He et al. (2025) Event- and annual-scale precipitation extremes enhance groundwater recharge at the ecological restoration catchment of hilly and gully region

Identification

• Journal: Ecological Engineering
• Year: 2025
• Date: 2025-12-05
• Authors: Meina He, Yunqiang Wang, Yali Zhao, Li Wang, Ziliang Zhang, Yi Song, Pingping Zhang, Zimin Li
• DOI: 10.1016/j.ecoleng.2025.107868

Research Groups

• State Key Laboratory of Loess Science, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an, Shaanxi 710061, China
• School of Ecology and Environment, Northwestern Polytechnical University, Xi’an, Shaanxi 710129, China
• Department of Earth and Environmental Sciences, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
• National Observation and Research Station of Earth Critical Zone on the Loess Plateau of Shaanxi, Xi’an 710061, China
• College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China

Short Summary

This study investigated how precipitation extremes and ecological restoration influence groundwater recharge in a Chinese Loess Plateau catchment, finding that both event- and annual-scale extreme precipitation significantly enhance deep groundwater recharge, particularly through preferential flow pathways.

Objective

• To analyze the influence of precipitation extremes and ecological restoration projects on hydrological processes, specifically groundwater recharge, within an ecological restoration catchment on the Chinese Loess Plateau.
• To determine how deep recharge depends on unsaturated zone thickness and precipitation event magnitude.

Study Configuration

• Spatial Scale: Meina He ecological restoration catchment, hilly and gully region of the Chinese Loess Plateau.
• Temporal Scale: Seven-year field dataset analysis.

Methodology and Data

• Models used: Not explicitly mentioned; analysis based on field observations.
• Data sources: Seven-year field datasets including precipitation, soil water content (SWC), surface water (reservoir water), and groundwater (water table, δ18O).

Main Results

• Precipitation extremes triggered deep hydraulic connectivity between unsaturated and saturated zones, primarily via preferential flow pathways, evidenced by depleted δ18O, increased SWC profiles, and rising water tables.
• Preferential flow pathways were observed on sunny slopes, with recharge efficiency regulated by precipitation patterns and topography.
• In gullies, water tables showed positive correlations with precipitation amount, duration, and initial SWC, leading to significant differences in water table changes across precipitation years.
• Slopes (0–500 cm profile) generally maintained persistent water deficits with limited recharge response, except for a 167.7 mm precipitation event.
• The 200–300 cm soil layer functioned as a hydraulic buffer due to precipitation variability coupled with plant root uptake.
• Prolonged drought accelerated water table recession at 60.8 mm/year and created carry-over soil water deficits, sustaining a 15.4 mm/year depletion even in the subsequent normal year.
• Total recharge rates demonstrated positive hydrological feedback of ecological restoration projects to annual precipitation, accounting for 45% of precipitation (327.8 mm/year) during a wet year.

Contributions

• Provides scientific evidence for the role of precipitation extremes in enhancing groundwater recharge in ecologically restored catchments, addressing a gap in understanding deep recharge dependence on unsaturated zone thickness and precipitation event magnitude.
• Highlights the importance of preferential flow pathways and topographic influences on recharge efficiency in such systems.
• Quantifies the impact of drought on water table recession and carry-over soil water deficits, and the positive feedback of ecological restoration on annual recharge.

Funding

• Not explicitly mentioned in the provided text.

Citation

@article{He2025Event,
  author = {He, Meina and Wang, Yunqiang and Zhao, Yali and Wang, Li and Zhang, Ziliang and Song, Yi and Zhang, Pingping and Li, Zimin},
  title = {Event- and annual-scale precipitation extremes enhance groundwater recharge at the ecological restoration catchment of hilly and gully region},
  journal = {Ecological Engineering},
  year = {2025},
  doi = {10.1016/j.ecoleng.2025.107868},
  url = {https://doi.org/10.1016/j.ecoleng.2025.107868}
}