China's food production depends highly on irrigation, but irrigated agriculture has been threatened by increasing water scarcity. As such, the overall goal of this study is to provide a better understanding of the changing trends in water supply and demand balance, their impacts on food production, and government policy responses. The results show that water scarcity in China is a regional issue, mainly in northern areas. This is reflected in the limited and uneven distribution of water resources, decline of surface water resources, depletion of groundwater resources, degradation of water quality and increasing water demand. Climate change has further aggravated water scarcity in several river basins in northern China, resulting in the reduction of irrigated areas and a fall in food production. Consequently, the Chinese government has tried to control total water withdrawal, improve water use efficiency, and control water pollution. While these policy responses are encouraging, their effectiveness in resolving the growing water scarcity in China needs to be examined.

The water-energy-food (WEF) nexus concept highlights the importance of integrative solutions that secure resource supplies and meet demands sustainably. There is a need for translating the nexus concept into clear frameworks and tools that can be applied to decision making. A simulation and analytics framework, and a concomitant Nexus Simulation System (NexSym) is presented here. NexSym advances the state-of-the-art in nexus tools by explicit dynamic modelling of local techno-ecological interactions relevant to WEF operations. The modular tool integrates models for ecosystems, WEF production and consumption components and allows the user to build, simulate and analyse a “flowsheet” of a local system. This enables elucidation of critical interactions and gaining knowledge and understanding that supports innovative solutions by balancing resource supply and demand and increasing synergies between components, while maintaining ecosystems. NexSym allowed assessment of the synergistic design of a local nexus system in a UK eco-town. The design improved local nutrient balance and meets 100% of electricity demand, while achieving higher carbon capture and biomass provisioning, higher water reuse and food production, however with a remarkable impact on land use.

Optimal allocation of available water in a middle Himalayan watershed by a linear programming model for maximizing production from crops and livestock, after meeting the present and future demands of human and environmental flows, was analyzed. Present and future water availability under different environmental scenarios at various locations in the watershed was considered. Rice Equivalent Production from the watershed was found to improve by 207% (to 919 tonnes) and Rice Equivalent Yield by 58% (to 4427 kg ha⁻¹) through optimal allocation of available water resource. Occurrence of drought of 60% intensity would limit production to 737 tonnes. Environmental degradation by 2025 would though reduce production marginally, the surplus water available within the watershed would, however, decrease significantly during January to March. Future competition for water would adversely affect economy of the watershed and the region. The government should, therefore, undertake water resource development programmes after making a proper inventory of available resources at watershed level by analyzing the current and future supply and demand scenarios.

Understanding the complexity and feedbacks among food, energy, and water (FEW) systems is key to making informed decisions about sustainable development. This paper presents qualitative representation and quantitative system dynamics simulation of the water resources system in the Qazvin Plain, Iran, taking into account the energy intensity of water supply and interconnected water use sectors (e.g., urban, industrial, and agricultural). Qazvin Plain faces water resources challenges that are common to arid/semi-arid areas, including frequent droughts, declining surface water and groundwater, and increased urban and agricultural water demand. A system dynamics model is developed using historical data (2006–2016) to investigate the effects of anticipated dynamics of integrated water and energy sectors in the next two decades. The results of policy scenarios (2020–2039) demonstrate that the continuation of the existing management policies will cause severe damage to the water and energy sectors, pushing the system towards water resources limits to growth. An annual groundwater table decline of nearly 1 m is anticipated, indicating significant overshoot of the plain's natural recharge capacity, which may lead to the depletion of recoverable groundwater in the plain within the next three decades. The groundwater table decline will cause energy consumption of water supply to increase by about 32% (i.e., 380 GWh) to maintain irrigated agriculture. It is critical to implement a combination of water demand and supply management policies (e.g., net agricultural water savings and recycling treated wastewater) to delay the problem of water limits to growth in the region.

Water resources and food are the most important and basic resources for human beings and society. In recent decades, due to the growth of global population and economy, water resources and food shortages have become a global resource problem. Under this background, the significance of exploring the relationship between water-food in ecosystem services becomes more and more prominent. In view of this, this study used the SWAT model and the spatialized food production model to quantitatively evaluate the supply, demand, and supply-demand ratio of water and food production in the Jinghe River Basin in 2020, and built a system dynamics model of the watershed ecosystem services to simulate the coupling of water and food. According to the socio-economic conditions, nine different population economic development scenarios were set up to simulate the development of the water-food relationship between the ecosystem services of the river basin in 2030. The results showed that ① the spatial differences in water supply-demand ratio and food self-sufficiency rate in Jinghe River Basin in 2020 were obvious, and the supply-demand ratio in the upper reaches of the basin was significantly higher than that in the lower reaches. ② Through model simulations of three water supply-demand ratios and three food self-sufficiency rates, it was found that the water supply-demand ratios and food self-sufficiency rates showed obvious synergistic relationships both in time and in spatial distribution. ③ Under nine economic and demographic development scenarios, the optimal simulation effect was achieved under scenario E1P3 for both water-food supply and demand in the Jinghe River Basin in 2030. That was, when the economy and population develop in opposite directions, the supply-demand ratio of the two achieved the best simulation effect. The results provided a scientific basis for the sustainable development of water-food relationship in Jinghe River Basin in the future.

The safety of the water–energy–food (WEF) system in the China–Pakistan Economic Corridor (CPEC) is critical to the sustainable development of resources, the economy, and society in the region. This paper uses the projection pursuit model of a real-code accelerated genetic algorithm (RAGA-PP) to comprehensively evaluate the WEF system security of the CPEC for the period 2000–2016. The results show that from 2000 to 2016, the projection value of the WEF system was reduced from 2.61 to 0.53, and the overall system security showed a downward trend. Moreover, the CPEC increased by 6.13 × 10⁷ people, resulting in a rapid decrease in per capita water resources and decreased security of the water resources subsystem. With the rising social and economic development in recent years, the per capita energy consumption has likewise risen, leading to a decline in the energy subsystem. At the same time, the per capita grain output in the study area has increased from 185 to 205 kg, and the safety of the food subsystem has been enhanced. However, the significant increase in irrigated areas (from 1.82 × 10¹⁰ to 1.93 × 10¹⁰ hectares) has further highlighted the contradiction between the supply and demand of surface water resources, and the number of tube wells increased by 7.23 × 10⁵, resulting in the consumption of a large amount of electricity and diesel resources. The water–energy (WE) subsystem also became less safe. With the implementation of water resources management policies over the past few decades, the proportion of agricultural water consumption dropped from 95.06% in 2000 to 93.97% in 2016, and the safety of the water–food (WF) subsystem increased. Unfortunately, agricultural irrigation consumes a large amount of power resources, leading to a reduction in the security of the energy–food (EF) subsystem. The research results from the present study could provide a scientific basis for the coordinated development of WEF systems across the CPEC region.