Simplify the triangle method for estimating evapotranspiration and its use in agrometeorological modeling

Daniela Fernanda da Silva Silva Fuzzo, Jansle Vieira Rocha


An aim of this paper was to assess the accuracy in estimating soybean yield proposed by DOORENBOS and KASSAM over a region in Brazil using the evapotranspiration fraction (EF) obtained from a simplified version of the triangle model, the counties analyzed were Toledo, Vera Cruz do Oeste, Cascavel, Campo Bonito, Medianeira and Serranópolis Iguaçu, in Paraná state, for crop years 2002/03 to 2011/12. A high accuracy of the data was found, the model values for the parameter d1 ("d1" modified Willmott) were between 0.8 and 0.95 in most counties, whereas the root mean squared error showed that there was low variation between 149,60 to 358,60 (kg ha-1). This means that the average of the data from the modified model (using the remotely determined evapotranspiration fraction) were statistically equal the average of the measured soybean crop data. The remote sensing input can be used as tools in the absence of surface information, serving as input data for assisting in agrometeorological modeling in order to estimate agricultural productivity of soybean.


crop yield; MODIS image; remote sensing; vegetation index.

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