Feng et al. (2026) Spatiotemporal response of depth‑to‑water table (ZWT) to the Three Gorges Reservoir impoundment across hydrological year types

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2026
• Date: 2026-03-25
• Authors: Jinping Feng, Wenquan Gu, Shu Chen, M. Li, Donghao Miao, Dongguo Shao
• DOI: 10.1016/j.ejrh.2026.103344

Research Groups

• State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan, Hubei, China
• Water Resources Department, Changjiang River Scientific Research Institute, Wuhan, China
• Hubei Key Laboratory of River Basin Water Resources and Ecological Environment Science, Wuhan, China
• Xishuangbanna Dai Autonomous Prefecture Large-Scale Irrigation District Management Center, Xishuangbanna, Yunnan, China

Short Summary

This study quantifies the spatiotemporal response of depth-to-water table (ZWT) to the Three Gorges Reservoir (TGR) impoundment across hydrological year types in the Jianghan Plain. It finds that TGR impoundment leads to a general deepening of ZWT, with the strongest and most coherent response observed in wet years, concentrating in a narrow corridor near the Yangtze River.

Objective

• To quantify the spatiotemporal response of depth-to-water table (ZWT) to the Three Gorges Reservoir (TGR) impoundment.
• To assess how the ZWT response varies across hydrological year types (wet, normal, and dry).
• To analyze how trends and statistical distributions of groundwater depth shift from pre- to post-impoundment.
• To investigate how interannual spatiotemporal responses vary across hydrological year types.
• To determine how intra-annual (seasonal) spatiotemporal responses differ across these year types.

Study Configuration

• Spatial Scale: The Jianghan Plain, specifically the downstream acute-angle interfluve sector between the Yangtze River and its largest tributary, the Hanjiang River (Yangtze–Han interfluve wedge). The model used a 0.05° regional configuration over a computational domain spanning 28°–34°N and 108°–117°E.
• Temporal Scale: Simulations covered 1979–2018, with 1979–1989 as a warm-up period. The analysis focused on 1990–2018, comparing pre-impoundment (1990–June 2003) and post-impoundment (July 2003–2018) periods. A significant changepoint was detected in April 2005.

Methodology and Data

• Models used: Community Earth System Model version 2 (CESM2) coupled with the Community Land Model version 5 (CLM5) and the Model for Scale Adaptive River Transport (MOSART).
• Data sources:
  • Meteorological forcing: China Meteorological Forcing Dataset (CMFD) (3-hourly, 0.1° resolution, bilinearly resampled to 0.05°).
  • Crop structure: ChinaCropPhen1 km v7 (2000–2019) and ChinaCropArea1 km v3 (2000–2019).
  • Land use/vegetation: China Land-Use/Cover Change (CNLUCC) dataset (9 epochs from 1980 to 2020) and the 1:1,000,000 Vegetation Map of China (VMC1M).
  • Soil and subsurface properties: CSDLv2 (0–2 m), CSDHv1 (0–1.383 m, Clapp–Hornberger parameters), and the 100-m Bedrock Depth Map of China (CDTB100).
  • River routing: Global hydrotopographic dataset of Li et al. (2015) at 0.125° (conservatively remapped to 0.05°).
  • Validation data: Chinese Ecosystem Research Network (CERN) groundwater-level dataset (2005–2014).
  • Hydrological year classification: Annual runoff at the Yichang hydrological station (1990–2018) using a standardized runoff-anomaly approach.

Main Results

• The model accurately reproduces observed ZWT variability (Pearson correlation coefficient r = 0.767, coefficient of determination R² = 0.505, root-mean-square error RMSE = 0.126 m, percentage difference in spatial distribution PDD = 5.431%).
• A statistically significant changepoint in ZWT was detected in April 2005, approximately 22 months after the initial TGR impoundment, indicating a lagged system adjustment.
• The long-term ZWT decline (deepening) weakened after impoundment, with Sen’s slope reducing from -0.0615 m yr⁻¹ to -0.0561 m yr⁻¹ (an 8.78% reduction in decline magnitude).
• Regionally, the mean ZWT deepened by approximately 0.43 m relative to the pre-2005 baseline after the changepoint, corresponding to a cumulative 0.84 m water-table rise (decrease in ZWT) along the near-Yangtze corridor over 2004–2018.
• Post-impoundment, the ZWT distribution shifted towards deeper water tables, with reduced dispersion, abated left-skewness, and strengthened kurtosis (overlap coefficient = 0.77, indicating 23.18% non-overlap).
• Hydrological year type strongly modulates the response:
  • Wet years showed the largest deepening (0.87 m regional mean), largest affected area (99.5% significant pixels), and strongest seasonal-amplitude contraction (0.90 m), with pronounced deepening in summer–autumn.
  • Dry years showed a regional mean deepening of 0.31 m, with salient spring deepening (+0.65 m) and near-neutral autumn responses.
  • Normal years showed the smallest regional mean deepening of 0.26 m.
• Spatially, ZWT deepening organized into a narrow corridor near the Yangtze River (112.78°–113.12°E / 29.48°–29.62°N), while localized shallowing clusters occurred in the northern/northwestern plain (111.88°–112.03°E / 30.38°–30.88°N).

Contributions

• This study provides the first systematic appraisal of groundwater-depth patterns before and after TGR impoundment, resolved across inter- and intra-annual scales and stratified by hydrological year type (wet, normal, dry).
• It implements a high-resolution (0.05°) CESM2–CLM5–MOSART regional configuration driven by curated China-specific crop/land-use/soil–bedrock datasets to generate a spatially continuous, multi-decadal ZWT field for the Jianghan Plain.
• It delineates and quantifies coherent near-Yangtze nearshore-band dynamics (a response corridor) and peripheral localized shallowing clusters, interpreting these patterns through river–lake–aquifer connectivity under regulated-flow processes.
• The findings highlight that regulated-flow impacts on groundwater are not uniform in space or climate state, supporting targeted monitoring and groundwater-risk zoning for the Jianghan Plain and other downstream alluvial plains.

Funding

• National Natural Science Foundation of China (Grant No. U21A20156).

Citation

@article{Feng2026Spatiotemporal,
  author = {Feng, Jinping and Gu, Wenquan and Chen, Shu and Li, M. and Miao, Donghao and Shao, Dongguo},
  title = {Spatiotemporal response of depth‑to‑water table (ZWT) to the Three Gorges Reservoir impoundment across hydrological year types},
  journal = {Journal of Hydrology Regional Studies},
  year = {2026},
  doi = {10.1016/j.ejrh.2026.103344},
  url = {https://doi.org/10.1016/j.ejrh.2026.103344}
}