Coupling optimization of irrigation and fertilizer for synergic development of economy-resource-environment: A generalized inexact quadratic multi-objective programming

Water and nutrients are two of the most important factors affecting agricultural production in arid regions, however, the misuse of agricultural chemicals has led to serious pollution. In order to achieve synergic regional economy-resource-environment development, this study proposes a generalized interval quadratic multi-objective programming model with fuzzy-interval credibility constraints (FIC-GIQMP). By introducing interval water-fertilizer production function, the quantitative relationship between crop yield, and evapotranspiration-fertilizer can be accurately reflected. The model can seek a balance among economic growth, resources security, and environmental pollution reduction, as well as address complexities, uncertainties, and risks by water-fertilizer management. Moreover, a modified duality-based algorithm is introduced to overcome the difficulty of solving the FIC-GIQMP model. The developed framework was applied to Shiyang River Basin in Northwest China. Optimal water and fertilizer allocations among different crops within each period under different scenarios were generated. Compared to the status quo, the optimal net benefit increased by 17.89%, while the carbon and water footprints decreased by 47.99% and 32.11%, respectively. Apart from giving the coupled water-fertilizer allocation schemes, the optimal results further appeal for decision-makers to modify irrigation pattern and crop structures.