Reference Evapotranspiration Estimation from Class «A» Pan in the Northwest of Uruguay

Authors

  • Alvaro Otero Instituto Nacional de Investigación Agropecuaria. INIA-Salto Grande. Casilla de Correo 68033. Salto. Uruguay.
  • Carmen Goñi Instituto Nacional de Investigación Agropecuaria. INIA-Salto Grande. Casilla de Correo 68033. Salto. Uruguay.
  • José Pedro Castaño Instituto Nacional de Investigación Agropecuaria. Grupo Agroclima y Sistemas de información. Ruta 48 km 10. Rincón del Colorado. Las Piedras. Uruguay

DOI:

https://doi.org/10.31285/AGRO.16.580

Keywords:

Penman-Monteith method, crop water requirements, evaporation, irrigation schedule

Abstract

Efficient water management in agriculture requires accurate estimation of the evapotranspiration. The difficulty in obtaining records of all the variables needed to estimate reference evapotranspiration (ETo) by the model proposed by PenmanMonteith-FAO56 (Allen et al., 1998), leads to the use of alternative methods, such as pan evaporation class «A» (Eo), which requires regional calibrations for successful implementation. This paper compares four methods for estimating the adjustment coefficient (Kp) of Eo over ETo: i) the procedure proposed by Snyder (1992); ii) by Allen et al. (1998); iii) by Puppo and García Petillo (2009); and iv) the Kp-combined obtained through the regression coefficient of Eo to ETo for the region under study. The regression coefficient values of Eo over ETo change slightly according to the average interval used, being 0.77, 0.75 and 0.73 for the monthly interval, decadic (10 days) and weekly. The estimation error decreases as we average at longer intervals. The procedure i) significantly overestimated ETo, while ii) underestimated both, with a mean absolute error of 0.49 and 0.86 mm respectively, while in iii) is 0.32 and the iv ) is 0.37 mm. Procedures iii) and iv) with constant values of Kp had the best performance for the northwestern region of Uruguay.

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Published

2012-06-01

How to Cite

1.
Otero A, Goñi C, Castaño JP. Reference Evapotranspiration Estimation from Class «A» Pan in the Northwest of Uruguay. Agrocienc Urug [Internet]. 2012 Jun. 1 [cited 2024 Apr. 12];16(1):142-9. Available from: https://agrocienciauruguay.uy/index.php/agrociencia/article/view/580

Issue

Section

Soil and Water
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