Remote sensing of crop water requirements in orange orchards using high-spatial-resolution sensors

With the aim to derive crop water requirements (ETp) for an irrigated area covered by orange orchard in Sicily, Quick Bird and ASTER TERRA high resolution satellites data were used and compared with reference to their different spatial and spectral resolution. Satellites data allowed to improve the monitoring of canopy development in the irrigated area by identifying biophysical vegetation variable (LAI, albedo, vegetation indicators, etc); this information was successively used for the evaluation of maximum crop water needs by means of the well known Penman-Monteith equation. The paper results evidence the importance of very-high resolution sensors such as QuickBird in areas characterised by strong spatial heterogeneity. The algorithms applied to estimate the canopy parameters and the crop water requirements were applied by considering different levels of radiometric calibration of the satellite data, which produced marked differences in the final results.