In the past several decades, the irrigation of high-intensity cropping systems has caused serious groundwater depletion in the Beijing–Tianjin–Hebei region. Optimizing the planting structure is a key method for mitigating groundwater decline. However, the optimal planting structure has not been confirmed, and the effect of planting structures has not been quantified in groundwater overdraft areas. In this study, based on a model for planting structure optimization and the elitist nondominated sorting genetic algorithm, the water saving potential was estimated, and the trade-off between water resources and agricultural production was quantified. The results showed the following: (1) The current planting structure is a highly water-consuming system. The winter wheat–summer maize double-cropping system and vegetable and fruit cropping systems are the dominant contributors to crop water consumption, accounting for 90% of the total water deficit. (2) Constrained by regional water resources, it is difficult to achieve the objectives of halting groundwater decline and food self-sufficiency simultaneously unless at least 1.0 billion m³ yr⁻¹ water from the mid-route of the South-to-North Water Transfer (SNWT) project is used for agriculture or wheat imports account for more than 25% (2.84 million ton yr⁻¹) of the regional wheat demand. (3) It is almost impossible to achieve a balance between groundwater exploitation and replenishment only by optimizing the planting structure without decreasing the agricultural output or without using external water. When the planting structure is optimized, to coordinate grain crops, cash crops and water use, at least 81–96% (4.6–5.5 billion m³ yr⁻¹) of the planned water from the SNWT project will need to be used for agriculture. (4) A viable option for restructuring planting should consider the regional self-sufficiency for wheat, a moderate surplus of vegetables/fruits to boost farmers’ income, and appropriate water transfer for groundwater sustainability. The results provide a compromise between food and water in severe groundwater overdraft areas and serve as a quantitative reference for making decisions regarding agricultural and water resource policies.

The winter wheat–summer maize double cropping system caused overexploitation of groundwater in the North China Plain; it is unsustainable and threatens food security and the overall wellbeing of humankind in the region. Finding water-saving cropping systems without compromising food security is a more likely solution. In this study, six alternative cropping systems’ water conservation and food supply capacity were compared simultaneously. A combined water footprint method was applied to analyze the cropping systems’ water consumption. The winter wheat–summer maize system had the largest water consumption (16,585 m³/ha on average), followed by the potato/spring maize, spinach–spring maize, rye–spring maize, vetch–spring maize, pea/spring maize, soybean||spring maize and mono-spring maize cropping systems. For the groundwater, the spinach–spring maize, pea/spring maize, soybean||spring maize systems showed a higher degree of synchronization between crop growth period and rainfall, which could reduce use of groundwater by 36.8%, 54.4% and 57.6%, respectively. For food supply capacity, the values for spinach–spring maize, pea/spring maize, soybean||spring maize systems were 73.0%, 60.8% and 48.4% of winter wheat–summer maize, respectively, but they showed a better feeding efficiency than the winter wheat–summer maize system. On the whole, spinach–spring maize may be a good option to prevent further decline in groundwater level and to ensure food security in a sustainable way.

Understanding the interconnections and tradeoffs between food, energy, and water (FEW) in grain production, which are essential for agricultural sustainability, remains an elusive yet important task. We propose a four-step analysis method for exploring potential approaches to coordinating the FEW nexus in grain production based on a conceptual framework that incorporates the impact of rural livelihood transitions and farmland resource constraints. We apply this method to a small-scale watershed in Hunan Province, China using data from land-use maps, farm household surveys, farmland quality surveys, and cropping-pattern surveys. Transitions of rural livelihoods have led farmlands to become increasingly large in scale. The combined impacts of this concentration of large-scale farms and the government subsidy policy, which favors double cropping, undermines the FEW nexus. Our findings suggest two operational approaches for coordinating the FEW nexus in rice production. One is to develop adaptive agricultural policies that support farmers whose aggregate performance on rice production is superior or more balanced. The other is to optimize cropping patterns based on the suitability of farmland for grain planting.