"Water, energy and food are key resources to sustain life, and are fundamental to national, regional, and global economies. These three resources are interlinked in multiple ways, and the term 'nexus' captures the interconnections. The nexus has been discussed, debated, researched, and advocated widely but the focus is often on the pairings of 'water-energy' or 'water-food' or 'energy-food'. To really benefit from the nexus approach in terms of resource use efficiency, it is essential to understand, operationalize, and practice the nexus of all three resources. As demand for these resources increases worldwide, using them sustainably is a critical concern for scientists, citizens, governments, and policymakers. Water-Energy-Food Nexus: Principles and Practices is a valuable resource for students, research scholars, and professionals in academic institutions with strong interests in interdisciplinary research involving geography, earth science, environmental science, environmental management, sustainability science, international development, and ecological economics. The volume will also be useful for professionals, practitioners and consultants in NGOs, government, and international agencies"--Back cover.

Global challenges have exacerbated a search for solutions to poverty and environmental degradation. Integration it was argued would help address the twin challenge. Integrated Water Resources Management (IWRM) was supposed to be that magic bullet and was embraced by scientists because of the clinical efficiency with which it argued for integrated analysis of sectors and resources and of systems and scale conditions. This paper argues that effective implementation of the Water-Energy-Food (WEF) Nexus can be supported by robust science. The corollary that robust science automatically leads to effective implementation is not always known to be true. The nexus approach sheds light on the challenges of implementation by introducing concepts of trade-offs and thresholds and consequently emphasizes the importance of transdisciplinary approaches to sustainable development. This paper reviews the results of recent research to offer tentative answers to the following questions: (a) Why is the governance dimension important to undertake an integrated analysis of water-energy-food challenges? (b) What does the nexus approach connote in normative and institutional terms? (c) What does implementation mean in nexus terms? (d) How can we establish if the nexus approach is an improvement over business as usual? and (e) What tools are available that would enable translation of results of scientific research to create an evidence base that would enable decision makers to act in support of sustainable development?

The review papers presented in this special issue all derive from an NSF sponsored workshop held in January 2017, in College Station, Texas: FEW Nexus Workshop on Integrated Science, Engineering, and Policy: a Multi Stakeholder Dialogue Symposium. The workshop was organized by the Texas AM WEF Nexus Initiative, and their scientific committee partners: Prairie View AM and Texas AM-San Antonio, Purdue University, Ohio State University, National Council for Science and Environment (NCSE), Columbia University, World Wildlife Federation, University of Texas, Rice University, Los Alamos National Lab, Future Earth, Texas Christian University, Circle of Blue, University of California-Riverside, International Food Policy Research Institute, National Renewable Energy Laboratory, University of New Mexico, Pennsylvania State University, University of Minnesota, and Water Future. The papers represent the work of the scientists and professionals hailing from the private and industrial sectors, government agencies, and research and educational institutions.

Population growth, increasing demands for food, ever-growing competition for water, reduced supply reliability, climate change and climate uncertainty and droughts, decline in critical ecosystems services, competition for land use, changing regulatory environments, and less participatory water resources governance are contributing to increasing difficulties and challenges in water resource management for agriculture and food. The need for sustainable food security for our global population and the need for preserving the environment, namely natural and man-made ecosystems and landscapes, have created an increased need for integrated, participative and scalable solutions focusing the various levels of irrigation and nature water management, from the field crop to the catchment and basin scales. Meanwhile, challenges and issues relative to water management for agriculture and food have evolved enormously in the last 30 years and the role of active management of the components of the water cycle is assuming an increased importance since their dynamics are key to assure water use sustainability, mainly agriculture and natural ecosystems sustainability. However, different regions face context-specific challenges associated with water scarcity, climate, governance, and population requirements. The main and first challenge is producing enough food for a growing population, which is intimately related with challenges placed to agricultural water management, mainly irrigation management. This paper revises challenges and progress achieved in the last 30 years focusing on irrigated agriculture, mainly water management, and its contribution to food security and the welfare of rural communities.

Water, energy, and food and are strongly interconnected, and the sustainability of the whole world depends on this link. The aim of this article is to analyze the volatility spillovers between indexes representing the financial component of this nexus. We use a multivariate Generalized Autoregressive Conditional Heteroskedasticity (GARCH) model with daily data in which the water variable is proxy by equity index that represents the performance of the industry involved in water business both at the global and local levels. For the food and energy sectors, we use two sub-indexes of the S&P Goldman Sachs (GS)-Commodity Index. Our results highlight the existence of a financial nexus between water, energy, and food that was particularly exacerbated during 2008 crisis. Evidence therefore suggests the need to better investigate the policy options that can be used to reduce price volatility in a framework of the rising relevance of sustainability issues.

Water, food and energy are strongly interconnected. In this study we address this issue taking the lens of financial concerns to investigate the WFE relationship. Specifically, the aim of our paper is to analyze the volatility spillovres between indexes representing the financial component of WFE nexus. We use a multivariate GARCH model with daily data from November 2001 to May 2013. Water is proxy by equity index that represents the performance of the industry involved in water business both at global and local level. For the food and energy sectors we use two sub-indexes of S&P GF-Commodity Index. Our results highlight the existences of a financial nexus between WFE that is particular exacerbated during 2008 crisis. Evidence therefore suggests the need to better investigate the policy options that can be used to reduce price volatility in a framework of a rising relevance of water issues within the nexus.

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.