Desempenho de métodos de cálculo do coeficiente de tanque para estimativa da evapotranspiração de referência

Abstract

There are different processes applicable to the suitable irrigation management, and among them there are those which use the reference evapotranspiration (ETo) estimation as a parameter. This research aimed to evaluate different methods for determining pan coefficient (Kp), used to estimate ETo, based on evaporation data of Class "A" pan (TCA). Daily meteorological data were collected at Principal Climatological Station, which is located at the Federal University of Lavras. The period of time analyzed was from 01/01/2004 to 12/31/2013. The standard ETo estimation was performed using Penman-Monteith-FAO (FAO-PM) method. The methods utilized to obtain Kp were: Allen et al. (1998), Cuenca (1989), Snyder (1992), Pereira et al. (1995), and Doorenbos & Pruitt (1977). The performance of these methods was evaluated by comparing the estimated ETo obtained by the PM-FAO method with ETo estimated by the TCA method with different Kp values. In the monthly scale all tested methodologies showed satisfactory performance. For the evaluation in daily scale, the best performance was the methodology proposed by Pereira et al. (1995).