Delineation of High-Standard Farmland Based on Urban Expansion Probability and Compactness: A Case Study of Guangzhou

Protecting high-standard farmland is pivotal for sustainable land utilization and long-term regional food security. However, delineating high-standard farmland in metropolitan areas often neglects the influences of future urban expansion and farmland morphology, critical factors for enhancing farmland productivity. To address this, this study established a systematic evaluation framework for high-standard farmland delineation. It employed the patch-generating land use simulation model to forecast the probability of future urban expansion while employing the analytic hierarchy process and entropy weight method to calculate combined weights for evaluating farmland suitability. An ant colony optimization algorithm was implemented to improve farmland suitability and morphological compactness, thereby scientifically delineating high-standard farmland. Results from Guangzhou reveal that farmland area decreased between 2000 and 2020, primarily driven by urban expansion. The delineated high-standard farmland covers 682.18 km2, achieving dual optimization of farmland suitability and compactness. The results are predominantly located within permanent basic farmland and grain production functional zones. This finding aligns with previous studies and existing plans, demonstrating the methodology’s superiority. Furthermore, this study categorizes Guangzhou’s high-standard farmland into four grades and proposes targeted policy recommendations. In summary, this study presents a new and scientific approach for high-standard farmland delineation, offering valuable policy support for sustainable farmland management.