In the real decision-making process, there are so many time series values that need to be aggregated. In this paper, a visibility graph power geometric (VGPG) aggregation operator is developed, which is based on the complex network and power geometric operator. Time series data are converted into a visibility graph. A visibility matrix is developed to denote the links among different time series values. A new support function based on the distance of two values are proposed to measure the support degree of each other when the two time series values have visibility. The VGPG operator considers not only the relationship but also the similarity degree between two values. Meanwhile, some properties of the VGPG operator are also investigated. Finally, a case study for water, energy, and food coupling efficiency evaluation in China is illustrated to show the effectiveness of the proposed operator. Comparative analysis with the existing research is also offered to show the advantages of the proposed method.

Climate change, population growth, and economic development pose critical challenges in providing water, energy, and food security at the national and global scale. The Middle East is of particular interest due to the rapid industrialization, fragile environment, non-stable political relations, and transboundary water conflicts. Transboundary water plays a crucial role in sustainable development of the Middle East countries. Among them, Iran, Iraq, and Turkey shared major transboundary river basins which induced huge potential risks and benefits associated with development. The research on Water-Energy-Food (WEF) nexus has seen a significant increase to productively assess water, energy, and food dependence at a higher resolution. According to these researches, drivers impacting the WEF security in the Middle East are water scarcity, migration, extreme events, economic growth, urbanization, population growth, poverty and political stability. Therefore, it is important to investigate the dynamics behind the WEF security concerns in this region. The results show that most countries in the Middle East are facing WEF resources insecurity owing to weak planning or wrong management strategies. Based on WEF Security Index reports, WEF Index for Iran, Iraq, and Turkey is 0.68, 0.65, and 0.75, respectively. According to the Food and Agriculture Organization of the United Nations (FAO) reports, water, energy, and food demands increased with population growth from 1997 to 2017, which could enhance potential of conflict over water especially on transboundary water resources. This review explores the WEF nexus as a holistic approach to seek regional solutions to common challenges in these countries. In this case, cooperation and collaboration between scientific communities, stakeholders, and decision-makers is vital to address the complexity of the resource management and development challenges regarding the WEF security.

An interval-stochastic-fuzzy policy analysis model is proposed to generate optimal security management policy for a water–energy–food nexus system of the urban agglomeration under multiple uncertainties. A number of planning policies under interval-stochastic surface water and groundwater conditions are obtained. Ranking scores of all policies in descending order, policy with the highest score is the best choice. Results disclose that (a) interval-stochastic available water resources lead to changing system benefits. (b) The shares of cropland area targets are 2.7% (Xiamen), 42.6% (Zhangzhou), and 54.7% (Quanzhou). (c) Different available water scenarios result in varied irrigation patterns. (d) Surface water takes a high fraction of the total water supply (about [71.34, 73.68]%), diesel agricultural machinery service more than 60% of the total cropland. (e) Zhangzhou contributes about 50.01% of total TN and TP emissions, while Quanzhou contributes about 50.61% of total carbon emission. (f) Security level of policies would change with the varied σ and α values, due to the risk attitudes of policy makers. (h) Sweet potato and others are the crops with the highest safety performance; (i) Zhangzhou is the city with highest comprehensive safety performance.

Water is a fundamental component in primary food production, whether it be rainfall, irrigation used to water crops, or for supplying drinking water for animals, while the amount of water in the soil determines it capacity to support machinery and animals. We identify that UK agriculture is exposed to five main water-related risks: agricultural drought, scarcity of water resources, restrictions on the right to abstract water, excess soil water, and inundation. Projected milder, wetter winters and hotter, drier summers by the end of the century will change the frequency, persistence, or severity of each of these risks. This paper critically reviews and synthesizes the scientific literature on the impact of these risks on primary food production and the technological and managerial strategies employed to build resilience to these changing risks. At the farm scale, the emphasis has been on strategies to build robustness to reduce the impact of a water-related risk. However, collaborative partnerships allow for a more optimal allocation of water during times of scarcity. Enhancing cross-scale interactions, learning opportunities, and catchment-scale autonomy will be key to ensuring the agricultural system can build adaptive and transformational capacity.

Food, energy, and water (FEW) nexus studies require reliable estimates of water availability, use, and demand. In this regard, spatially distributed hydrologic models are widely used to estimate not only streamflow (SF) but also different components of the water balance such as evapotranspiration (ET), soil moisture (SM), and groundwater. For such studies, the traditional calibration approach of using SF observations is inadequate. To address this, we use state-of-the-art global remote sensing-based estimates of ET and SM with a multivariate calibration methodology to improve the applicability of a widely used spatially distributed hydrologic model (Noah-MP) for FEW nexus studies. Specifically, we conduct univariate and multivariate calibration experiments in the Mississippi river basin with ET, SM, and SF to understand the trade-offs in accurately simulating ET, SM, and SF simultaneously. Results from univariate calibration with just SF reveal that increased accuracy in SF at the cost of degrading the spatio-temporal accuracy of ET and SM, which is essential for FEW nexus studies. We show that multivariate calibration helps preserve the accuracy of all the components involved in calibration. The study emphasizes the importance of multiple sources of information, especially from satellite remote sensing, for improving FEW nexus studies.

Agricultural and electric productions are the main water consumers. They are intricately interlinked and complicated. An uncertain water-food-energy (WFE) nexus model could well reflect the complex relationships among water, agriculture, and electricity. Chance-constrained fuzzy fractional programming (CFFP) method is proposed to reflect the uncertainties in WFE nexus system. It can handle multi-objectives expressed as output/input ratio problems in a fuzzy and random environment. Then, the CFFP-based WFE model is applied to Kaikong watershed (a water-scarce region in northwest China). Water resources utilization, agricultural land allocation and electricity generation are incorporated into the nexus framework for pursuing the maximum water use efficiency (i.e., unit water benefit). Uncertainties in water availability, water demand, and pollutant/CO₂ emission have synergistic effects on agricultural and electric productions. The unit water benefit ranges from 0.852 to 0.926 $/m³ across 144 scenarios. Results suggest that, at the end of planning horizon, irrigated agricultural area should be controlled below 203.4 × 10³ ha, and vegetable is encouraged. Proportion of fossil-energy power (i.e. coal- and gas-fired electricity) is optimized within 53.1 %–60.4 % in adaption to water and environment constraints. The obtained results can efficiently help optimize use of limited resources, and provide a synergic management strategy for regional sustainability.

The water-energy-food nexus concept is criticized as not yet fit for deeply integrated and contested governance agendas. One problem is how to achieve equitable risk governance and management where there is low consensus on priorities, poor inclusion and coordination of risk assessment procedures, and a weak emphasis placed on cross-scale and sectoral interactions over time. Participatory system dynamics modeling processes and analyses are promising approaches for such challenges but are currently underutilized in nexus research and policy. This paper shares our experience implementing one such analysis in the Mekong river basin, a paradigmatic example for international nexus research. Our transdisciplinary research design combined participatory causal loop diagramming processes, scenario modeling, and a new resilience analysis method to identify and test anticipated water-energy-food risks in Kratie and Stung Treng provinces in northeastern Cambodia. Our process generated new understanding of potential cross-sectoral and cross-level risks from major hydropower development in the region. The results showed expected trade-offs between national level infrastructure programs and local level food security, but also some new insights into the effects local population increases may have on local food production and consumption even before hydropower developments are built. The analysis shows the benefit of evaluating risks in the nexus at different system levels and over time because of how system dynamics and inflection points are taken into account. Additionally, our case illustrates the contribution participatory system-thinking processes can make to risk assessment procedures for complex systems transitions. We originally anticipated that any new capacity reported by partners and participants would come from our modeling results produced at the end of the process. However, participants in the modeling procedures also found the experience powerful the information sharing, rapid risk assessment, and personal learning it enabled. A lesson from our experience reinforces a message from the transdisciplinary research field that has not yet been absorbed into the nexus research and policy field wholeheartedly: we do not have to wait for perfect data and incontestable results before making a positive contribution to anticipating and responding to risks that emerge from nexus relations if we apply participatory and systems-thinking informed approaches. | publishedVersion

Aquatic ecosystems are used for extensive rice-shrimp culture where the available water alternates seasonally between fresh and saline. Poor water quality has been implicated as a risk factor for shrimp survival; however, links between shrimp, water quality and their main food source, the natural aquatic biota inhabiting these ponds, are less well understood. We examined the aquatic biota and water quality of three ponds over an entire year in the Mekong Delta, Vietnam, where the growing season for the marine shrimp Penaeus monodon has been extended into the wet season, when waters freshen. The survival (30–41%) and total areal biomass (350–531 kg ha⁻¹) of shrimp was constrained by poor water quality, with water temperatures, salinity and dissolved oxygen concentrations falling outside known optimal ranges for several weeks. Declines in dissolved oxygen concentration were matched by declines in both shrimp growth rates and lipid content, the latter being indicative of nutritional condition. Furthermore, as the dry season transitioned into the wet, shifts in the taxonomic composition of phytoplankton and zooplankton were accompanied by declines in the biomass of benthic algae, an important basal food source in these systems. Densities of the benthic invertebrates directly consumed by shrimp also varied substantially throughout the year. Overall, our findings suggest that the survival, condition and growth of shrimp in extensive rice-shrimp ecosystems will be constrained when poor water quality and alternating high and low salinity negatively affect the physiology, growth and composition of the natural aquatic biota. Changes in management practices, such as restricting shrimp inhabiting ponds to the dry season, may help to address these issues and improve the sustainable productivity and overall condition of these important aquatic ecosystems.

There is an increasing appreciation that food–energy–water (FEW) nexus problems are approaching criticality in both the developing and developed world. As researchers and managers attempt to address these complex resource management issues, the concept of the FEW nexus has generated a rapidly growing footprint in global sustainability discourse. However, this momentum in the FEW nexus space could be better guided if researchers could more clearly identify what is and is not a FEW problem. Without this conceptual clarity, it can be difficult to defend the position that FEW innovations will produce desired outcomes and avoid unintended consequences. Here we examine the growing FEW nexus scholarship to critically evaluate what features are necessary to define a FEW nexus. This analysis suggests that the FEW nexus differs from sector-focused natural resource or sustainability problems in both complexity and stakes. It also motivates two new foci for research: the identification of low-dimension indexes of FEW system status and approaches for identifying boundaries of specific FEW nexuses.

Continued rise in global human population, per capita consumption, urbanization and migration towards coastal cities present challenges in fulfilling the energy, water and food demands of coastal communities in sustainable manner. In this regard, as a solution to the problem, a new multigeneration system is proposed to address some of the most common and vital needs of such communities. The system developed is based on principles of sustainability and decentralisation and is driven by renewable energy sources including sun and biomass. It provides electricity, fresh water, hot water for domestic use, HVAC for space air-conditioning and food storage, in addition to hot air for food drying. In the proposed hybrid system, biomass energy is integrated with solar energy in a complimentary manner as a means to maximise outputs and enhance system resilience against weather conditions and day/night cycles. Designing for resilience enables a type of operation that fulfils parallel demands in a continuous stable and flexible operation which can be optimised depending on the requirements. The main sub-systems used in the proposed multigeneration system consist of a Biomass combustor, Concentrated Solar Power (CSP), a Rankine Cycle, a desalination unit and an Absorption Cooling System (ACS). A comprehensive integrated thermodynamic model of the entire system is developed by application of energy, mass, entropy and exergy balance equations. Moreover, effects of various inputs and environmental variables on the outputs and performance has also been studied. Results reveal that the proposed system is capable of fulfilling some of the coastal community’s essential requirements in an efficient and ecologically benign manner. The energy and exergy efficiencies of the proposed system are 55% and 18%, respectively. The outputs of the system include 1687 m³/day of produced fresh water, ~4 MW of cooling, ~13 MW of electricity, ~73 kg/s of hot air for food drying, and ~41 kg/s of hot water for domestic use. Furthermore, the highest amount of exergy destruction is observed in biomass combustion unit and the solar PTCs.