Concerns about the water–energy–food (WEF) nexus have motivated many discussions regarding new approaches for managing water, energy and food resources. Despite the progress in recent years, there remain many challenges in scientific research on the WEF nexus, while implementation as a management tool is just beginning. The scientific challenges are primarily related to data, information and knowledge gaps in our understanding of the WEF inter-linkages. Our ability to untangle the WEF nexus is also limited by the lack of systematic tools that could address all the trade-offs involved in the nexus. Future research needs to strengthen the pool of information. It is also important to develop integrated software platforms and tools for systematic analysis of the WEF nexus. The experience made in integrated water resources management in the hydrological community, especially in the framework of Panta Rhei , is particularly well suited to take a lead in these advances.

Measures implemented to restore ecosystem services are widely believed to conflict with food production in the world's irrigated regions because of their competition for scarce water. However, little integrated analysis has been conducted to test this hypothesis. This work tests that hypothesis by presenting results of a basin-scale hydroeconomic analysis linking biophysical, hydrologic, agronomic, ecological, economic, policy, and institutional dimensions of the partially-restored Mesopotamian Marshes of Western Asia. Results serve to partly reject the hypothesis: Here we find that an economically-optimized ecosystem restoration trajectory can be achieved with a minimal loss in food production or farm income where restored wetlands complement important dimensions of food production. Moreover, we find that where water shortage sharing rules can be made more flexible, ecosystem restoration more nearly complements improved food security. Our results point to previously unexplored synergies among food production, ecosystem restoration, and water laws in arid and semi-arid regions internationally.

The water–food–energy Nexus has emerged as a new perspective in debates concerned with balancing potentially conflicting sectoral imperatives of large scale development investments concerned with energy, water or food security. Current frameworks are partial as they largely represent a water-centric perspective. Our hypothesis is that a dynamic Nexus framework that attempts to equally weight sectoral objectives provides a new paradigm for diagnosis and investigation. Dynamic refers here to explicitly understanding (or a diagnosis of) the dynamic relationships and ripple effects whereas static-comparative refers to a comparison of states before and after change. This paper proposes a balanced Nexus framework and presents results from an application to the Mekong basin. The analysis identified the advantages of a sectorally balanced, dynamic Nexus approach, in particular the ability to reveal either the emergence of cross-sectoral connections, or changes in those connections, as a consequence of single sector interventions.

Recent research has documented shifts in per capita trophic interactions and food webs in response to changes in environmental moisture, from the top-down (consumers to plants), rather than solely bottom-up (plants to consumers). These responses may be predictable from effects of physiological, behavioral, and ecological traits on animal water balance, although predictions could be modified by energy or nutrient requirements, the risk of predation, population-level responses, and bottom-up effects. Relatively little work has explicitly explored food web effects of changes in animal water balance, despite the likelihood of widespread relevance, including during periodic droughts in mesic locations, where taxa may lack adaptations for water conservation. More research is needed, particularly in light of climate change and hydrological alteration.

In their opinion paper, Liu et al. highlight the insufficient development of methods such as integrated modelling tools to assess the water–energy–food (WEF) nexus system complexity. This can be attributed to the lack of research programmes addressing the WEF nexus, especially in the European Union. To enable the development of innovative research methods, we need educational and research programmes that explicitly focus on the WEF security nexus. These programmes should promote interdisciplinary approaches that incorporate hydrology as well as sciences related to energy and food security, and environmental governance.

This article examines impacts of infrastructure development and climate variability on economic outcomes for the Amu Darya Basin in Central Asia. It aims to identify the most economically productive mix of expanded reservoir storage for economic benefit sharing to occur, in which economic welfare of all riparians is improved. Policies examined include four combinations of storage infrastructure for each of two climate futures. An empirical optimization model is developed and applied to identify opportunities for improving the welfare of Tajikistan, Uzbekistan, Afghanistan, and Turkmenistan. The analysis 1) characterizes politically constrained and economically optimized water-use patterns for these combinations of expanded reservoir storage capacity, 2) describes Pareto-Improving packages of expanded storage capacity that could raise economic welfare for all four riparians, and accounts for impacts for each of two climate scenarios. Results indicate that a combination of targeted water storage infrastructure and efficient water allocation could produce outcomes for which the discounted net present value of benefits are favorable for each riparian. Results identify a framework to provide economic motivation for all riparians to cooperate through development of water storage infrastructure. Our findings illustrate the principle that development of water infrastructure can expand the negotiation space by which all communities can gain economic benefits in the face of limited water supply. Still, despite our optimistic findings, patient and deliberate negotiation will be required to transform potential improvements into actual gains.

To date, the land–water–food nexus has been primarily addressed from an ecological, hydrological or agronomic angle, with limited response to the governance interface between the input resources. Likewise, in widely used heuristic frameworks, such as the social–ecological system (SES) framework, governance interactions between resources are not sufficiently addressed. We address this gap empirically, using the case of Tajikistan, based on a farm household survey analysis of 306 farmers. The results indicate that land system variables contribute to the willingness to cooperate in irrigation management. Specifically, formal land tenure has a positive effect on farmers paying for water as well as on the likelihood of their investing time and effort in irrigation infrastructure, which is decisive for Tajikistan’s food and fiber production. Irrigation system variables show that, e.g., being an upstream user increases the likelihood to contribute to labor maintenance efforts. We further discuss how decisions with respect to the land sector could be designed in the future to facilitate cooperation in other resource sectors. Further, we conclude from a conceptual perspective that the SES framework integrating a nexus perspective can be adapted: either (1) by adding a second-tier “governance nexus” variable inside the governance variable of an irrigation system; or (2) by adding a land resource unit and system outside the irrigation system.

Efficient use of water and nutrients in crop production are critical for sustainable water and crop production systems. Understanding the role of humans in ensuring water and nutrient use efficiency is therefore an important ingredient of sustainable development. Crop production functions are often defined either as functions of water and nutrient deficiency or are based on economic production theory that conceptualizes production as a result of economic activities that take in inputs such as water, capital and labor and produce crop biomass as output. This paper fills a gap by consistently treating water and nutrient use and human agency in crop production, thus providing a better understanding of the role humans play in crop production. Uptake of water and nutrients are two dominant biophysical processes of crop growth while human agency, including irrigation machine power, land-preparing machine power and human labor force, determine limits of water and nutrient resources that are accessible to crops. Two crops, i.e., winter wheat and rice, which account for the majority of food crop production are considered in a rapidly developing region of the world, Jiangsu Province, China, that is witnessing the phenomenon of rural to urban migration. Its production is modeled in two steps. First water and nutrient efficiencies, defined as the ratios of observed uptake to quantities applied, are modeled as functions of labor and machine power (representing human agency). In the second step, crop yields are modeled as functions of water and nutrient efficiencies multiplied by amounts of water and fertilizers applied. As a result, crop production is predicted by first simulating water and nutrient uptake efficiencies and then determining yield as a function of water and nutrients that are actually taken up by crops. Results show that modeled relationship between water use efficiency and human agency explains 68% of observed variance for wheat and 49% for rice. The modeled relationship between nutrient use efficiency and human agency explains 49% of the variance for wheat and 56% for rice. The modeled relationships between yields and actual uptakes in the second step explain even higher percentages of observed the variance: 73% for wheat and 84% for rice. Leave-one-out cross validation of yield predictions shows that relative errors are on average within 5% of the observed yields, reinforcing the robustness of the estimated relationship and of conceptualizing crop production as a composite function of bio-physical mechanism and human agency. Interpretations based on the model reveal that after 2005, mechanization gradually led to less labor being used relative to machinery to achieve same levels of water use efficiency. Labor and irrigation equipment, on the other hand, were found to be complimentary inputs to water use efficiency. While the results suggest interventions targeting machinery are most instrumental in increasing wheat productivity, they may exasperate rural – urban migration. Policy strategies for alleviating rural-urban migration while ensuring regional food security can nonetheless be devised where appropriate data are available.

Many regions in Africa and the Middle East are vulnerable to drought and to water and food insecurity, motivating agency efforts such as the U.S. Agency for International Development’s (USAID) Famine Early Warning Systems Network (FEWS NET) to provide early warning of drought events in the region. Each year these warnings guide life-saving assistance that reaches millions of people. A new NASA multimodel, remote sensing–based hydrological forecasting and analysis system, NHyFAS, has been developed to support such efforts by improving the FEWS NET’s current early warning capabilities. NHyFAS derives its skill from two sources: (i) accurate initial conditions, as produced by an offline land modeling system through the application and/or assimilation of various satellite data (precipitation, soil moisture, and terrestrial water storage), and (ii) meteorological forcing data during the forecast period as produced by a state-of-the-art ocean–land–atmosphere forecast system. The land modeling framework used is the Land Information System (LIS), which employs a suite of land surface models, allowing multimodel ensembles and multiple data assimilation strategies to better estimate land surface conditions. An evaluation of NHyFAS shows that its 1–5-month hindcasts successfully capture known historic drought events, and it has improved skill over benchmark-type hindcasts. The system also benefits from strong collaboration with end-user partners in Africa and the Middle East, who provide insights on strategies to formulate and communicate early warning indicators to water and food security communities. The additional lead time provided by this system will increase the speed, accuracy, and efficacy of humanitarian disaster relief, helping to save lives and livelihoods.