We present a network model of interstate food trade and report comprehensive estimates of embodied irrigation energy and greenhouse gas (GHG) emissions in virtual water trade for the United States (U.S.). We consider trade of 29 food commodities including 14 grains and livestock products between 51 states. A total of 643 million tons of food with a corresponding 322 billion m³ of virtual water, 584 billion MJ of embodied irrigation energy, and 42 billion kg CO₂-equivalent GHG emissions were traded across the U.S. in 2012. The estimated embodied GHG emissions in irrigation water are similar to CO₂ emissions from the U.S. cement industry, highlighting the importance of reducing environmental impacts of irrigation. While animal-based commodities represented 12% of food trade, they accounted for 38% of the embodied energy and GHG emissions from virtual irrigation water transfers due to the high irrigation embodied energy and emissions intensity of animal-based products. From a network perspective, the food trade network is a robust, well-connected network with the majority of states participating in food trade. When the magnitude of embodied energy and GHG emissions associated with virtual water are considered, a few key states emerge controlling high throughput in the network.

The objective of this study is to describe a target water–energy–food (WEF) nexus domain world including causal linkages and trade-off relationships between WEF resources and their stakeholders, and to develop a WEF nexus system map as an interdisciplinary tool used for understanding the subsequent complexity of WEF nexus systems. An ontology engineering method, which is a qualitative method, was applied for the replicability of the WEF nexus domain ontology and the map, because ontology engineering is a method of semantic web development for enhancing the compatibility of qualitative descriptions logically or objectively. The WEF nexus system map has three underlying concepts: (1) systems thinking, (2) holistic thinking, and (3) an integrated approach at an operational level, according to the hypothesis that the chains of changes in linkages between water, energy, and food resources holistically and systemically affect the WEF nexus system, including natural and social systems, both temporally and spatially. This study is significant because it allows us to (1) develop the WEF nexus domain ontology database, including defining the concepts and sub-concepts of trade-offs relating to WEF for the replicability of this study; (2) integrate the qualitative ontology method and quantitative network analysis method to identify key concepts serving as linkage hubs in the WEF nexus domain ontology; and (3) visualize human–nature interactions such as linkages between water, energy, and food resources and their stakeholders in social and natural systems. This paper also discusses future challenges in the application of the map for a science–policy–society interface.

Food and water resources are closely interconnected through economic supply chains. Existing studies have identified critical sectors as either direct water users or food consumers indirectly driving upstream water uses. However, sectors acting as intermediate transmission centres in the virtual water network driven by final food demand are overlooked. Production efficiency improvement of these critical transmission sectors (i.e., using less upstream inputs to produce unitary output) could indirectly reduce water uses of the whole supply chains. Taking China as the case, this study identifies critical transmission sectors for food-water nexus at the provincial level, based on an environmentally-extended multi-regional input-output model and the concept of betweenness. Results show that the agricultural products sectors in Shandong, Heilongjiang, and Hubei are the top three transmission sectors. They transmit 4.6, 4.1, and 3.0 billion m³ of embodied water resources, respectively. Some important transmission sectors, such as the cotton in Xinjiang and chemical industry in Jiangsu, cannot be identified by production-based and consumption-based methods. Results also highlight the necessity of strengthening inter-regional and inter-sectoral cooperation, because partial critical transmission sectors are not located in the demand provinces. Betweenness-based results can provide additional hotspots for developing sector-oriented policies for the synergistic management of food and water resources.

The complex relationship between water, energy, food, and ecological systems, known as the WEFE nexus, has emerged as a major topic in the debate about sustainable economic development and resource management. This subject is of special interest in Mediterranean coastal areas as rapid economic expansion driven by population growth, higher influx of tourists, and intensification of agriculture is leading to structural water scarcity conditions. However, addressing the diverse range of issues associated with the nexus is a difficult task due to the existence of intricate interconnections, interdependencies, and nonlinearities within and across its various components. Accordingly, this case study applies a combination of participatory systems modeling and network analysis tools to yield insights into the complexity of this nexus in Axarquia, a region with features that make it an example of water-stressed jurisdictions in the Mediterranean. Overall, our results provide a strong foundation to understand the dynamics that govern this nexus in regions where the availability of freshwater resources is a significant concern. Furthermore, they lay the groundwork for the development of models and scenarios to simulate the impact of various policies and interventions on the overall system.

The world food price crisis in 2007/08 has aroused worldwide attention to the global food price volatility and food self-sufficiency issues. This paper modelled the entire environment of food production and transaction from a holistic view by a Food-Energy-Water (FEW) nexus in order to reveal the hidden connections related to the food self-sufficiency issue, including the interdependencies of food production with its restraining factors (hybrid energy, hybrid water), other production sectors, and international exchanges. This paper mapped all direct and indirect flows in the FEW nexus and projected a potential Emission Trading Scheme (ETS) to figure out the impacts of policies on FEW nexus flows, nexus robustness, total input of all sectors, and household expenditures in Japan and China. The results show that the pattern of food-related extraction flows was more imbalanced than the pattern of hybrid energy flows, due to the high dependence of Japan on the food supply of China (16.11% of total food-related extractions). An ETS may increase Japan’s total household expenditure on imported goods from China in the fields of sugar refining (1.3096%), processing vegetable oils and fats (0.1164%), processing of meat cattle (0.1010%), as well as slightly decrease the system robustness of the total nexus.

Most South Asian countries have challenges in ensuring water, energy, and food (WEF) security, which are often interacting positively or negatively. To address these challenges, the nexus approach provides a framework to identify the interactions of the WEF sectors as an integrated system. However, most nexus studies only qualitatively discuss the interactions between these sectors. This study conducts a systematic analysis of the WEF security nexus in South Asia by using open data sources at the country scale. We analyze interactions between the WEF sectors statistically, defining positive and negative correlations between the WEF security indicators as synergies and trade-offs, respectively. By creating networks of the synergies and trade-offs, we further identify most positively and negatively influencing indicators in the WEF security nexus. We observe a larger share of trade-offs than synergies within the water and energy sectors and a larger share of synergies than trade-offs among the WEF sectors for South Asia. However, these observations vary across the South Asian countries. Our analysis highlights that strategies on promoting sustainable energy and discouraging fossil fuel use could have overall positive effects on the WEF security nexus in the countries. This study provides evidence for considering the WEF security nexus as an integrated system rather than just a combination of three different sectors or securities.

To find a sustainable way of supplying food, energy, and water (FEW) while simultaneously protecting the ecosystem services, it is imperative to build greater understanding on interconnections, feedback, and dependencies in FEW systems. The FEW nexus has developed as a field of study to provide frameworks for such pursuits. Building upon previous work in this paper, we analyze FEW resources through the development of a virtual water trade network using the US network of food and energy flows and their associated virtual water contents. Our main objective is to provide a quantitative estimation of the virtual water embodied in the internal US food and energy transfers and analyze the associated interdependencies of these connections. Three methodological advancements demonstrate the novelty of this work. First, unlike existing FEW virtual water modeling studies, our work separates corn into both food and energy resources accounting for the significant use of corn for ethanol in the United States. Second, we apply recently published water consumption values for energy commodities confirming the variation between previous water footprint studies and these more accurate accounting procedures. Third, we examine network properties of the trade flows furthering FEW nexus literature and showcasing avenues for future research. Our results indicate that accounting for the transfer of corn from the food commodity network to the energy commodity network leads to a virtual water footprint decline of 11% for the cereal grain virtual water network. Additionally, the food trade network shows highly dense and connected properties compared to the energy trade network. Finally, our results indicate that transfers of water footprints between water scarce and water abundant states differ substantially between food and energy virtual water networks. A quantifiable understanding of the water footprint network embodied in the food and energy trade can help in developing policies for promoting conservation and efficiency in the context of the FEW nexus.

The San Antonio Region is home to a rapidly growing population with developing energy and agricultural sectors competing for water, land, and financial resources. Despite the tight interconnectedness between water, energy, and food challenges, little is known about the levels of communication and coordination among the various officials responsible for making the decisions that affect the management and planning of the three resource systems. It has been postulated that efficient communication is a prerequisite to developing resource allocation strategies that avoid potential unintended negative consequences that could result from inefficient allocation of natural resources and competing demands. Factors that may impact communication are identified and their potential roles are considered in improving existing levels of communication between San Antonio's water officials and those at other energy, food, and water institutions in the San Antonio Region. A questionnaire designed to gather information on stakeholder concerns, frequency of communication, and participation in engagement forums was sent to public water officials in the Region. Using social network analysis and bivariate Ordinary Least Square regression analysis, the authors conclude that while modest levels of communication exist among water institutions, a very low level of communication exists between water institutions and those responsible for food and energy. It was further concluded that the frequency of communication among officials at different water institutions is higher among those that participated in stakeholder engagement activities. However, there is insufficient evidence to suggest that participation in stakeholder engagement activities improves communication frequency between water stakeholders and those in the food and energy sectors. There is also insufficient evidence to conclude that people at water institutions in San Antonio would have a higher frequency of communication with other water, energy, and food stakeholder in correlation with a higher level of concern about future water availability in the Region. © 2018 Elsevier B.V.

In the past decade, research on interconnected resource challenges has primarily focused on quantifying physical resource interconnections, and there is a growing focus on the social, economic, and policy dimensions of these interconnections. While the nature of the complexity of interconnected resource challenges resulted in emphasizing the need for inter- and trans-disciplinary research and in increased collaboration between research groups, little work has examined the convergence of perspectives between the research groups and their respective stakeholders. This paper focuses on the San Antonio Region of Texas: a resource hotspot characterized by rapid urbanization, increased energy production in the Eagle Ford Shale Play, and growing agricultural activity. The paper reports on a survey sent to 370 researchers and regional stakeholders from governmental, non-governmental/non-profit, and business organizations in the Region's water, energy, or food sectors. The study goals were to 1) evaluate levels of convergence in perspectives regarding the water, energy, and food challenges in the Region; 2) quantify existing levels of communication of both researchers and regional stakeholders with identified WEF organizations in the region; and 3)identify barriers to and opportunities for improving communication between the WEF organizations and the researchers involved. The authors found aspects of convergence between surveyed regional stakeholders and researchers. Aspects of convergence exist between both groups regarding the potential of different Texas Development Water Board strategies to address future water challenges. Modest levels of communication were reported between surveyed researchers and regional stakeholders with other identified WEF organizations. Both groups converge on the potential roles of “increased communication” and “sharing information between agencies” as a means to improve cooperation to address interconnected resource challenges. To make this possible, institutional mechanisms and resource allocations for such activities must be revisited. © 2019 Elsevier Ltd