This work presents a computer program denominated "Sistema de Estimativa da Evapotranspiração (SEVAP)" with the objective of computing the reference evapotranspiration through different methods. The methods presented in the SEVAP program are: Penman-Monteith, Hargreaves, Jensen-Haise, Linacre, Makkink, Priestley & Taylor, Pan evaporation and Thornthwaite. The performance of the software program was evaluated with climatological data of Petrolina station, Pernambuco state. Mean monthly data and daily data (March to August 2002) of maximum and minimum air temperatures, relative humidity, insolation, wind velocity, Class A pan evaporation and solar radiation were used. The results show that the program produces accurate evapotranspiration values on a monthly and daily basis. In the absence of insolation and wind velocity data the Penman-Monteith method can be replaced by Hargreaves method, with good accuracy.
computer program; Penman-Monteith approach; software
