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Assessing the performance of a large-scale irrigation system by estimations of actual evapotranspiration obtained by Landsat satellite images resampled with cubic convolution

2018; Elsevier BV; Volume: 75; Linguagem: Inglês

10.1016/j.jag.2018.10.016

1872-826X

Hassan Awada, Giuseppe Ciraolo, Antonino Maltese, Giuseppe Provenzano, M. Moreno, J.I. Córcoles,

Irrigation Practices and Water Management

• A new cost-effective indicator of assessing irrigation performance can be performed by using surface energy balance models. • Comparing hydrants delivered water volumes to surface energy balance actual evapotranspiration can be used for assessing irrigation systems . • A methodology to extract actual evapotranspiration was set to overcome the bias induced by cubic convolution resampling of satellite images. • It was observed that monthly irrigation volumes applied at plot scale were higher than actual evapotranspiration under full water supply . • It was demonstrated that a considerable amount of water could have been saved in the whole irrigation district over an entire irrigation season. Remote sensing techniques allow monitoring the Earth surface and acquiring worthwhile information that can be used efficiently in agro-hydrological systems. Satellite images associated to computational models represent reliable resources to estimate actual evapotranspiration fluxes, ET a , based on surface energy balance. The knowledge of ET a and its spatial distribution is crucial for a broad range of applications at different scales, from fields to large irrigation districts. In single plots and/or in irrigation districts, linking water volumes delivered to the plots with the estimations of remote sensed ET a can have a great potential to develop new cost-effective indicators of irrigation performance, as well as to increase water use efficiency. With the aim to assess the irrigation system performance and the opportunities to save irrigation water resources at the "SAT Llano Verde" district in Albacete, Castilla-La Mancha (Spain), the Surface Energy Balance Algorithm for Land (SEBAL) was applied on cloud-free Landsat 5 Thematic Mapper (TM) images, processed by cubic convolution resampling method, for three irrigation seasons (May to September 2006, 2007 and 2008). The model allowed quantifying instantaneous, daily, monthly and seasonal ET a over the irrigation district. The comparison between monthly irrigation volumes distributed by each hydrant and the corresponding spatially averaged ET a , obtained by assuming an overall efficiency of irrigation network equal to 85%, allowed the assessment of the irrigation system performance for the area served by each hydrant, as well as for the whole irrigation district. It was observed that in all the investigated years, irrigation volumes applied monthly by farmers resulted generally higher than the corresponding evapotranspiration fluxes retrieved by SEBAL, with the exception of May, in which abundant rainfall occurred. When considering the entire irrigation seasons, it was demonstrated that a considerable amount of water could have been saved in the district, respectively equal to 26.2, 28.0 and 16.4% of the total water consumption evaluated in the three years.