Analysis of Virtual Irrigation Water. Application to Water Resources Management in a Mediterranean River Basin

Abstract

Virtual water, understood as the volume of water needed to produce a good or service, in the context of trade among countries, allows assessing the relative dependency of different countries on imported virtual water. The assessment of virtual water flows in virtual water trade studies is generally carried out at the national level, thus concealing the spatial variability of many countries that comprise a wide range of agro-climatic areas. A finer spatial resolution is needed to apply the virtual water concept with a view to improving local water resources management at the regional or basin scale. This paper presents a more detailed analysis of blue agricultural virtual water at sub-basin scale, which is aggregated to the basin scale for the Guadalquivir River basin in southern Spain. Given that around 80% of the available blue water resources of this region are used in agriculture, improving irrigation water management is of great interest to the basin water resources management. The main objective of this paper is to estimate the virtual irrigation water balance; an important component of the agricultural water footprint that provides additional information to the basin blue water balance and contributes to achieving a more rational and efficient management of basin water resources. Management recommendations focusing on the spatial redistribution of irrigated crops according to both their water efficiency and productivity are proposed with the aim of saving blue water for other purposes such as drought mitigation or environmental flows, among others. In particular, the proposed measures affect irrigated olive trees; the most widespread irrigated crop in this basin.