Spatially optimized allocation of water and land resources based on multi-dimensional coupling of water quantity, quality, efficiency, carbon, food, and ecology

The research on optimizing agricultural water and land resources is significant for improving resource utilization efficiency, ensuring food security, protecting the ecological environment, and promoting sustainable economic development. However, few studies have been conducted on the spatially optimized allocation of water and land resources based on the multidimensional coupling of water quantity, water quality, efficiency, carbon, ecology, and food. Therefore, this study establishes the Coupling Optimization Model of Water Resources and Landscape Structure (COM-WL). The objective is to optimize resource allocation within the irrigation area by comprehensively considering multiple factors. The COM-WL model integrates our improved genetic algorithm, PAEA-NSGAⅢ, with the landscape allocation model, GridLOpt. PAEA-NSGAⅢ builds upon the traditional NSGA-III algorithm, incorporating a progressive fitness adjustment strategy along with an elite preservation strategy. These enhancements enable the algorithm to explore the solution space more efficiently when addressing complex multi-objective problems to validate the effectiveness and practicality of the COM-WL model, we selected the Daan Irrigation District as the study area. Twenty-four scenarios, spanning four hydrological years, were designed for analysis. Each scenario focuses on six optimization objectives: increasing carbon sequestration, improving irrigation efficiency, enhancing ecological benefits, ensuring food production, reducing groundwater extraction, and controlling pollutant emissions. The GridLOpt model enables grid-based layout and spatial allocation of landscape structure in optimized scenarios, improving ecological connectivity and controlling the costs associated with landscape changes. The optimization results indicate that the irrigated area of rice increased by 0.04–6.08 %, while the irrigated area for corn decreased by 6.20–0.02 %, with the overall irrigated area remaining relatively stable. Additionally, emissions of agricultural pollutants decreased by 1.95 %, reaching 4.52 %. Meanwhile, carbon sequestration increased by 0.01 %, reaching 0.59 %. The efficiency of crop water resource utilization improved by 2.05 %, reaching 4.08 %. Ecological connectivity rose by 11.6 %, reaching 20.3 %. Furthermore, land-use conversion costs ranged from 58.82 million to 207.97 million yuan, consistent with the expected landscape structure. The model established in this study provides an approach to the multidimensional optimization of the coupling between water and land resources.