Identification of potential target zones for groundwater reservoirs based on hydrogeological constraints

To reduce the dependence of regional groundwater-reservoir screening on subjective indicator weighting and empirical thresholds, a method for identifying potential groundwater target zones was developed. An identification framework integrating “data-driven zoning–hydrogeological constraints–ecological water-replenishment validation” was established for the shallow aquifer system of the Beijing–Tianjin–Hebei Plain. Eight hydrogeological indicators representing the water source, storage capacity, storage, and recharge conditions were selected. Probabilistic zoning was performed using clustering and maximum-likelihood classification. Constraints related to paleochannel deposits, landforms, and river networks were also incorporated to delineate potential target zones. Groundwater responses were then validated using ecological water-replenishment events, and characteristic storage capacities were estimated through Monte Carlo simulations. The framework identified eight potential target zones with a total area of 6097.9 km² and a maximum adjustable storage capacity of (4.16 ± 0.47) × 10⁹ m³. The Tanghe-Shahe and Hutuo River target zones together accounted for 69.2% of the total maximum adjustable storage capacity, and the mean groundwater level increased by 0.22 m during ecological water replenishment. Therefore, these two zones should be prioritized in subsequent groundwater-reservoir investigations. The proposed method provides a practical reference for preliminary groundwater-reservoir planning and identifying priority investigation areas.