A comparison between satellite- and model-based approaches developed in the ESA Irrigation+project framework to estimate irrigation quantities

Irrigation is the most impacting anthropogenic activity on the natural water cycle. Despite this, the current knowledge of irrigation extents and of the amounts of water used for such purpose is often not sufficient. Models and remote sensing technologies proved to be useful tools for monitoring irrigation dynamics. This study presents a comparison between two different approaches (one satellite-based and one model-based) aimed at estimating irrigation water amounts developed within the European Space Agency (ESA) Irrigation+ project. The project targets are: (i) the development of methods and algorithms to detect, map, and quantify irrigation at different spatial scales; (ii) the production of satellite-derived irrigation products; and (iii) the assessment of the impacts of irrigation on society and science. In particular, analyses carried out over two test sites in Italy where irrigation is practiced at different spatial scales are presented and discussed. The results highlight the capability of both approaches in reproducing the irrigation occurrence, and show a better performance of the satellite-based method in reproducing the actually occurred irrigation amounts.