Search Results (166)

Urban agglomerations rely on both direct physical water intake and substantial virtual water embedded in cross-regional traded commodities and services to meet water demand. It is important to analyze the complex virtual water flows in urban agglomerations to advance sustainable water utilization and coordinated regional sustainable development. In this study, we constructed a multi-scale hierarchical analysis framework covering industrial sectors, internal cities and external hinterland regions by coupling multi-regional input–output (MRIO), ecological network analysis (ENA), and structural decomposition analysis (SDA). The framework was adopted to quantify consumption-driven virtual water flows across the Pearl River Delta (PRD) urban agglomeration in 2012, 2017 and 2022. Furthermore, we quantified the economic value of virtual water flows by considering water rights trading prices, which mainly reflect the scarcity value of regional water resources, aiming to provide new perspectives for water resources compensation and sustainable water management decision making. The results showed that the virtual water flows mainly satisfied food-related water requirements in the PRD. Declining water use intensity in external supply regions was the dominant factor reducing the water footprint in the PRD. The virtual water flows had greater economic value in the water-scarce northern provinces. On this basis, we put forward targeted financial subsidy recommendations for water-supplying external regions; the above economic quantification serves as the core evidence supporting this subsidy proposal. This work provides decision support for formulating sustainability-oriented water policies, balancing interregional water ecological benefits, and realizing long-term sustainable utilization of water resources. Full article

Under the dual constraints of global food security and ecological protection, conventional agriculture is hampered by low resource efficiency and sluggish environmental response. Crop digital twin technology establishes a dynamic virtual reality system that integrates crops, environment, and water to enable real-time interaction and optimization. Based on the existing literature, this paper reviews the concept, architecture, and core modules of this technology and summarizes its applications in precision irrigation and crop monitoring. There are three major bottlenecks that persist, including limited high-frequency multi-source sensing and spatiotemporal fusion, insufficient parameter calibration and dynamic updating, and weak cross-scale integration from plant to watershed. Water is increasingly recognized as the key constraint and control variable and acting as both the central physiological driver of crop growth and the mass-flow link that connects the soil–plant–atmosphere continuum. The spatiotemporal dynamics of crop water deficit, compensatory root water uptake, evapotranspiration feedback, and the hydraulic behavior of irrigation-district canal systems constitute the core hydrological processes that must be simulated within the digital twin. Synchronizing crop water demand, soil moisture dynamics, atmospheric evapotranspiration, and irrigation scheduling within a unified spatiotemporal framework establishes a complete sensing, diagnosis, prediction and regulation technical chain. This chain offers a core pathway for alleviating agricultural water scarcity, improving irrigation efficiency, and ensuring food security. Full article

The concept of virtual water is currently one of the most important issues in water resource management, especially in a context marked by structural water scarcity. Beyond the analysis of virtual water flows, which has been widely studied in the literature, this study aims to better understand the relationship between virtual water exports and economic growth. This paper analyzes the dynamic relationship between Morocco’s economic growth and agricultural virtual water exports to the European Union over the period of 1986–2023. An ARDL model was used based on annual data to test cointegration and estimate short- and long-term effects, controlling for gross fixed capital formation and agricultural value added. The bounds test confirms the existence of a stable long-term relationship between the variables. The results suggest that export specialization may be associated with foreign earnings and agricultural activity while also coinciding with greater pressure on resources and potential adaptation costs, especially for blue water resources. However, estimates indicate that in the long term, investment is positively and significantly associated with growth, while virtual water exports are associated with a negative effect on GDP, suggesting that export gains may be offset by increasing water constraints and sectoral trade-offs, and that agricultural value added mainly influences short-term dynamics. The results highlight the importance of integrating water footprint and virtual water trade concepts, as well as climate constraints, into agricultural and trade strategy planning while strengthening policies on water efficiency, innovation, and governance. Full article

This study presents a gate-to-gate life cycle assessment (LCA) of an industrial sweet cherry sorting and packing facility in Greece, directly addressing environmental sustainability in agri-food supply chains through data-driven impact quantification and improvement pathways in post-harvest operations. The assessment focuses on a gate-to-gate system boundary encompassing all processes inside the cherry sorting and packing facility, while upstream cherry production and downstream waste management are modeled and reported separately to provide system-level context. Core-stage hotspots are then analyzed in detail in the Results section, highlighting the dominant role of electricity use compared with packaging materials. The functional unit is defined as 1 kg of packed, market-ready cherries at the factory gate. Primary data are obtained from high-resolution, batch-level measurements of mass flows, energy use, water consumption, packaging materials and waste streams over a full processing season, structured as virtual sensor outputs. These sensor-informed operational data are combined with secondary life cycle inventory information from established databases to quantify climate change impacts and identify environmental hotspots across materials, energy, water, and waste, thereby delivering a quantified picture of environmental performance in the post-harvest stage. The results show that corrugated cardboard and associated packaging components are among the main contributors within the facility-level, gate-to-gate system, while the Core stage accounts for 28.43% of total GWP100. Upstream cherry production dominates the overall Upstream–Core–Downstream climate footprint with 70.61% of total impacts. Moreover, practical mitigation scenarios are modeled, including packaging optimization, partial substitution of grid electricity with photovoltaic generation, and increased water recirculation. Ιn the combined mitigation scenario, where packaging optimization, low-carbon electricity and improved water management are implemented simultaneously, total GWP100 decreases from 114,207.32 to 92,500.27 kg CO₂-eq (−19.0%) relative to the baseline, providing actionable sustainability improvements for industry stakeholders and supporting Sustainable Development Goals (SDGs) related to climate action and resource efficiency. In addition, the proposed virtual sensor architecture and data workflow support continuous monitoring, eco-efficiency management and near-real-time LCA implementation in post-harvest agri-food systems, enabling operational sustainability. Full article

Water scarcity in urban areas, pollution, and the growing interdependence of resources have led to the emergence of the urban water footprint (UWF) as a significant indicator of urban sustainability. However, research on the UWF has attracted considerable interest from the scientific community, given the methodological shortcomings that currently exist. This paper focuses on available studies on the UWF through a systematic literature review (SLR) using the Scopus and ScienceDirect databases. Following the PRISMA 2020 statement and the quality assessment framework developed by Kitchenham and Charters, a total of 61 studies were identified. The results reveal an increase in the number of studies on the UWF, particularly since 2016, focusing on specific cities where volumetric methods were used to calculate the blue or total water footprint. Other findings highlight changes in application objectives, particularly the shift from descriptive studies to prescriptive studies aimed at policy formulation, water efficiency, water governance, and the assessment of sustainability in urban systems from a water perspective. In summary, this research highlights significant gaps in multiscale and comparative studies, inconsistencies in system boundaries, and a lack of a socio-ecological perspective in the assessment of the UWF. Full article

Sediment accumulates behind dams, thereby reducing their operational efficiency. In response to this issue, hydraulic flushing is considered an effective solution for its removal. A numerical model is used to provide a deep understanding of this process and its dynamics. It acts as a low-cost virtual laboratory that eliminates the need for costly field experiments and provides a precise understanding of sedimentation and flushing behavior. This study used numerical modeling to examine sediment deposition in the Tigris River upstream of the Samarra Barrage. Within the iRIC framework, two models were used: NaysCUBE and Nays2DH. NaysCUBE is a three-dimensional solver that provides detailed simulations of partial gate openings and vertical flow distribution. This capability is crucial for a realistic analysis of the flushing process. Nays2DH is a two-dimensional solver that simulates full gate openings and captures general flow patterns. Results showed that sediment deposits were mostly concentrated within the first kilometer upstream of the dam, particularly when backwater effects caused the outflow to be lower than the inflow. Different gate operation schemes produced varied results: some configurations improved the balance between sediment movement and water flow, whereas others caused local erosion and uneven scouring. Results showed that lowering the water level at the barrage by 1 m increases shear stress on the riverbed by up to 25%, thereby improving the river’s ability to carry sediment without the need for additional discharge. High-discharge flushing operations are no longer feasible because of the reduced flow in the Tigris River since the operation of the Ilisu Dam in Turkey. This study recommends maintaining low water levels at the barrage with frequent and reasonable maintenance operations by partially opening the gates (40–60%). This strategy maintains a balance between the required water storage and sediment control, thereby ensuring the long-term sustainability of the hydraulic structure and the river ecosystem. Full article

Virtual reality (VR) is increasingly used as an interactive instructional medium in engineering education, yet evidence on practical implementation and student-reported experience remains limited. This study examined students’ perceived experience and usability across VR and traditional instruction within a crossover design in a UV-C water disinfection lesson. Using a mixed 2 × 2 crossover design, 52 undergraduate engineering students completed both a VR lesson (Meta Quest 3; Unreal Engine 5.4) and a content-aligned traditional session delivered with slides and a physical UV disinfection stand. After each session, participants reported perceived flow (short Flow Index) and engagement (adapted User Engagement Scale); the System Usability Scale (SUS) was completed after the VR session only. A brief knowledge quiz and open-ended feedback were also collected and used descriptively. Students reported higher perceived flow and engagement in the VR condition than in the traditional condition, and VR usability was generally rated acceptable-to-excellent, with higher SUS scores observed in the VR-first sequence than in the traditional-first sequence. Qualitative feedback emphasized clarity and interactivity, and most participants expressed a preference for a blended approach. Overall, the results support the practical feasibility and positive user acceptance of the VR lesson in this instructional context. The findings also suggest that perceived usability may be associated with instructional sequence, although this pattern should be interpreted cautiously within the perception-based scope of the study. Full article

Hybrid renewable energy systems (HRESs), mixing conventional and renewable power sources and occasionally storage units, have become the norm regarding electricity generation. Robust long-term planning of such systems requires stakeholders to test different layouts and system configurations, while their operational management relies on forecasting surpluses and deficits to achieve optimal decision making. However, both tasks, which in fact constitute a flow allocation problem across power networks, are subject to multiple peculiarities, arising from the nonlinear dynamics of the underlying processes, subject to numerous technical and operational constraints. Interestingly, a mutual problem emerges in water resource systems, also comprising network-type storage, abstraction and conveyance components. In this vein, triggered from well-established simulation approaches from the water domain, we introduce a generic (i.e., topology-free) and time-agnostic framework, the key methodological elements of which are: (a) the graph-based representation of the power fluxes; (b) the effective handling of energy uses and constraints through virtual nodes and edges; (c) the implementation of priorities via proper assignment of virtual costs across all graph components; and (d) the configuration of the overall problem as a network linear programming context, which allows the use of exceptionally fast solvers. Specific adjustments are required to address highly complex issues within HRESs, particularly the representation of conventional thermal and pumped-storage hydropower units, as well as the power losses across transmission lines. The modeling approach is stress-tested by means of configuring a hypothetical HRES in a non-interconnected Aegean island, i.e., Sifnos, Greece. Full article

Water scarcity is increasingly shaped by interactions between environmental constraints and interconnected economic systems, evolving from a localized supply–demand issue into a systemic risk embedded in economic networks. This study develops an integrated framework that conceptualizes water scarcity as a multidimensional risk by jointly accounting for water quantity, water quality, and environmental flow requirements, and embeds it within a multiregional input–output (MRIO) model to examine its formation and transmission across China. Results show that multidimensional constraints substantially amplify water scarcity risk and reshape its spatial distribution, extending risk beyond traditionally water-stressed regions to major agricultural provinces and key ecological function zones. Water-intensive, pollution-intensive, and basic industries form the core of risk accumulation, while virtual water linkages drive cross-regional risk propagation, with developed coastal provinces acting as major receivers. Network analysis identifies a small number of provinces—particularly Henan and Jiangsu—as critical hubs for risk transmission and systemic amplification. These findings highlight the need for integrated, multidimensional, and network-oriented water governance to enhance water system resilience. Full article

With the deepening of international trade and the increasing shortage of land resources, the importance of virtual soil trade in grain has become increasingly prominent. Based on FAO data, this study constructs the virtual soil trade network of wheat, rice, corn and soybean in the major G20 grain trading countries in 2013 and 2023, measures its network characteristics, and uses the exponential random graph model to explore its influencing factors from three dimensions of economic scale, geographical characteristics and resource endowment. The results show that: (1) virtual land trade is essentially a redistribution mechanism of land use pressure, rather than a simple grain flow; (2) the formation of network is driven by exogenous economic factors and endogenous relations; and (3) the role of each country in the network varies with the grain and food category and the development stage, showing a systematic differentiation. It is suggested that the allocation of land resources should be optimized according to the differences in virtual land flows in different countries and food categories. Since the export of virtual land is accompanied by ecological costs (such as deforestation, soil degradation, and water consumption), sustainability must be integrated into trade policies. Rations involve national security strategy, and it is necessary to strengthen domestic productivity and strategic reserves. Feed grain can use the market mechanism to promote trade liberalization and diversification, and reduce the risk of supply chain concentration while giving full play to the global comparative advantage. Full article

Water resources constitute a foundational strategic resource, and the efficiency of their spatial allocation profoundly impacts national sustainable development. This study integrates multi-regional input–output modeling, complex network analysis, and exploratory spatiotemporal data analysis methods to systematically examine the patterns, network structures, and spatiotemporal evolution characteristics of virtual water flows across 30 Chinese provinces from 2010 to 2023. Findings reveal the following: Virtual water flows underwent a three-stage evolution—“expansion–convergence–stabilization”—forming a “core–periphery” structure spatially: eastern coastal and North China urban clusters as input hubs, while East–Northeast–Northwest China served as primary output regions; The virtual water flow network progressively tightened and segmented, evidenced by increased network density, shorter average path lengths, and enhanced clustering coefficients and transitivity. PageRank analysis reveals significant Matthew effects and structural lock-in within the network; LISA time paths indicate stable spatial structures in most provinces, yet dynamic characteristics are prominent in node provinces like Guangdong and Jiangsu. Spatiotemporal transition analysis further demonstrates high overall system resilience (Type₀ transitions accounting for 47%), while abrupt transitions in provinces like Hebei and Liaoning are closely associated with national strategies and industrial restructuring. This study provides theoretical and empirical support for establishing a coordinated allocation mechanism between physical and virtual water resources and formulating differentiated regional water governance policies. Full article

Freshwater scarcity increasingly constrains agricultural sustainability and global food security, particularly where crop production and trade shape national water balances. This study quantifies Ecuador’s green (soil moisture/rainfall) and blue (surface and groundwater) virtual water flows associated with seven strategic crops (banana, cocoa, pineapple, maize, rice, barley and potato) from 2000 to 2023 using the Hoekstra–Mekonnen accounting framework, and FAOSTAT production and bilateral trade data. Furthermore, Logarithmic Mean Divisia Index (LMDI) decomposition analysis was applied to identify the key drivers influencing virtual water trade, including economic growth, population, product structure, and water intensity. Results reveal that Ecuador operates as a persistent net exporter of virtual water, with export flows dominated by green water, reflecting the country’s reliance on rainfall-supported production. Virtual water exports increased from 3000 to >15,000 Mm³·yr⁻¹ over the study period, while imports remained substantially smaller, confirming Ecuador’s structurally export-oriented agricultural economy. The LMDI outcomes show that export growth is driven primarily by economic expansion (8.28 × 10⁸ m³) and shifts in the crop export mix, partially offset by improvements in water intensity. These findings highlight Ecuador’s vulnerability to trade-related water pressures and demonstrate the value of virtual water indicators for guiding water governance and SDG-aligned trade strategies, thereby promoting the decoupling of economic growth from water resource consumption and connecting virtual water trade to domestic water scarcity. Full article

As a key element in maintaining ecological balance and ensuring human survival and development, the accounting of water resource assets is a fundamental prerequisite for the preparation of natural resource balance sheets. To achieve regional water resource balance and promote high-quality, coordinated socio-economic development, this study is grounded in the cyclical evolution of water resource assets and the concept of water-ecology-economy coupling. A classification method, which integrates physical water resources and virtual water resources, is proposed to define the accounting boundaries of water resource assets. Additionally, a multi-dimensional accounting model is developed that integrates the flows of physical and virtual water, allowing for a systematic assessment of the stock and flow characteristics of water resource assets within an area of 2.0523 million square kilometers across 11 provinces and municipalities in the Yangtze River Economic Belt. It is concluded that the top six water resource assets in the Yangtze River Economic Belt are concentrated in the middle and lower reaches of the river, and the proportion of virtual water in the southwestern provinces is less than 26%, among other significant regional differences in water resource assets. The findings aim to clarify the value transformation pathways of composite water resources, enhance the methodological system of water resource accounting, and provide a scientific basis for informed decision-making regarding optimal water resource allocation within the basin. Full article

Under the spatial distribution of water resources, with more water resources in the southern regions and less in the northern regions, and the “north–south grain transport” pattern, calculating the virtual water flow in food trade between provinces in China and analyzing its sustainability is crucial for ensuring the country’s water resources and food security. By considering various products and consumption types, the virtual water flow in inter-provincial grain trade is estimated using the Minimum Transport Cost Method and the Penman-Monteith formula. The sustainability of this virtual water flow is evaluated at the provincial level. (1) The results show that the top three provinces with the largest net virtual water outflow from inter-provincial grain trade are Heilongjiang, Henan, and Anhui, with net outflows of 43.166 billion m³, 18.974 billion m³, and 13.089 billion m³, respectively. The top three provinces with the largest net virtual water inflows are Hebei, Guangxi, and Liaoning, with net inflows of 18.875 billion m³, 10.076 billion m³, and 8.795 billion m³, respectively. (2) The largest inter-provincial virtual water flow occurs from Henan to Hebei (15.06 billion m³), followed by Inner Mongolia to Hunan (9.57 billion m³), and Heilongjiang to Hubei (9.04 billion m³). (3) Overall, the current pattern of virtual water flow in China’s grain trade is sustainable, though several exporting provinces are under greater stress. In the actual scenario, the average water resource pressure index across all provinces is 0.43, 17.31% lower than the average of 0.52 in the scenario without inter-provincial grain trade. Compared with the scenario without inter-provincial grain product trade, in the actual scenario, Heilongjiang, Jilin, and Inner Mongolia show a higher increase in water resource pressure index, with increases of 94.74%, 73.68%, and 48%, respectively; Beijing, Shanghai, and Qinghai show a greater decrease in water resource pressure index, with reductions of 94.64%, 79.41%, and 66.67%, individually. And then, efforts should be made to adjust and optimize the structure of grain production and circulation; provinces with virtual water net outflow (such as Heilongjiang, Henan, Anhui, etc.) need to adjust their grain cultivation types and grain export structures.; provinces with virtual water net inflow (such as Hebei, Guangxi, Liaoning, etc.) can appropriately expand the scale of grain cultivation, while adjusting their diets to reduce the demand for water-intensive grains. Full article

The present research moves the focus from merely describing epikarst flow to quantifying its natural filtration performance and contaminant retention mechanisms through integrating in situ tracer experiments with controlled laboratory modelling—an approach seldom applied in previous studies. Two field experiments at Peč Cave demonstrated that the epikarst exhibits rapid hydraulic connectivity—evidenced by fast tracer breakthrough with virtual flow speeds between 0.0041 and 0.006 m/s—yet simultaneously provides strong attenuation, as shown by the low tracer recovery and near-complete removal of microbial contaminants as well as nitrogen compounds through retention, degradation, and dilution under natural infiltration conditions, including rainfall and snowmelt. Complementary laboratory simulations further confirmed this duality, with nitrate concentrations reduced by 30–50%. Field data and lab results consistently indicated that the epikarst does not merely transmit water but actively adsorbs and transforms pollutants. Overall, the epikarst on Suva Planina functions as an effective natural filtration layer that substantially improves groundwater quality before it reaches major karst springs, acting as a protective yet vulnerable “skin” of the aquifer. These findings highlight the epikarst’s critical role in Suva planina Mt. karst aquifer protection and results support consideration of epikarst in groundwater management strategies, particularly in regions where springs are used for public water supply. Full article