Irrigation in Lleida. Results of several assessments of the Urgell canals district

Abstract

This paper describes the irrigated areas of Lleida province and their water demand as compared to the natural water supply. The results are presented of the irrigation assessments conducted on various scales by our research group over the past 20 years in the area irrigated by the Urgell canals, where flood irrigation is the primary method used. It has been observed that the quality of flood irrigation is highly conditioned by the type of soil. Likewise, the larger the extension of the irrigated area, the higher the efficiency of water use with respect to what is found in plots and small-scale irrigation areas. This fact is not only attributable to the suitability of soil types for flood irrigation but also to the reuse of water because of its scarcity. The advantages and disadvantages of modernising the irrigation systems and the different ways of carrying this out are appraised. Lastly, results are presented of a simulated modernisation of the area irrigated by the Urgell canals, with a discussion of the effects that such modernisation would have on the efficiency of water use. It is concluded, contrary to what is generally thought, that the modernisation of irrigation here would not entail any water savings or any release of water resources for other uses, but rather an increased consumption and a decrease in downstream water availability.

Keywords: water resources, irrigation, assessment, modernisation, Lleida, Urgell canals.