Monitoring crop coefficient of orange orchards using energy balance and the remote sensed NDVI

The structure of vegetation is paramount in regulating the exchange of mass and energy across the biosphereatmosphereinterface. In particular, changes in vegetation density affected the partitioning of incoming solarenergy into sensible and latent heat fluxes that may result in persistent drought through reductions in agriculturalproductivity and in the water resources availability. Limited research with citrus orchards has shownimprovements to irrigation scheduling due to better water-use estimation and more appropriate timing ofirrigation when crop coefficient (Kc) estimate, derived from remotely sensed multispectral vegetation indices(VIs), are incorporated into irrigation-scheduling algorithms.The purpose of this article is the application of an empirical reflectance-based model for the estimation of Kc andevapotranspiration fluxes (ET) using ground observations on climatic data and high-resolution VIs from ASTERTERRA satellite imagery. The remote sensed Kc data were used in developing the relationship with thenormalized difference vegetation index (NDVI) for orange orchards during summer periods. Validation of remotesensed data on ET, Kc and vegetation features was deal through ground data observations and the resolution of theenergy balance to derive latent heat flux density (λE), using measures of net radiation (Rn) and soil heat fluxdensity (G) and estimate of sensible heat flux density (H) from high frequency temperature measurements(Surface Renewal technique).The chosen case study is that of an irrigation area covered by orange orchards located in Eastern Sicily (Italy)during the irrigation seasons 2005 and 2006.