From land subsidence to sustainability: Strategic mining and reclamation scenarios for coal-grain overlapping areas

Abstract Land subsidence induced by underground coal mining consistently leads to persistent ponding in coal-grain overlapping areas (COAs), substantially impairing agricultural productivity. However, amid stringent farmland protection policies, mining operations face significant sustainability challenges. In this study, Guqiao Coal Mine in Anhui of China, is taken as a case, and four mining-reclamation schemes were conducted to compare patterns, and applicable conditions for each scheme are proposed based on concurrent mining and reclamation (CMR). Results show that: (1) Historically, traditional mining-reclamation (TMR) dominated due to low immediate reclamation costs despite extensive farmland loss; (2) Currently, earthwork-conserving CMR (ECMR) offers practical advantages by balancing economic investment and farmland reclamation. ECMR enhances land reclamation and reduces indirect costs, but leads to premature farmland degradation and prolonged compensation burdens; (3) Henceforth, reducing-degradation CMR (RCMR) can eliminate farmland degradation but is constrained by low coal-extraction rates, making it less feasible under current coal economic constraints; (4) In the prospective future, coupling CMR (CCMR) delays land degradation while improving reclamation efficiency, shortening the restoration cycle by 42% for ECMR, and raising coal-extraction rate to over 92% for RCMR. It restores 70% of degraded farmland and reduces seedling compensation costs by over 63 million yuan for ECMR in 30 years. CCMR also has strong performance in reducing surface ponding, maintaining grain security, and minimizing social displacement. Our findings underscore CCMR's superiority in aligning economic, ecological, and social objectives. It offers a replicable model for sustainable resource management in C1OAs globally, particularly under tightening environmental and agricultural policies.