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Agriculture is a key sector and a major consumer of water resources; therefore, a clear understanding of the agricultural water demand for crop production and consumption is imperative for addressing water scarcity problems, particularly in water export regions. This study provides new insights into the influential factors driving the changes in the agricultural production water footprint (WFprod) and consumption water footprint (WFcon) in the net water import and net water export regions. The WFprod and WFcon of wheat are evaluated in Beijing city (the net water import region) and Heilongjiang province (the net water export region) over the period 1996–2015. The statistical significances of the influential factors, i.e., climate change, gross domestic product, population, dietary demand and technology update are determined using a multivariate linear regression model (LRM) and nonlinear regression model (NLRM). The results indicate that the gross domestic product and population were the dominant positive influential factors, whereas technology update and dietary demand were the dominant negative influential factors affecting the changes in the WFprod and WFcon in the net water import region. In the net water export region, technology update was the dominant negative influential factor affecting the changes in the WFprod and WFcon. Climate change did not contribute significantly to the changes in the WFprod and WFcon of wheat; however, it was an important factor (especially precipitation for the green WF with an average relative importance of more than 22% and the blue WF with an average relative importance of more than 15%) affecting the changes in the WFprod and WFcon of the crop. An in-depth analysis of the influential factors that contribute to the changes in the WFs is fundamentally important for decision-makers to develop countermeasures and strategic planning implementations to mitigate water resource pressure in China.

Massive amounts of water and land embodied in crops are transferred via food trade. This study established a network-based framework for the water–land nexus in food trade to investigate the spatial linkages of water, land, and food. Based on the gravity model and linear programming optimization, the food trade model was first built to simulate crop trade. Then water consumption and land use for various crops in different regions were inventoried to establish the food-related virtual water network and food-related virtual land network. Grey water related to water quality, blue and green water related to water quantity, were incorporated into the food-related virtual water accounting framework to identify the role of food trade in the spatial reallocation of water. Similarly, the food-related virtual land network was built based on the land use for different crops and the food trade model. Finally, a case study was conducted using ecological network analysis to analyze the properties and connections within the food-related virtual water/land networks of China. The results showed that the green and grey water consumption associated with food production, the effects of which have previously been neglected, account for a huge proportion of the total water consumption, especially in water-scarce provinces. The controllers/dependents in the networks that have strong control relationships with other provinces were identified. The proposed network-based framework for the water–land nexus may help boost synergies associated with spatial reallocation of water and land via food trade and explore pathways for sustainable management of water, land, and food resources.

The irrational virtual water flow caused by grain trade makes water use efficiency low and further threatens grain security in China. However, optimizing the grain virtual water trade flow from the perspective of the economic value of water resources has rarely been carried out in current research. This paper proposes a linear optimization model considering opportunity cost to fill this gap. The current situation of grain virtual water trade is analyzed and we find an irrational trade mode which quantity and direction of grain virtual water trade in some provinces are not consistent with actual demand. Then, opportunity cost is added to the linear optimization model to adjust grain virtual water trade which shows several advantages compared to general linear optimization model. Results show that huge virtual flow is generated, up to 1179.24 billion cubic meters of water. And the economic value generated by grain virtual water trade can not only cover the transportation cost but can also eventually generate economic benefits of 7410 billion yuan. Finally, the relevant conclusions and implications of adjusting China’s grain virtual water trade are obtained.

The mitigation of water stress in crop production is important for relieving the growing global water shortage. The water footprint scarcity (WFS) for regional water stress evaluation integrating blue and green water resources and the water footprint of the crop production industry were developed in this paper. Three subregions in China, industry-based southern Jiangsu (SJS), agriculture-based northern Jiangsu (NJS) and middle-type central Jiangsu (CJS), were selected to study the spatiotemporal pattern and driving mechanism of WFS. The results show that green water accounts for 56.6% and 71.8% of agricultural water resources available (AWA) and crop water footprint (CWF) of Jiangsu Province. The WFS of Jiangsu was calculated to be 2.26, and almost all prefectures for every year from 1996 to 2015 faced very high water stress (WFS > 1.20). The WFS value increased in NJS and CJS and decreased in SJS over time; meteorological and social factors affected the WFS at the same time. Land irrigation was the main factor to explain the growing water stress in the agriculture-based NJS. The WFS revealed the water shortage more clearly, especially in the water-poor agriculture-based areas, than the results of the conventional water stress index. The strategies for environmental change adaptation suggested by this study are to use WFS for agricultural water suitability evaluation and water resource management policy formulation; to reduce WFS through irrigation efficiency and crop variety promotion worldwide; and to implement compensation measures for agricultural products and virtual water trade to help underdeveloped agricultural production areas improve their agricultural production technology and control irrigation expansion.

At present stage, there is increasingly desperate contradiction in China’s water supply and demand. Importing virtual water by the import of agricultural products (industrial products) from other countries may be a possible way to alleviate it. Based on the Input-Output Table and relevant data in using water resources, this paper accounts China’s virtual water trade volume in 2012 systematically and does a research on industrial linkage effect of China. Results show that: (1) There is a net export of virtual water in China in 2012, while there is a large amount of net import of virtual water in agriculture. (2) The linkage between agriculture and the other industries has great influence on both imports and exports volume of china’s virtual water. After extraction, the virtual water imports volume only accounts for 66.33% of that before extraction; at the same time, the virtual water exports volume only account for 49.00% of that before extraction. Among them, the linkage effect between food production and tobacco processing industry and agriculture is the largest. The result shows that there is a certain degree of failure of virtual water trade strategy to relieve the contradiction of supply and demand of water resources through the virtual water net imports. Therefore, it is necessary to expand agricultural imports appropriately which requires more water consumption and moderately reduce agricultural exports. At the same time, we should consider the linkage effect between agriculture and other industries, and synchronously adjust the import and export of other industries, especially the food production and tobacco processing industry.

In this paper we draw on a unique dataset of hydrological and microbiological time series to apply water footprint (WF) methodology to quantify the environmental impact of cattle grazing on karst area in a regional park of the southern Apennines (Italy). The use of WF methodology in the same specific environment where relevant data are monitored, and the hydrogeological and microbiological characterisation of the study area, validate the results of our WF assessment, that can be summarised as follows. First, we show that an ecological indicator such as the grey water footprint (GWF) may be of particular relevance to the park authority to implement policies to preserve groundwater quality. Second, we introduce a new metric, referred to as the environment-related grey water footprint (GWFenv), to estimate the virtual water needed to absorb the microbial pollution of a cattle grazing process.

The improvement of the sustainability of global food systems is a top priority. Many efforts have targeted the production side, yet managing food consumption demand, i.e., people’s eating habits, might deliver important co-benefits from a land, water, and energy perspective. This paper focuses on assessing the water-related implications of food consumption and waste among Spanish consumers to discern possible policy recommendations. Specifically, we estimated the water footprint (WF) of the diet and associated food waste of Spanish households from October 2014 to September 2015, broken down by WF component (green, blue and grey) and its geographical origin. Our results showed that, for the analyzed period, the WF of food consumption in Spain is 52,933 hm3, equivalent to 3302 liters per person and day. The consumptive fraction (green + blue water) of this diet-related WF accounts for 89%, while the remaining 11% (127 m3 per person/year) is attributed to water quality impacts (grey water). The products that account for the largest share in the total WF are meat, fish and animal fats (26%) and dairy products (21%). Likewise, roughly 41% of the total WF linked to household diets is foreign, i.e., imported virtual water, and the main countries of origin are Tunisia, Portugal, and France. The WF of food waste accounts for 2095 hm3, equivalent to 131 liters per person and day. From a policy perspective, several studies have highlighted that high water savings can be achieved by reducing food waste; in Spain, however, eliminating food waste at household level would reduce the Spanish food-related WF by only 4% (292 hm3 of blue water and 1555 hm3 of green water). In the light of these results, a shift back to a Mediterranean diet, in which fruits and vegetables account for a larger share of the food intake, would deliver greater water savings.

Many modern cities have strongly invested in the sustainability of their urban water management system. Nordic cities like Stockholm or Copenhagen are amongst pioneers in investments towards integrated urban water management. However, cities can never be fully self-sufficient due to their dependency on external (water) resources. In this paper, we quantify this water dependency with respect to food consumption in nine cities located in the five Nordic countries (Sweden, Denmark, Finland, Norway and Iceland), by means of the water footprint concept. Detailed urban water footprint assessments are scarce in the literature. By analysing national nutrition surveys, we find that urban food intake behaviour differs from national food intake behaviour. In large Nordic cities people eat generally less potatoes, milk products (without cheese), meat and animal fats and they drink less coffee than outside city borders. On the other hand, they generally eat more vegetables and vegetable oils and they drink more tea and alcoholic beverages. This leads consistently – for the six large Nordic cities Stockholm, Malmo, Copenhagen, Helsinki, Oslo and Reykjavik – to slightly smaller food related urban water footprints (−2 to −6%) than national average values. We also analyse the water footprint for different diets based upon Nordic Nutrition Recommendations (NNR) for these cities. We assessed three healthy diet scenarios: 1) including meat (HEALTHY-MEAT), 2) pesco-vegetarian (HEALTHY-PESCO-VEG) and 3) vegetarian (HEALTHY-VEG). This shows that Nordic urban dwellers 1) eat too many animal products (red meat, milk and milk products) and sugar and drink too much alcohol and 2) they eat not enough vegetables, fruit and products from the group pulses, nuts and oilcrops. Their overall energy and protein intake is too high. A shift to a healthy diet with recommended energy and protein intake reduces the urban WF related to food consumption substantially. A shift to HEALTHY-MEAT results in a reduction of −9 to −24%, for HEALTHY-PESCO-VEG the reduction is −29 to −37%, for HEALTHY-VEG the reduction is −36 to −44%. In other words, Nordic urban dwellers can save a lot of water by shifting to a healthy diet.

Water shortages and the uneven distribution of water resources restrict China’s sustainable development. The concepts of virtual water and water footprints provide a new approach to alleviate regional shortages of Chinese water resources by the inter-provincial allocation of commercial water resources. In this study, an interregional input-output model was applied to quantitatively estimate the water footprint of each province in China and to quantify the inter-provincial transfer of virtual water. The results indicated that there was considerable diversity in the water footprints of the various provinces. Provinces with larger populations and greater GDP had larger water footprints, and developed regions had higher proportions of external water footprints. From the perspective of final demand, local consumption was the main factor driving the water footprints of these provinces. From the perspective of sectoral structure, the agricultural water footprint had a larger proportion in these provinces. The transfer of virtual water in China did not occur from regions with abundant water resources to those suffering from water shortages, but it generally occurred from west to east, from inland to coastal areas, and from underdeveloped to developed regions. Many water-deficient regions also had large net virtual water exports. Water shortages in China will be alleviated by the enhancement of industrial water-use efficiency in water-deficient regions, the transfer of water-intensive industries to regions with abundant water resources, and the development of tertiary industries with low water consumption.

The issue of growing water scarcity has been increasingly perceived as a global systemic risk. To solve it, an integrated approach considering different perspectives of water scarcity is at a premise. In this study, we developed an approach to calculate the blue water scarcity (BWS) and integrated the production, consumption, and water transfer perspectives into a single framework. The results are as follows: The average BWS in the Hetao irrigation district was 0.491 during the 2001–2010 year period, which was much larger than the threshold of 0.30, indicating a high water stress level. From the production perspective, the agricultural sector was the largest contributor to regional water scarcity and the average BWS was as high as 0.479. From the consumption perspective, BWS related to virtual water export was much larger than that related to water consumption for making products to be consumed locally and the values were 0.422 and 0.069, respectively. Under the influence of physical and virtual water transfer, BWS changed from 0.242 (medium to high water stress level) to 0.491 (high water stress level). Strategies for reducing agricultural water consumption, such as increasing crop water productivity, improving irrigation efficiency, and promoting more reasonable irrigation water price, could be adopted in the Hetao irrigation district to alleviate regional BWS. Compared with physical and virtual water import, the virtual water export played a more important role in influencing the regional water scarcity, and the increase in crop water productivity, decrease in crop export volume, or adjustment of trade pattern from water-intensive crops to water-extensive ones could be feasible measures to decrease virtual water export for lower water stress, while the trade-offs in the product-consuming regions should be considered.

The disjunction of ecological and socioeconomic sciences is one of the main obstructions in current human–natural integrated systems research. Therefore, gridded GIS technology is introduced in an attempt to achieve the spatial flow analysis of water pollution in eco-natural systems. With this unified GIS platform, an input–output table and one-dimensional water quality model are chosen to manifest the spatial economic flows and spatial natural flows of water pollution separately. Finally, the comprehensive effect of the spatial circulation of water pollution in eco-natural systems is assessed. A case study of the framework is carried out in the Changzhou District of Taihu Lake, China, and the main results show the following: (1) COD (chemical oxygen demand) direct emissions represent the characteristics of high intensity and clustering in industrial regions; control unit 8 is the largest secondary emissions unit, representing up to 41.79% of the total, whereas the emissions of the primary industry tend to be low intensity and widespread. (2) The gray virtual water flow from the primary industry to other heavy industries (except the chemical industry) is the main flow type; the transfer amount adds up to 2512 t, and the inter-units with the largest occupation of water environment capacity (WEC) upstream to downstream are 8–9, nearly up to 1548 t. (3) Under the interaction of positive and negative functions of economic flows and natural flows, the final effect of pollution transfer may be offset, environmental degradation or environmental improvement. This study could provide a basis for ecological compensation, environmental exteriority and optimization of industrial structure layouts.

The virtual water concept has received significant attention through manifesting the role of human activities such as consumption and international trade on water resources. However, few studies have focused on how the interactions of local supply chain exert impact on local water resources associated with virtual water flows. In this study, we introduce an indicator which is attached to the virtual water concept, termed the “internal water use of products” (IWUP), to examine the direct and indirect water use from local water supply for goods and services in Beijing for the years 1997, 2000, 2002, 2007, and 2010. This indicator links the pressure on local water resources to the final products with sectoral details, highlighting the importance of economic analysis in local water resource management. A structural decomposition analysis revealed that the increase in economic water productivity would have caused Beijing's IWUP to decrease by 196% from 1997 to 2010, if other determining factors remained constant. Such great efficiency improvements have allowed Beijing to fulfill its objectives of economic growth, whilst in the meantime reducing the water used in production. However, we also found that production structure adjustment would increase the IWUP, mainly due to a shift from agricultural and industrial sectors to service sectors.

China has experienced rapid economic development during the recent years. In the meantime, the total water use in China has greatly increased, causing considerably severe water shortage. To quantify how the social-economic development drives the change of water use is of great importance for Chinese government. This study aims to quantitatively investigate the determinants of the growing water use in China during 1997–2007. China's water usages in 1997–2007 are indicated by the Internal Water Footprint (IWF), External Water Footprint (EWF), and Exported Virtual Water (ExVW) using an input–output based WF analysis. A dynamic Structural Decomposition Analysis (SDA) model is employed to decompose the changes in the total WFs (TWF) into five social-economic determinants. The dynamic SDA model, which uses a nonlinear path function to simulate the real paths followed by determinants, is a further development of a path-based SDA algorithm. To validate the dynamic SDA, a comparison study is carried out against the commonly used mean decomposition model. The results from the WF analysis show that, during 1997–2007, the increase of China's water use is dominated by the ExVW, which increases significantly due to the expansion of exports. While the changes in the IWF and EWF tend to help mitigating the water pressure. The dynamic decomposition results indicate that the consumption level is the dominant factor of China's water use growth, and the changes in water-saving technology and final demand pattern contribute largely to offsetting the water use growth. The model comparison shows that the dynamic SDA model is more advanced in obtaining reliable results and addressing the static issue of traditional SDA models. This study provides a robust framework for understanding the water use situation from the social-economic perspectives, which benefits sustainable water management.

Rapid urbanization has challenged the utilization and the circulation of water, especially in rapidly developing regions. It is necessary to disaggregate virtual water metabolic networks (VWMN) in representative areas, and examine their relevant dynamics to sustain regional development. In this study, the VWMN of Guangdong Province, China is developed to explore the ecological relationships between pairwise components and identify the ecological hierarchy structure of VWMN. Particularly, the structural analysis of VWMN is optimized and two indicators are proposed in this study. The integral virtual water recycling index (IVWRI) enable to reveal the extent that components are benefited from the existence of the VWEN and the integral virtual water productivity (IVWP) can identify economic output per unit integral virtual water utilization of each component. The results indicate that the tertiary industry fails to promote the development of its upstream industries, and the integral virtual water productivity of this industry is declining. Technology upgrading of manufacturing industry and steady import of primary products are imperative. Moreover, petroleum, coking, nuclear-fuel and construction industries are key components that clog the studied VWMN. This research provides scientific support for the robust development of VWMN, particularly in alleviating water scarcity and promoting sustainable regional development.

In the context of social responsibility and, of the directives aimed at an integral management of natural resources, the Water Footprint (WF) has been widely spread as an indicator that contributes to a safe and sustainable use of water. The purpose of this study was to determine the WF for rice production (WF R ) in two rice-growing areas in Argentina: central-east Entre Rios and Santa Fe. The calculation was made using the methodology proposed in The Water Footprint Assessment Manual , according to which the WF of a crop, in this case rice, represents the relation between the amount of water satisfying the evapotranspiration demand (CWU) and the field productivity. The WF has three components: green (WF green ), associated with rain used by the crop (CWU green ); blue (WF blue ), related to underground or surface water that fulfils the evapotranspiration demand (CWU blue ); and grey (WF grey ), related to the volume of water required to dilute the residues of pollutants generated from the crop production. To estimate the CWU blue and CWU green , a rice water balance model (RWM), specifically developed for continuous flooding irrigation, was applied. Based on daily data of precipitation, crop evapotranspiration and soil variables the model allows calculating gross irrigation depth, surface runoff due to precipitations, variation of water stored in the soil, and deep percolation. Four agricultural seasons were assessed: 2009/2010, 2010/2011, 2011/2012, and 2012/2013. In Entre Rios, WF was 987 m 3 ton −1 (44% WF green and 56% WF blue ), whereas in Santa Fe it was 846 m 3 ton −1 (36% WF green and 64% WF blue ). In accordance with related work in the region, WF grey was not considered. Although only CWU is part of the WF calculation, the other components of the water balance are necessary for rice production. The RWM model determined the consumptive use of the crop and distinguished blue water from green water, besides calculating the other parameters of the water balance. This made possible to show the inefficiencies in the system since precipitations are not fully used. The WF R , together with these components, is useful to make comparisons between different regions and it is a tool to promote water saving, provided that it is complemented with specific policies, such as the differential application of irrigation taxes or electric power rates.

Substantial amount of world’s population experiences severe water scarcity problems. The water scarcity related threats on food security, human health and natural ecosystem are estimated to increase in the future, due to unconscious use and overutilization of water resources. Water footprint assessment studies at basin level are very important and provide a key role for sustainable development of freshwater resources especially in arid and semi-arid regions. However, comprehensive studies on water footprint assessment of river basins are quite limited due to requirement of wide-range of statistical data. The main scope of this study is to analyze the blue and green water footprint of Upper Tigris River Basin (UTRB, Turkey) with a bottom-up approach for the years between 2010 and 2018. Water footprints of agricultural production, livestock production and industrial plus domestic water use have been separately studied. Total blue and green water footprints, per capita water footprints and virtual water contents of the major crops harvested in the UTRB were calculated and compared with surrounding countries. A sustainability assessment based on the scarcity indicators has also been provided. Annual water footprint of UTRB is calculated as 7.2 Gm3/yr for the specified time interval corresponding 1748 m3/cap/yr. Crop production has the highest share with 79% of total water footprint. Wheat is the primary crop cultivated in the study area and responsible for 45% of consumptive water use of all crops. The livestock and domestic plus industrial water footprint were obtained as 16% and 5% of the complete basin’s water footprint, respectively. Annual blue water scarcity of the basin is obtained to be 87% which is classified as low scarcity. The findings of this study are expected to increase water allocation efficiency and sustainability of the study area. It is also expected to contribute the integrated basin management studies and cooperation between riparian countries for better planning and management of transboundary water resources.

This study investigates the virtual water profile of the world in 2004 based on a multi-region input–output model. The water footprints of 112 nation-level regions are calculated and the footprint compositions of major water consumers are analyzed. Less than 35% of the global virtual water requirement is provided by agricultural products, in spite of the fact that 69% of the total water withdrawal is associated with agricultural sector. At the national scale, India, the United States, and mainland China are the world's largest virtual water consumers. Per capita water footprint varies from 30 m 3 for Rest of South Central Africa to 3290 m 3 for Luxembourg. As one of the major determinants of national footprint, international virtual water trade sums up to 30% of the direct water withdrawal of the world. Meanwhile, results show that 57% of the international virtual water flows is embodied in non-food trade, confirming the importance to take not only food product but also non-food product into account when overall water budget is considered. Mainland China is the world's leading exporter and deficit receiver in terms of virtual water trade (204 Gm 3 and 142 Gm 3 , respectively), in contrast to the United States as the leading importer (178 Gm 3 ) and Japan as the leading surplus receiver (77 Gm 3 ). Finally, the virtual water trade connections of China and the United States with their major trading partners are revealed via introducing the index of virtual water dependency. Results presented in this study are of essential implications for policy making regarding water using pattern adjustment and water security enhancement.