Zou et al. (2026) Impacts of climate and land use changes on water retention in the transboundary Yuanjiang-Red River Basin: Historical attribution and future projections

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2026
• Date: 2026-09-21
• Authors: Yi Zou, Roberto Ranzi, Xuan Ji, Paolo Colosio, Nguyen Hao Quang, Xuan Luo, Fan Zhou, Jianxing Li, Yungang Li
• DOI: 10.1016/j.ejrh.2026.104001

Research Groups

• Institute of International Rivers and Eco-security, Yunnan Key Laboratory of International Rivers and Transboundary Eco-security, Yunnan University, Kunming, China
• Department of Civil, Environmental, Architectural Engineering and Mathematics, Universit`a degli Studi di Brescia, Brescia, Italy
• Laboratory of Environmental Sciences and Climate Change, Institute for Computational Science and Artificial Intelligence, Van Lang University, Ho Chi Minh City, Viet Nam
• Faculty of Environment, Van Lang School of Technology, Van Lang University, Ho Chi Minh City, Viet Nam
• Ministry of Education Key Laboratory for Transboundary Eco-security of Southwest China, Yunnan University, Kunming, China

Short Summary

This study quantifies the historical drivers and projects future changes in water retention (WR) in the transboundary Yuanjiang–Red River Basin (YRRB) under climate and land-use changes. It finds that historical WR declined by 18 mm decade⁻¹ primarily due to climate change, and future WR is projected to decline by 29.6%–33.5% with increased spatial heterogeneity.

Objective

• To characterize the spatiotemporal evolution and long-term trends of water retention (WR) across the whole basin and six sub-basins during 1973–2015.
• To quantify the relative contributions of climate and land-use changes to WR at both the whole-basin and individual sub-basin scales.
• To project WR under three Shared Socioeconomic Pathway (SSP) scenarios for 2016–2050 and identify its dominant spatial patterns and corresponding temporal variations.

Study Configuration

• Spatial Scale: Yuanjiang–Red River Basin (YRRB), Southeast Asia, spanning approximately 156,451 km², delineated into six sub-basins. Model simulations were conducted at a 0.25° × 0.25° resolution.
• Temporal Scale: Historical attribution for 1973–2015; future projections for 2016–2050.

Methodology and Data

• Models used:
  • Variable Infiltration Capacity (VIC) model for hydrological simulation.
  • Bayesian Model Averaging (BMA) for integrating multi-model climate projections.
  • Empirical Orthogonal Function (EOF) analysis for identifying dominant spatial patterns of WR variability.
  • Quantile Delta Mapping (QDM) for bias correction of climate model outputs.
• Data sources:
  • Observed Runoff: Monthly runoff data from six hydrological stations in China and Vietnam.
  • Historical Meteorological Forcing (1973–2015): APHRODITE daily precipitation dataset; Princeton Global Meteorological Forcing (PGF) dataset for maximum/minimum temperature and wind speed.
  • Future Meteorological Forcing (2016–2050): Downscaled projections from five Coupled Model Intercomparison Project Phase 6 (CMIP6) Global Climate Models (ACCESS-CM2, BCC-CSM2-MR, EC-Earth3, GFDL-ESM4, MIROC6) from the NEX-GDDP-CMIP6 dataset, under SSP126, SSP245, and SSP585 scenarios.
  • Spatial Data: Digital Elevation Model (DEM); historical (1993, 2015) and projected (2030) Land-Use/Land-Cover (LULC) data.
  • Evapotranspiration (ET) Comparison Data: GLEAM4, TerraClimate, and SiTHv2 datasets.

Main Results

• Historical WR Trends (1973–2015): Mean historical WR averaged 572 mm and showed a non-significant decline of 18 mm decade⁻¹ across the basin. Declines were weaker in upper sub-basins (-1 to -13 mm decade⁻¹) and stronger in downstream sub-basins (-18 to -29 mm decade⁻¹).
• Historical Attribution: The basin-wide WR decline was primarily attributable to climate change (103.83% contribution rate), offsetting a modest mitigating effect from land-use change (-3.83%). Local buffering effects from land-use change were observed in some upstream sub-basins (e.g., sub-basin II with a 1.82 mm WR increase), but were insufficient to reverse the basin-wide decline.
• Future WR Projections (2016–2050): Basin-mean WR is consistently projected to decline by 29.6%–33.5% across the three SSP scenarios. This is driven by a slight projected decline in precipitation and a significant increase in evapotranspiration (31.4%–34.3%), leading to a substantial reduction in runoff (34.2%–37.2%).
• Spatial Heterogeneity: EOF analysis revealed a shift towards greater spatial heterogeneity in future WR. EOF1 (basin-wide monopolar pattern) explained 79% of variance under SSP126, but decreased to 64%–68% under SSP245 and SSP585. EOF2 (upstream–downstream dipole pattern) increased its explained variance from 7% to 12%–17% under SSP245 and SSP585, indicating reduced basin-wide coherence and enhanced regional differentiation. This shift is associated with the combined effects of declining precipitation and increasing evapotranspiration.

Contributions

• Provides an integrated assessment of both historical attribution and future projections of water retention (WR) in a transboundary river basin, addressing a gap in existing literature.
• Quantifies the relative contributions of climate change and land-use change to historical WR dynamics in the topographically complex Yuanjiang–Red River Basin (YRRB).
• Utilizes a robust multi-model coupled framework, integrating the VIC hydrological model, a fixed-varying scenario design, Bayesian model averaging of bias-corrected CMIP6 climate projections, and Empirical Orthogonal Function (EOF) analysis.
• Identifies scenario-dependent magnitudes and spatial patterns of future WR changes, highlighting increased spatial heterogeneity and the dominant role of atmospheric demand under intensified warming.
• Offers actionable insights for coordinated cross-border ecological restoration and spatially targeted water management strategies between China and Vietnam.

Funding

• Yunnan Fundamental Research Projects (grant No. 202503AP140045)
• China Scholarship Council

Citation

@article{Zou2026Impacts,
  author = {Zou, Yi and Ranzi, Roberto and Ji, Xuan and Colosio, Paolo and Quang, Nguyen Hao and Luo, Xuan and Zhou, Fan and Li, Jianxing and Li, Yungang},
  title = {Impacts of climate and land use changes on water retention in the transboundary Yuanjiang-Red River Basin: Historical attribution and future projections},
  journal = {Journal of Hydrology Regional Studies},
  year = {2026},
  doi = {10.1016/j.ejrh.2026.104001},
  url = {https://doi.org/10.1016/j.ejrh.2026.104001}
}