Use of automated weather stations and mathematical models to determine evapotranspiration

Evapotranspiration is an essential variable in water management and irrigation planning. Hence the importance of quantifying it and analyzing the methods that most satisfactorily estimate evapotranspiration on the local and basin levels. Therefore, the objective of this study was to estimate reference evapotranspiration (ET0) based on standard weather data using the mathematical models Penman-Monteith FAO, Blaney-Criddle, Hargreaves-Samani and the evaporimeter tank method, and to compare the results from applying the four methods in two Nazas River sub-basins. Three automated weather station networks located in the Nazas River were used to monitor and record the climate variables used as input in mathematical models. Two of the networks were in the lower basin (Cenid Raspa facilities with the David brand and Las Villas facilities with Motorola) and one was in the middle basin (David brand). The results indicated a higher ET, for the lower basin than for the middle basin of the Nazas River, with greater clarity from March to September, implying a higher irrigation volume for this zone. Moreover, based on the analysis of the methods and the comparison to the Penman-Monteith FAO as reference, the Doorenbos-Pruitt and Blaney Criddle models are recommended to estimate evapotranspiration in the lower and middle Nazas River basins, respectively, when lacking sufficient variables for the use of the Penman-Monteith FAO model.