 1 and 3 (2012-a, 2012-b) and G.H. HARGREAVES (1975) have given the best estimations of the evapotranspiration. Among these five methods, the two best are retained for calibration and validation. After calibration, the PENMAN method logically provides the best estimation of reference evapotranspiration, in front of that of ABTEW.