Technology integration model and engineering innovation practices for green governance and utilization of coal mining subsidence areas with a high groundwater table

Approximately 2 million hectares of coal mining subsidence areas have formed in China, of which about one-third are permanently or seasonally waterlogged. Subsided cropland not only loses its grain production function but also gives rise to a series of ecological, environmental, and social problems, especially in mining areas with a high groundwater table. Using laboratory model simulations, in-situ experiments under different scenarios, space-air-ground-network integrated monitoring, and engineering applications, this study innovatively integrates green governance and utilization pathways and technical models for high-groundwater-table coal mining subsidence areas under the coordinated goals of energy and food security. The main innovations are as follows. The nitrogen and phosphorus cycling mechanisms under rice cultivation on subsided water surfaces were systematically revealed. The fluxes of nitrogen and phosphorus absorbed by rice from the water body were 77.5% and 62.7% higher, respectively, than the fluxes released from the substrate into the water body, thereby clarifying the internal mechanism of “rice-based water purification”. A complete set of key technologies and models for rice-fish co-culture and fishery-photovoltaic complementary utilization in waterlogged coal mining subsidence areas was established for the first time. A specialized substrate for floating cultivation on subsided water surfaces was developed to balance sustained nutrient supply and environmental control. An adaptive lifting device for floating planting plates based on a fixed-pulley and counterweight system was also developed, enabling free vertical adjustment under a maximum water-level fluctuation of 1.0 m. In addition, fully automated equipment integrating substrate cup filling and transplanting, as well as bank-side harvesting equipment, was invented. Floating photovoltaic layout schemes and optimized anchoring technologies were proposed. A governance pathway characterized by “dynamic restoration, integration of three types of planning, and three-category governance” was established. An ecological restoration and multifunctional utilization model was developed for grain-coal overlapping mining areas with a high groundwater table and was applied and demonstrated over an area exceeding 2.0 × 10⁷ m². An intelligent assessment and dual-terminal collaborative management and control platform for the soil-water environment in mining areas was established, forming a key technical chain of “soil-water environmental damage diagnosis, cropland productivity assessment, and multi-objective optimal regulation” under coal mining disturbance restoration scenarios. These findings fill the technical gap in the green governance and utilization of high-groundwater-table coal mining subsidence areas, and provide theoretical support and technical guidance for ecological restoration, cropland protection, and high-quality sustainable utilization of coal mining subsidence land in grain-coal overlapping regions.