Remote sensing to estimate ET-fluxes and the performance of an irrigation district in southern Italy

Satellite remote sensed data on canopy biophysical properties, ground data and agro-meteorologicalinformation were combined to estimate evapotranspiration (ET) fluxes of orange orchards using amodified Penman–Monteith equation. The study was carried out during the irrigation season 2004 in anirrigation district, cover for about 95% with orange groves, of 1550 ha located in eastern Sicily (Italy).The spatial pattern in ET-fluxes have been analysed using IKONOS high-resolution satellite and hyperspectralground data acquired and processed for the study-area. The remote estimates of ET-fluxesvaried between 1.3 and 5.7 mm/day, with a daily average value of about 4.2 mm, showing a goodagreement with crop ET values determined as residual of soil water balance of selected ground controlsites. Crop coefficient estimates ranged between 0.22 and 1.08 showing positive correlations withpercentages of ground cover (Cg) increasing from 30 to 80% ground shading and with LAI values. Bycomparing ET estimates with water volumes supplied in each sub-district of the study-area, theperformance indicator ‘‘IP’’ was evaluated, allowing to rank the conditions of un-fulfilment of cropwater requirements by public and private water distribution systems. Generally, out of 29 sub-districts,14 had ‘‘IP’’ values less than 50%, revealing a sub-optimal water supply for the study-area.