Ren et al. (2026) Spatial heterogeneity and controlling mechanisms of multi-interface groundwater recharge in karst critical zone

Identification

• Journal: Journal of Hydrology
• Year: 2026
• Date: 2026-01-23
• Authors: Huimin Ren, Fa Wang, Hamid Behzad, Wenna Liu, Kelin Wang
• DOI: 10.1016/j.jhydrol.2026.134984

Research Groups

• Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan 410125, China
• Guangxi Key Laboratory of Karst Ecological Processes and Services, Huanjiang Observation and Research Station for Karst Ecosystems, Chinese Academy of Sciences, Huanjiang, Guangxi 547100, China
• University of Chinese Academy of Sciences, Beijing 100049, China

Short Summary

This study quantified the spatial variability and controlling mechanisms of multi-interface groundwater recharge in a karst critical zone, revealing a shift from topography-driven rapid processes in shallow aquifers to stable regulation by soil-rock structure in deeper aquifers.

Objective

• To quantify the spatial variability and controlling mechanisms of multi-interface groundwater recharge in a karst critical zone with high surface-subsurface heterogeneity.

Study Configuration

• Spatial Scale: Fourteen monitoring wells installed across a soil-covered slope (SH) and a rock-exposed slope (RH) at up, middle, down slope positions and a depression. Shallow aquifers were targeted at 2–11 meters depth, and deep aquifers at 11–60 meters depth.
• Temporal Scale: Hourly monitoring of rainfall and groundwater levels over a period sufficient to capture episodic and seasonal variations.

Methodology and Data

• Models used: Multiple statistical metrics (e.g., kurtosis, coefficient of variation, rainfall-groundwater coherence, response time, quick-flow proportion, memory time) and Partial Least Squares Regression (PLSR).
• Data sources: In-situ monitoring wells (groundwater levels) and rainfall gauges (rainfall).

Main Results

• Shallow groundwater exhibited higher kurtosis (217) and coefficient of variation (8.1) compared to deep groundwater (5.2 and 0.5, respectively), indicating sensitivity to episodic heavy rainfall for shallow aquifers and influence by seasonal rainfall for deep aquifers.
• Groundwater in both shallow and deep aquifers on rock-exposed slopes (RH) showed higher rainfall-groundwater coherence (0.4), shorter response times (23 hours), and greater quick-flow proportions (8 %) than on soil-covered slopes (SH).
• Lower recharge amounts (171 millimeters) and shorter memory times (338 hours) on RH were observed only in the shallow weathered layer, suggesting weaker hydrological regulation function on RH due to near-surface processes.
• Hydrological regulation function increased from upslope to downslope, with insignificant variation across SH but greater spatial variability on RH.
• Partial Least Squares Regression indicated that concave topography and high bedrock exposure promoted rapid recharge and discharge, explaining 85–98 % of hydrological variability in the shallow strongly weathered aquifer.
• High permeability and strong weathering delayed recharge and discharge processes, accounting for 65–83 % of variability in the deep weakly weathered aquifer.
• Groundwater recharge mechanisms shifted from topography-driven rapid processes in the shallow aquifer to stable regulation controlled by overlying soil-rock structure in the deep aquifer.

Contributions

• Provides a quantitative understanding of the spatial variability and controlling mechanisms of multi-interface groundwater recharge in complex karst critical zones.
• Highlights the shift in dominant recharge processes from topography-driven in shallow aquifers to soil-rock structure-controlled in deeper aquifers.
• Offers a scientific basis for developing sustainable groundwater management strategies in heterogeneous hydrogeological systems.

Funding

• Not specified in the provided text.

Citation

@article{Ren2026Spatial,
  author = {Ren, Huimin and Wang, Fa and Behzad, Hamid and Liu, Wenna and Wang, Kelin},
  title = {Spatial heterogeneity and controlling mechanisms of multi-interface groundwater recharge in karst critical zone},
  journal = {Journal of Hydrology},
  year = {2026},
  doi = {10.1016/j.jhydrol.2026.134984},
  url = {https://doi.org/10.1016/j.jhydrol.2026.134984}
}