Investigating the influence of spatial and temporal resolutions in water footprint assessment on blue water scarcity index in Iran

Iran, is amongst the arid and semi-arid regions of the world, suffering from blue water scarcity. Hence, sustainable development in Iran requires modifying blue water consumption pattern, and on the other hand, all water resources consumption planning requires a proper knowledge about the water scarcity status in different regions of the country. In this study, for the first time, water scarcity status is assessed based on the blue water scarcity index (BWS) under different temporal resolutions, including annual and monthly scales, and different spatial resolutions, including national, climate-regions, and provincial scales. In this regard, total blue water consumption was first estimated on a daily basis for different provinces over the period 2005-2015, and then was divided by blue water availability to estimate BWS. A BWS indicate, low, moderate, and severe water scarcity, respectively. Every place or any time scale with BWS> is called a hotspot. Based on the annual assessment for the entire country 46% of total blue water consumption in the agricultural sector is unsustainable, and is consumed at the cost of violating environmental flow requirements; under such conditions, the BWS is 1.9 and the entire country is under moderate water scarcity. However, based on the annual assessments at finer spatial resolutions, the humid climatic region and 7 provinces do not experience blue water scarcity. Besides, there are non-hotspots for all considered spatial scales under monthly assessments. Based on the findings of this study, changing the resolution of the BWS assessments will change the number of hotspots in the range of 1 to 37, and will change the status of these hotspots as well. Hence, properly diagnosing the actual hotspots, in which environmental flow requirements are not satisfied due to unsustainable blue water consumption, requires assessments at the possible finest spatial and temporal scales.