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.

Water, energy and food are three essential resources for the socio-economic system, and they are interlinked. The coordination of their internal relations is worth studying. We conduct a coordination evaluation method to assess the water-energy-food nexus (WEF Nexus) in China’s provinces. By combining the coupling model and the coupling coordination model, we measure the comprehensive evaluation index and coupling coordination degree of China’s 30 provinces from 2005 to 2017. First, the results show the provincial comprehensive evaluation index had a slow upward trend. The comprehensive evaluation index of the southern region was higher than that of the north, and the eastern was higher than the west. Second, the coordination degree of WEF Nexus in China’s 30 provinces has reached high level in the horizontal coupling stage, and the overall degree of coupling coordination was on the rise. In 2017, the WEF Nexus coupling coordination degree of most provinces reached 0.700 or more, which was intermediate-coordinated. In the six years, the 30 provinces have experienced five types of coupling coordination degree: near coordinated, barely coordinated, primary coordinated, intermediate-coordinated, and well-coordinated.

Water rights transfer is significantly required for alleviating the ever-intensive water crisis, particularly for arid watersheds with abundant farmland and fossil fuels. However, focusing solely on the re-allocation of water rights and disregarding agricultural water saving potential imperil the security of Water-Energy-Food (WEF) nexus. Furthermore, randomness in water availability leads to water shortage risks and subsequent impact on the whole system. In this study, a risk-based optimization model (RWEF) was proposed to promote inter-sectoral water rights transfer through encouraging energy sector to invest in agricultural water-saving works and get paid back in water rights. Chance-constrained programming is incorporated to analyze the trade-offs between system benefits and water-shortage risks. The developed model was applied to the Inner Mongolia section of the Yellow River Basin, China to verify its effectiveness, considering different development levels of food and energy industries. Results indicated that 488 million m³ of water could be transformed from agriculture to energy, without compromising agricultural production. The main recipients of transferred water rights would be traditional coal-based industries, while it would be difficult for thermal power and most modern coal chemical industries to participate. The construction of water-saving works would help safeguard agricultural production under risks. Compared against two alternative models without water rights transfer mechanism, the average benefit acquired from RWEF under varied water-shortage risks would be at least 68% higher. Particularly, when confronted with extreme water-shortage risk and increased production demands, RWEF would still be able to support agricultural and energy production, while the alternative models being incapable.

With the rapid development of society and economy, changes happened dramatically in the food consumption and structure among Chinese residents. This paper analyzes the impact of residents' food consumption on water resources in China from the perspective of water footprint (WF), which is important to promote water conservation from the consumption side. After calculating the WFs of urban and rural residents' food consumption, the paper explored the drivers of WFs through the extended Stochastic Impacts by Regression on Population, Affluence, and Technology (STIRPAT) model, and then scenario analysis was applied to investigate how to reduce water depletion of food consumption in China. The results showed that (1) There were increasing trends in the per capita WFs of urban and rural residents' food consumption from 2000 to 2020, and the per capita WFs in urban were higher than that of rural. (2) Between 2000 and 2020, the total WFs of urban residents' food consumption had risen by 370.20 billion m³, while the total WFs had decreased from 407.20 billion m³ to 310.64 billion m³ in rural as urbanization increased. (3) Consumption quantity and population size were the main factors driving the changes in WFs of food consumption between urban and rural residents. (4) Under the scenarios of baseline, consumption upgrading, and saving food, an upward tendency could be observed in the WFs of rural residents' food consumption, while the WFs were expected to peak around 2030 in urban. This paper argued that it was possible to achieve the goal of reducing water depletion by controlling the food consumption of urban and rural residents. Under these conditions, this paper proposes to develop a water-saving consumption pattern in terms of optimizing the dietary structure and advocating food conservation between urban and rural residents.

Understanding the status of water-energy-food (WEF) Nexus, oriented to the whole process of water extraction and deployment, water consumption for crop growth, and food production output, in irrigation systems is essential for food security and resources sustainability. Based on WEF Nexus quantification, combining traditional agricultural water-saving and water footprint theory, the sustainable development level (SDL) of water acquisition-transfer-consumption process for pumped irrigation systems was analyzed, using the principal component analysis (PCA) and taking the Lianshui Irrigation District (LID) in eastern China as a case study, in this paper. The driving mechanism of SDL for WEF Nexus was revealed by virtue of the partial least-squares regression (PLSR). Results showed that, annual SDL of the WEF Nexus in the pumped irrigation systems was 0.3 during the study period 2005–2019, mainly due to the low SDLₑ and SDLf, indicating that sustainability had been concerned. PRE and RRI were significant-positive factors, while CDI functioned as significant-negative driving factors on SDL of WEF Nexus. The measures adjusting crop planting structure, transforming irrigation and drainage mode, updating water pump equipment, and increasing agricultural investment contribute to the sustainability of WEF Nexus in the observed irrigation systems. Therefore, the sustainable management can be implemented according to the unique driving factors identification of WEF Nexus in pumped irrigation systems. The research is conducive to the management and program for irrigated agricultural systems under the changing circumstances.

Water, energy, and food are essential and strategic resources for human well-being and socio-economic development and form the water-energy-food (WEF) system with competition and synergy. The competitive and synergistic evolution model was developed to remedy the limitations in quantitatively analyzing the tradeoffs and synergies of the WEF system. Firstly, an assessment model was developed for measuring the synergy and competition of the WEF system based on the order degree of each subsystem (That is, the development degree of each subsystem) and synergy theory. Then the synergy evolution model (SEM), with the help of a logistic model and accelerated genetic algorithm (AGA) model, was developed to measure and identify the steady-state. Furthermore, an empirical study was conducted with 30 provinces in China as examples. The results indicated that the food subsystem had the highest average order degree (0.347), followed by the energy subsystem (0.305), and the water subsystem had the lowest (0.281). The degree of order of the three subsystems exhibited an upward trend in time and has differences in the spatial distribution. Also, the results showed that synergistic, restrictive, and competitive relationships exist within the WEF system. Areas with competitive and restrictive relationships are mainly located in South China and North China, respectively, within the relationship between the water and energy subsystems. The entire country showed a restrictive relationship between the water and food subsystems. The energy and food subsystems showed that the eastern regions with relationship, while the western regions with competitive and restrictive relationship. Finally, effective measures (e.g., optimize the industrial structure, continuing to implement the strategy of “storing grain in the land and technology”, and to hold the arable land minimum) are suggested to achieve the WEF system coordinated and sustainable development. We believe that the assessment model is also applicable to assess the other complex and dynamic system worldwide that involve multiple factors.

The food–water–land–ecosystem (FWLE) nexus is fundamental for achieving sustainable development. This study examines the influence of urbanization on the FWLE nexus. Toward this end, land was deemed as an entry point. Therefore, the impact of urbanization on the nexus was explored based on changes in land use. We selected Shenzhen, a city in China, as the study area. First, a land change modeler was employed to analyze historical land-use changes from 2000 to 2010, to build transition potential submodels, and to project future land-use patterns for 2030 under a business-as-usual scenario. Second, based on land-use maps, we assessed habitat quality, water yield, and water supply from 2000 to 2030 using Integrated Valuation of Ecosystem Services and Tradeoffs. Moreover, crop production was estimated according to statistical materials. Finally, the study presents the analyses and discussion of the impacts of urbanization on ecosystem services related to the FWLE nexus. The results of land-use changes indicated that a significant expansion of artificial surfaces occurred in Shenzhen with varying degrees of decrease in cultivated land, forest, and grassland. Furthermore, habitat quality, water supply, and crop production decreased evidently due to rapid urbanization. In contrast, the total water yield indicated an upward trend owing to the increased water yield from increasing artificial surfaces, whereas water yield from other land-use areas declined, such as the forest and grassland. The results demonstrated a significant positive correlation between artificial surfaces and total water yield. However, negative correlations were observed in the interaction among habitat quality, water supply, and crop production. The study presented temporal and spatial assessments to provide an effective and convenient means of exploring the interactions and tradeoffs within the FWLE nexus, which, thus, contributed to the sustainable transformation of urbanization.

The increasing pressures of global warming, population growth and epidemic occurrence are causing challenges in meeting the growing requirements for water, energy and food. In particular, the contradiction between the supply and demand for water, food, and energy is exacerbated by inefficient resource utilization and carbon emission increase. Incorporation of the interlinked aspects of water, energy, food and carbon emissions from agricultural systems into one water-food-energy-carbon nexus facilitates integrated resource management. Biochar application to farmland is a potential strategy for carbon management and agricultural productivity improvement. The integration of biochar systems and the water-food-energy-carbon nexus is an efficient and coordinated alternative method for sustainable agricultural management and a crucial strategy for addressing water, energy and food security issues. Accordingly, this paper proposes an approach for the synergistic regulation of water, land, energy, and carbon emissions in a circular agricultural system by balancing water supply and demand, land allocation, electricity consumption, and economic upgrading principles. A two-stage circular agriculture framework is constructed, with biochar and electricity generated from agricultural residues at the first stage and employed at the second stage. Economic-environmental-energy harmonization is considered in the methodology, and the agrotechnical potential of biochar is quantified via crop yield increase and greenhouse gas emission reduction functions. This approach can assist decision makers in providing the best policy options given certain agricultural resources to achieve the maximum economic performance of the system while minimizing environmental side effects. In this paper, the model framework is applied to the Sanjiang Plain in northeastern China to verify the feasibility of the approach. The results indicate that the external electricity demand is reduced by 87.8% due to the generation of biofuels. Cropland greenhouse gas emissions are reduced by 34.09%–67.06% via the application of biochar. This study proposes an optimization method with important implications for the improvement of regional cropland management techniques and development of sustainable circular agriculture. This methodology can be extended to other agriculture-centered regions with limited resources and environmental problems.

Under the double pressure of ecological vulnerability and economic development, natural resources and ecological environment have become the key constraints to the development of the Yellow River Basin (YRB). This paper proposed a theoretical framework for the relationship between water-energy-food (WEF) and poverty. An improved coupling coordination degree model and the geographical detector were used to evaluate the spatio-temporal coupling between WEF and poverty and its influencing factors in YRB. The results suggest that the levels of coupling coordination increase to different degrees in YRB and its provinces from 2000 to 2019, and the coupling types are characterized by pyramidal-shaped distribution. The regions of YRB are divided into four development types: water-driven type, energy-driven type, food-driven type, and economy-driven type. Spatially, a dominant factor zone is formed with a multi-polar core. Furthermore, some practical suggestions are put forward to promote the effective utilization of water resources and high-quality development according to specific regional situations in YRB. This study will promote coupling coordination and high-quality development in YRB, providing a reference for the coordination of the human-land relationship and regional sustainable development.