Quantifying the interactions of the food-energy-water (FEW) nexus is crucial to support new policies for the conjunctive management of the three resources. Currently, our understanding of FEW systems in metropolitan regions is limited. Here, we quantify and model FEW interactions in the metropolitan area of Phoenix, Arizona, using the Water Evaluation and Planning (WEAP) platform. In this region, the FEW nexus has changed over the last thirty years due to a dramatic population growth and a sharp decline of cultivated land. We first thoroughly test the ability of WEAP to simulate water allocation to the municipal, agricultural, industrial, power plant, and Indian sectors against historical (1985–2009) data. We then apply WEAP under possible future (2010–2069) scenarios of water and energy demand and supply, as well as food production. We find that, if the current decreasing trend of agricultural water demand continues in the future, groundwater use will diminish by ~23% and this would likely result in aquifer safe-yield and reduce the energy demand for water. If agricultural activities decrease at a lower rate or a multidecadal drought occurs, additional (from 7% to 33%) water from energy-intensive sources will be needed. This will compromise the ability to reach safe-yield and increase energy demand for water up to 15%. In contrast, increasing the fraction of energy produced by solar power plants will likely guarantee safe-yield and reduce energy demand of 2%. This last solution, based on an expanded renewable portfolio and current trends of municipal and agricultural water demand, is also projected to have the most sustainable impacts on the three resources. Our analytical approach to model FEW interconnectivities quantitatively supports stakeholder engagement and could be transferable to other metropolitan regions.

Water and food are facing increased demands from larger and more affluent populations thus necessitating a coordinated and effective management of limited natural resources. In this study, we present an optimization model developed for optimal resource allocation towards sustainable water and food security under nutritional, socio-economic, agricultural, environmental, and natural resource constraints. The core objective of this model is to maximize the composite water-food security status by defining an optimal water and agricultural policy that ensures nutritional guidelines while still maintaining food-preferences. This policy transforms optimum food demands into optimum cropping options given the water and land footprints of each crop or agricultural product. The model performance is evaluated with a hypothetical regional case study testing a wide spectrum of cases from the water-stressed to the land-stressed extremes thus showing the model's ability to suggest fundamentally different policy approaches. Results demonstrated the sensitivity of adopted water and food security definitions in shaping water and agricultural policies, thus reinforcing the need for agreements amongst the wide range of stakeholders at global scale.

Given their substantial societal benefits, such as supporting economic activities and providing better livelihoods in rural areas, ecosystem services should gain higher importance in water-food-energy nexus debates. Yet, not all values from ecosystems are quantifiable, data is often not adequate and methods of measuring these values are not sound. This situation challenges researchers and water managers to improve research tools and give adequate attention to ecosystem services by implementing interdisciplinary approaches and integrated management of ecosystems and their services.

Food and water security have moved to the top of the global agenda following the food and energy price increases that started in 2007. Addressing the food, water and energy nexus is considered increasingly important for transparently and equitably meeting increasing global demand without compromising sustainability. This paper argues that given the unique regional and sector challenges of food, water and energy security, their nexus must be deconstructed to find effective, contextualized solutions. And governance challenges are at the heart of the nexus in each region. Governance is defined in various ways, but, with a few notable exceptions, the definitions have undergone relatively little analysis. In turn, governance issues are imbedded in policy, institutional, technological and financing options exercised at the global, regional, national and local levels. Furthermore, strong interactions between levels prompt policy responses to specific events and outcomes. The cu rent governance arrangements, where they exist at all, are woefully inadequate to address the challenges. They are imbedded in a lack of strategic clarity, and among stakeholders there is an unequal distribution of power, voice and access to information, resources and the capability to exercise a sound influence which will produce equitable and sustainable outcomes. Often there are huge tradeoffs between the short-term wins of individual stakeholders and long-term holistic solutions. This paper uses illustrative examples from recent global developments, as well as from China and India, to make the case for placing empirical analysis of governance issues at the top of the global agenda. At each level, governance is ues affect the choice of policies, institutions and outcomes for addressing these daunting challenges.

Given their substantial societal benefits, such as supporting economic activities and providing better livelihoods in rural areas, ecosystem services should gain higher importance in water-food-energy nexus debates. Yet, not all values from ecosystems are quantifiable, data is often not adequate and methods of measuring these values are not sound. This situation challenges researchers and water managers to improve research tools and give adequate attention to ecosystem services by implementing interdisciplinary approaches and integrated management of ecosystems and their services.

Studies on the Food-Energy-Water Nexus can help researchers, policy makers, practitioners, and stakeholders identify opportunities to maintain the nexus’ synergies and trade-offs. Water, the most sensitive element in the Food-Energy-Water Nexus, readily influences the stability, cooperativity, and safety of the nexus. The key initiative to ensure water security in the Food-Energy-Water Nexus is properly handling water for food and energy production, but the existed conceptual framework and evaluation system are incomplete. This paper uses the Driver-Pressure-State-Impact-Response model and the water footprint theory to construct an optimization approach to evaluate the synergy and competition for water between food and energy at five levels. This optimization approach was tested and implemented based on a case study of 31 provinces in the Chinese Mainland from 1997 to 2016. The results showed that the blue water footprint of 31 provinces was 263.48 Gm³ in 2016, and the gray water footprint was 1518.57 Gm³, which led to inter-industry competitive water use and water unsustainability. In 2016, the 31 provinces had developed into Industry Synergy Sustainability scenario (1 province), Industry Synergy Unsustainability scenario (9 provinces), Industry Competition Unsustainability scenario (16 provinces), and Industry Competition Sustainability scenario (5 provinces), presenting a spatially clustered distribution pattern. Except for Xinjiang and Jilin, the remaining 29 provinces gradually developed into sustainable or synergistic scenarios. The total production water footprint in the Industry Competition Unsustainability scenario reached 4.08 m³/kg in 2016, while the Industry Synergy Sustainability scenario was only 3.67 m³/kg. This paper proposes two response paths, based on market allocation and administrative means, to facilitate the gradual evolution of the Industry Competition Unsustainability scenario into the Industry Synergy Sustainability scenario. These paths contribute to the efficient and sustainable integrated management of food, energy, and water globally.

Studies on the food, energy, and water (FEW) nexus lay a shared foundation for researchers, policy makers, practitioners, and stakeholders to understand and manage linked production, utilization, and security of FEW systems. The FEW nexus paradigm provides the water community specific channels to move forward in interdisciplinary research where integrated water resources management (IWRM) has fallen short. Here, we help water researchers identify, articulate, utilize, and extend our disciplinary strengths within the broader FEW communities, while informing scientists in the food and energy domains about our unique skillset. This paper explores the relevance of existing and ongoing scholarship within the water community, as well as current research needs, for understanding FEW processes and systems and implementing FEW solutions through innovations in technologies, infrastructures, and policies. Following the historical efforts in IWRM, hydrologists, water resources engineers, economists, and policy analysts are provided opportunities for interdisciplinary studies among themselves and in collaboration with energy and food communities, united by a common path to achieve sustainability development goals.

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.

Water plays a crucial role in our food systems and food security. However, the essential role of water for a functioning food system and the impacts of food systems on water availability and quality have not yet been adequately recognized. Due to a lack of coordination among water and food systems actors, there are siloed water, food security, and nutrition strategies. This paper presents the case to make water pivotal in designing food systems, laying out action perspectives for different actors to move toward what we call “water-responsible food systems”. This paper is based on input from many participants during workshops and existing literature. A food systems approach provides an excellent entry point to link food with water considering climate change and energy. Moreover, collective and cross-cutting actions between actors in food systems are essential to make decisive progress, as well as a common language and insight into the trade-offs of the multiple values of water for a clear prioritization of water use and allocation.

The complexity of water, food and energy security is analysed from the perspectives of (i) water and food and (ii) water and energy and their interconnectivity and focuses ultimately on water as a primary input into processes, the entry point for participants of the Third World Irrigation Forum. The paper provides an overview of trends in water, food and energy security, highlights the interconnectivity between the various elements and introduces the water–food–energy nexus as a tool for improving productivity and sector policies, avoiding unintended consequences on other sectors. Invariably, there will be trade‐offs and the challenge is to find combinations of measures that have a net positive outcome. In order to quantify security in the three elements and the trade‐offs between them, emerging modelling approaches for the nexus are discussed. Sub‐theme 3 of the forum focuses on productivity and technology interventions¹ and sub‐theme 2 on stakeholder interaction. The combination of modelling, technology innovations and stakeholder participation in a water–food–energy nexus approach leads to better understanding of linkages and more robust policies and is used to derive recommendations for an enabling policy environment.