Fuzzy multi-objective modelling for managing water-food-energy-climate change-land nexus towards sustainability

Water, food, energy, climate change and land subsystems are closely intertwined, and play remarkable roles in regional resources management system. Quantification of connections, synergies, and tradeoffs across these subsystems is needed in a more integrated and comprehensive manner, which is challenging due to the complexities and uncertainties involved therein. This paper proposed an inexact optimization approach from a novel water-food-energy-climate change-land (WORLD) nexus perspective, which has potential to promote social-economic development, guarantee livelihood security, and achieve low-carbon target. The approach is capable of (1) helping decision makers identify optimal policy alternatives among water, land, and energy, balancing economic benefit, water supply guarantee rate, hydroelectric generation, water-land utilization, crop yield, and greenhouse gas emission, via a multi-objective non-linear optimization model; (2) providing decision makers insights into in-depth analysis of optimal water-land resources allocation strategies associated with different levels of water supply, optimistic-pessimistic attitude, and climate change and where the effort could be made towards regional sustainability; (3) dealing with fuzzy uncertainties simultaneously occurring in objective functions and constraints as well as tracking fluctuating attitudes of decision-makers. The effectiveness of proposed model was verified in a real-world case in Zhanghe Irrigation District, Hubei Province, China. The changing range of economic benefit, crop yield, energy production, and environmental impacts were obtained based on optimal water-land resources allocation under different confidence levels and risk attitudes. Results under climate change scenarios show that climate change exacerbated local water shortage, especially in RCP 8.5, which requires 4.24 × 10⁸ m³ of compensatory external water. Results also show that CO₂ emission contributed 94.9% of GHGs emission, while fertilizers application contributed to 58% of total CO₂ emission amount, calling for effective fertilizer utilization management. Compared with single objective models, proposed model performs better on providing coordinated policy solutions. The proposed approach can help manage resources in WORLD nexus system in a sustainable way, and is portable to other similar regions to promote sustainable development.