Mapeamento da evapotranspiração na bacia hidrográfica do baixo Jaguaribe usando técnicas de sensoriamento remoto.

Abstract

The water resources management of semi-arid lands in Brazil is of great importance since the hydrological regime of its intermittent rivers is critical. In this sense, the evapotranspiration is one the most important components of the hydrological cycle. The present work objectives the determination of evapotranspiration in the Low Jaguaribe basin based on satellite images and the SEBAL/METRIC algorithm. Five TM – Landsat 5 images and data collected in an automatic weather station installed on Frutacor Farm, in Quixere – CE were used. The ETr values were validated with energy balance components obtained by the eddy covariance method, in an experiment installed in a banana orchard during the period from August 2005 to September 2006. Three different procedures were applied for atmospheric correction of the albedo. The albedo and net radiation results presented good agreement with surface measurements. The latent heat flux values – LE obtained with SEBAL/METRIC algorithm were usually greater than those provided by eddy covariance measurements, but when comparisons were made with LE obtained by multiplying the banana crop Kc by ETo the mean relative error was equal to13.9%.The comparison between daily ETr from SEBAL/METRIC with ETr from eddy covariance presented a mean relative error of 13.4%. The main conclusion is that SEBAL/METRIC algorithm presented very consistent results and that it can be used for generation evapotranspiration maps in the Low Jaguaribe River basin.