Multi-objective optimal allocation of agricultural water and land resources in the Yellow River Basin: Coupling of quantitative structure and spatial allocation

Agricultural water and land resource optimization is fundamental to food security and regional sustainable development. However, under the Water-Energy-Food Nexus, conflicts among water, energy, and grain production have become increasingly prominent. These conflicts make multi-objective coordination difficult. Moreover, existing studies often lack spatial optimization, which limits the applicability of regional allocation schemes. To address these challenges, this study takes the Yellow River Basin as the study area and integrates the NSGA-III, the MaxEnt model, and a spatial allocation model to construct a multi-objective optimization framework that couples quantitative structure with spatial layout, aiming to achieve spatial optimization of agricultural water and land resources in large-scale grain-producing regions. Results show that: (1) Under water-saving scenario, the Northern Arid and Semi-arid Region (NAR) shows strong adaptability, with wheat, maize, and soybean increasing by 5.62%-16.04%; under energy-saving scenario, soybean area expands across entire basin, with the largest increase of 19.84% in the Huang-Huai-Hai Plain Region (HHHPR); under economic benefit scenario, NAR and HHHPR demonstrate strong production potential; under coordinated development scenario, all crop areas in the Sichuan Basin Region (SBR) decrease. (2) The coordinated development scenario breaks the trade-off between resource conservation and economic benefits observed in single-objective scenarios. Compared with the 2022 baseline, it reduces agricultural water consumption by 15.33%, cuts energy use by 8%, and increases economic benefits by 4%. (3) Spatial pattern changes are characterized by alternating shifts of maize-soybean and wheat-maize in NAR; active conversions among multiple crops occur in SBR, HHHPR, and the Han River Valley of the Loess Plateau Region, while the planting pattern in the Qinghai-Tibet Plateau Region remains stable. The framework can serve as a methodological reference for other regions facing similar agricultural planning challenges.