Cross-sectoral implications of the implementation of irrigation water use efficiency policies in Spain: A nexus footprint approach

Resumen

One technical solution often suggested for alleviating water scarcity is to increase the efficiency of irrigation water use. In Spain, several plans have been launched since 2000 to upgrade irrigation infrastructures and thereby achieve water savings equivalent to 2500 hm(3)/year and promote rural development. The present study uses a footprint approach to evaluate the impacts on land, water, energy, and carbon emissions of the implementation of irrigation modernization policies in agriculture in Spain between 2005 and 2011. The results show that during the period studied, the irrigated area remained stable (+0.3%), although there was a shift in crop patterns, with low-value non-permanent crops being replaced by high-value permanent crops. The water demand for irrigation decreased by 21%; half of this is explained by the shift in crop patterns and the reduction of the consumptive fraction (i.e., blue water footprint), and the other half by the cutback of return flows associated with the higher efficiency of the irrigation infrastructure. Changes in water demand have been accompanied by a progressive substitution of surface water for groundwater. Reduced water demand for irrigation has brought a reduction of 13% in water's energy footprint and 25% in its carbon footprint. In relative terms, water efficiency (m(3) consumed/m(3) irrigated) has increased by 8%, although this has also increased the energy intensity (kWh/m(3)) to 9%. The emission rate (kgCO(2) equiv/m(3) irrigated) has decreased by 12% as a result of the drop in the emission factor of electricity production. Overall, irrigation modernization policies in Spain have supported the transition from an irrigation sector that is less technified and heavily dependent on surface water into one that is more productive and groundwater-based. From a resource-use perspective, such transition has contributed to stabilizing or even decreasing the irrigated land, and surpass the annual water savings target of 2500 hm(3), although it has also made the sector more energy-dependent. Despite the overall positive outcomes, the observed water savings are masked by various synergistic factors, including favorable climatological conditions toward the end of the study period, which contributed strongly to curbing overall irrigation water demand. In the light of the higher frequency of observed droughts in Spain, the investments done so far do not guarantee that the planned water saving targets can be sustained if not complemented with additional measures like restricting irrigated area and/or setting caps for water intensive crops.