A scenario-based type-2 fuzzy interval programming approach for planning mid-and-long term regional-scale water-energy-food nexus system management under uncertainty

Water, energy and food are three strategic supporting elements for the sustainable development of national economy. With the continuous growth of population and economy, the challenge of ensuring adequate water, food and energy is intensifying. Water, energy and food have complex interactions, the three elements are not only interdependent but also interact and compete with each other, which makes the integration of water-energy-food become more complicated and uncertain. Many studies have separated and broken the nexus among the water, energy and food. Meanwhile, the traditional fuzzy programming method for managing uncertain water-energy-food nexus (WEFN) system can merely deal with fuzzy sets with deterministic membership functions while it is incapable of handling the uncertain fuzzy membership functions. Thus this study aims to address the uncertain fuzzy membership functions through introducing the type-2 fuzzy theory and deal with the complexities associated with nexus, intersect and dynamic information in terms of the interval parameter programming and scenario analysis. Then a type-2 fuzzy programming based WEFN coupling system is applied to the Henan Province, China. The modelling can generate comprehensive management schemes of the WEFN system, which can provide decision supports for the coordinated development of Henan Province among water, energy, food, economy and society as well as environment. Results indicate that when the system's water supply is insufficient, the system benefit will increase by adjusting the planting structure; conversely, sufficient water will be supplied to crops on the premise of coordinating the water demand of other departments and avoiding the waste of water resources. These findings can: a) address the contradictions among limited water resources, food security, energy demand, economic development and ecological environmental protection; b) realize the optimal allocation of land resources, efficient utilization of water resources; and c) promote the sustainable development of regional agriculture.