Li et al. (2026) Long-term variations of hydrological connectivity and its drivers in the middle reach wetlands of the Yangtze River

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2026
• Date: 2026-01-06
• Authors: Pinjian Li, Haojun Xi, Qiqi Ding, Chuanzhe Feng, Yulong Yang, Fenglin Wang, Fulei Han, Tianhong Li
• DOI: 10.1016/j.ejrh.2025.103076

Research Groups

• College of Environmental Sciences and Engineering, Peking University, Beijing, China
• The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing, China

Short Summary

This study assessed the long-term (1993–2022) patterns and drivers of wetland hydrological connectivity in the Poyang Lake and Dongting Lake plains, revealing a significant decline in connectivity in Poyang Lake and identifying climate as the predominant driver, with critical water level thresholds of 9.8 m and 23.5 m for maintaining moderate or higher connectivity.

Objective

• To construct a comprehensive and scalable framework integrating landscape metrics and geostatistical methods for evaluating wetland hydrological connectivity.
• To quantify the spatiotemporal dynamics of hydrological connectivity across seasonal and interannual scales.
• To identify and disentangle the relative importance of natural and anthropogenic drivers using machine learning and structural equation modeling.
• To evaluate the response of hydrological connectivity to key drivers, particularly water level.

Study Configuration

• Spatial Scale: Poyang Lake Plain and Dongting Lake Plain, located in the middle reaches of the Yangtze River, China.
• Temporal Scale: Long-term analysis from 1993 to 2022.

Methodology and Data

• Models used:
  • Random Forest (RF) classifier for land cover classification and driver importance.
  • Pearson’s correlation analysis for initial driver relationships.
  • Partial Least Squares Structural Equation Modeling (PLS-SEM) for causal pathway analysis.
  • Copula-based analysis for joint distribution and conditional probability of hydrological connectivity and water level.
  • Mann-Kendall (MK) test and Sen’s Slope estimator for trend analysis.
  • Wilcoxon test for pre/post-Three Gorges Dam comparison.
  • FRAGSTATS software for morphological and structural landscape indices.
• Data sources:
  • Remote sensing: Landsat 5 TM, Landsat 7 ETM+, and Landsat 8 OLI satellite images (USGS/Google Earth Engine) for land cover classification (30 m spatial resolution, 16 days temporal resolution).
  • Climate data: 1 km monthly temperature, precipitation, and potential evapotranspiration datasets for China (1901–2023) (National Tibetan Plateau Data Center).
  • Hydrological data: Daily water level and water flow from the Yangtze River Basin Hydrological Database (Chenglingji Hydrological Station for Dongting Lake, Xingzi Hydrological Station for Poyang Lake).

Main Results

• Wetland hydrological connectivity in the Poyang Lake Plain showed a significant long-term decline (slope: -0.0045/year in dry season, -0.0057/year in wet season), while no consistent trend was observed in the Dongting Lake Plain.
• Both regions experienced marked reductions in connectivity following the operation of the Three Gorges Dam (post-2004), particularly during the wet season.
• Climate factors (precipitation, temperature) were the predominant drivers of hydrological connectivity changes across both plains, exerting the greatest total influence.
• Hydrological factors, especially water level, were identified as key contributors, being the dominant direct driver in the Dongting Lake Plain.
• Anthropogenic factors, primarily human-induced land use change (e.g., impervious surfaces), had a consistently negative impact on connectivity, accounting for less than 5 % of the total effect but acting as an amplifying stressor.
• Copula analysis identified critical water level thresholds: 9.8 m for Poyang Lake and 23.5 m for Dongting Lake are required to maintain moderate or higher hydrological connectivity.

Contributions

• Developed an integrated framework for assessing wetland hydrological connectivity by combining morphological, structural, and geo-functional dimensions, offering a comprehensive, multi-scale understanding beyond conventional single-aspect approaches.
• Quantified the long-term spatiotemporal dynamics of wetland hydrological connectivity in the middle Yangtze River wetlands, highlighting regional differences and the impact of the Three Gorges Dam.
• Identified and disentangled the relative importance and influence pathways of natural (climate, hydrology) and anthropogenic (land use, hydraulic infrastructure) drivers using advanced statistical modeling (RF, PLS-SEM).
• Determined critical ecological water level thresholds for maintaining wetland hydrological connectivity using Copula analysis, providing actionable guidance for region-specific wetland management and restoration strategies.

Funding

• The National Key Research and Development Program (2022YFC3201801)

Citation

@article{Li2026Longterm,
  author = {Li, Pinjian and Xi, Haojun and Ding, Qiqi and Feng, Chuanzhe and Yang, Yulong and Wang, Fenglin and Han, Fulei and Li, Tianhong},
  title = {Long-term variations of hydrological connectivity and its drivers in the middle reach wetlands of the Yangtze River},
  journal = {Journal of Hydrology Regional Studies},
  year = {2026},
  doi = {10.1016/j.ejrh.2025.103076},
  url = {https://doi.org/10.1016/j.ejrh.2025.103076}
}