Orbital remote sensing to estimate evapotranspiration in a cotton cropping system irrigated by a centre pivot

Abstract

Evapotranspiration (ET) estimation is essential for adequate management of water resources. The main ways to quantify ET are based on the use of field sensors, class A tanks, Bowen's ratio method, turbulent vortex correlation analysis, use of lysimeters, and through Remote Sensing (RS), which allows estimating biophysical parameters based on satellite images. The objective of the research was to determine the effective evapotranspiration (ETe) of cotton plantations irrigated with a centre pivot, using the Surface Energy Balance Algorithm for Land (SEBAL), Mapping Evapotranspiration at High Resolution and with Internalized Calibration (METRIC) and Simple Algorithm for Evapotranspiration Retrieving (SAFER) methods. Comparisons were made for three agricultural years, using the R², RMSE, MAE, MBE and R statistics. The best performances in the crops were obtained with the SEBAL vs. SAFER models, which presented mean values of 0.54, -0.30 and 0.31 mm d-1 in RMSE, MBE and MAE, respectively. The data obtained by all three models can be applied to estimate ETe in irrigated cotton plantations and, consequently, their results can assist in irrigation management and in crop treatments