Dynamic hydro-geomechanical modeling reveals coal mining-induced lake function inversion and intensified water scarcity in arid regions: A case study in the Nalinxili Coalfield, Yellow River Basin

Study region The Nalinxili Coalfield, situated in the ecologically fragile and water-stressed Yellow River Basin, experiences intensifying conflicts between underground coal extraction and groundwater-dependent lacustrine ecosystems, particularly Hadatu Naor Lake. Study focus This study develops and applies a dynamically coupled SWAT-MODFLOW-Mine framework to quantify the spatiotemporal evolution of mining-induced surface subsidence, hydraulic fracture zone (HFZ) permeability, and surface water-groundwater interactions, aiming to evaluate hydrological alterations, ecological thresholds, and adaptive management pathways. New hydrological insights Mining operations trigger a mechanistic hydrological reversal wherein Hadatu Naor Lake transitions from a groundwater-receiving system to a terminal discharge sink, driven by the upward propagation of the HFZ (28.71–116.35 m) that establishes a new deep seepage pathway ( Q ) of 5000–50,000 m³ /year. Concurrently, regional groundwater drawdown reduces lateral lake recharge by 24.6%, while subsidence (2.24–3.92 m) increases lake storage capacity by 4.5 million m³ , fundamentally altering bathymetry, thermal stratification, and littoral habitat connectivity. Despite an overall volumetric loss of < 1%, the system crosses a critical ecological threshold as the hydraulic gradient inversion disrupts natural groundwater-driven flushing mechanisms, amplifying shoreline capillary salinization and reducing drought resilience. These process-based dynamics demonstrate that hydrological pathway integrity, rather than absolute water volume, governs ecological stability in arid mining landscapes, providing a quantitative, threshold-driven basis for lake conservation and adaptive water governance. mine