Virtual water flow and water footprint as optimizer of water resource management in the state of Ceará, Brazil

The water exported indirectly by sending products to other countries, or vice versa, is called a virtual water flow and this can be measured through water footprint (WF) calculations, which represent the embedded water needed to manufacture a product. This present study aims to analyze the virtual water flow and the WF of the main products exported by municipalities in the state of Ceará in the year 2019, in order to enhance the management of the state’s water resources. Analytical hierarchy process (AHP), the most commonly used multicriteria decision-making method in the world, was used to determine which product is more sustainably produced by the municipalities of Ceará, with the criteria: WF, price, and volume exported. The alternatives are at least two of the seven categories of products exported by the state where the “fruit or vegetable juices” class was preferred as the most sustainable. It was found that most cities in the state that export agricultural products use only one basin, which can lead to very low reservoir levels, while the other hydrographic basins in the state are underused. It is worth noting that the Metropolitan Basin concentrates on 11 out of 32 municipalities that export abroad and that it is responsible for supplying more than 4,074,730 inhabitants, according to Brazilian Institute of Geography and Statistics (IBGE, 2019).

Water-Saving Efficiency and Inequality of Virtual Water Trade in China

Virtual water trade is widely considered as a potential method to solve local water shortage and unequal distribution. However, limited research investigated water-saving efficiency and water inequality of inter-provincial virtual water trade. In this study, we sought to explore this issue within China based on the 2015 input-output data. A multi-regional input-output model and a modified input-output model were used to estimate the virtual water trade and its impact on water-saving and water inequality. Our results suggest that: (1) The total virtual water flow across the country is 200.03 × 109 m3, which accounts for 32.77% of water withdrawal. The agriculture sector contributes the highest proportion (73.99%) to virtual water flow. (2) Virtual water trade could decrease water withdrawal by 446.08 × 109 m3 compared with withdrawal under no-trade situation at a national level, and 22 provinces could gain benefits through inter-provincial trade with a positive water-saving efficiency index. (3) Virtual water trade also causes water inequality, which exacerbates water scarcity of exported provinces, especially in northwest provinces. (4) There is a conflict between water conservation and water inequality, but different provinces show significant heterogeneity.

Analysis of Virtual Water Trade Flow and Driving Factors in the European Union

The inefficient application of water resources has become an urgent problem restricting the world’s sustainable development. Virtual Water Trade opens a new perspective on improving water resource utilization efficiency. Based on a multi-regional input–output model and the logarithmic mean Divisia index, the virtual water flows between 2000–2014 in 43 countries and regions have been evaluated, and the driving forces of changes in virtual water flows for the European Union were revealed. During the study period, the total amount of virtual water flow continued to increase. The United Kingdom is a net virtual water importer that depends on the European Union significantly. There was a large amount of virtual water flow from the European Union to the United States during 2000–2012. However, China gradually seized the share of virtual water from European Union exports after 2012. Economic effects and virtual water intensity effects are the most significant drivers of virtual water flows. The difference is that the economic effect positively drives virtual water flows, while the virtual water intensity effect negatively influences. The results reveal the nature of the United Kingdom in the virtual water trade and can provide post-Brexit recommendations.

Virtual Water Trade in the Service Sector: China’s Inbound Tourism as a Case Study

Research on virtual water and the water footprint is mainly focused on agriculture and industry, and less so on the service sector. The trade in products generates virtual water flow, as does the flow of people. The flow of international tourists will inevitably lead to the transfer and exchange of water resources embedded in the virtual form. This study takes China’s inbound tourism flow as the research object, from the perspective of the water footprint, in order to explore virtual water “exports” to the world. Based on kernel density estimation and ArcGIS spatial analysis, spatial-temporal evolution and structural difference were investigated. Virtual water “exports” showed an increasing trend. The kernel density estimation curves basically exhibited a “single peak” feature which indicated that virtual water “exports” from tourism were not significantly polarized in China. In terms of spatial evolution, this varied greatly at the provincial and regional level and Guangdong was always in the high value area. The south displayed greater values than the north, but this difference in provinces narrowed over the years. The water footprint of food was the largest, more specifically, the green component of this water footprint. Promoting a reasonable diet, reducing food waste, improving agricultural production technology, reducing the frequency of changing hotel supplies, and encouraging the use of new energy helped to reduce the water footprint. Virtual water trade in the service sector provides a new idea for helping to mitigate the global water crisis, in addition to virtual water flow for agricultural products.