Balanço de energia e evapotranspiração em cultivo de mandioca industrial

Abstract

The reduced number of surface information available for the source of evapotranspiration (ET) is driven by surface water demand studies. The surface renewal method (SR) method is an example, based on ramps of air temperature measured at high frequency by means of an ultra-thin thermocouple, it estimates the sensible heat flux (H). As the other components of the energy balance (radiation balance and heat flux in the ground) can be measured using low frequency instruments, the balance solution is thus complete. The objective of this work was the evapotranspiration of a processing cassava crop. The work was carried out in an industrial cassava area in the municipality of Laje, Bahia, Brazil. A micrometeorological tower was installed to assess the suitability of the method in estimating H on industrial cassava cultivation via calibration in relation to a eddy covariance (EC) system, this consisting of a 3D anemometer. Modeling of ET via remote sensing was performed using METRIC, SAFER and proposed Simplified Remote Sensing of Evapotranspiration (SRSE). The SR method was found to be adequate for estimatin the sensible heat flux (H) over a calibration coefficient equal to 0.96. Under unstable atmospheric conditions (daytime) the SR method presented better performance for estimating H in relation to stable conditions (nighttime). The SR method presents consistent results in estimating the sensible heat flux (H), having a EC as a reference, in industrial cassava cultivation with a high degree of correlation (R2> 0.90). In quantitative terms, the total ET of an industrial cassava crop in rainfed, under the conditions of the Bahia Reconcavo, was on average 160.01 mm in the tuber formation phase. From surface measurements, remote sensing techniques can be used for the spatial evaluation and quantification of ET. The simplification of the ET estimation in an industrial cassava area, presented coherent results and for using a reduced number of variables, thus being able to be applied with collection methodologies with greater temporal and spatial resolution.