Zhao et al. (2026) Quantifying the drivers of river thermal regimes in the Hanjiang River Basin under climate change and reservoir construction

Identification

• Journal: Journal of Hydrology
• Year: 2026
• Date: 2026-02-19
• Authors: Lei Zhao, Yuankun Wang, Yang You, Sen Wang, Yixu Wang, Changqing Meng, Yanke Zhang, Dong Wang, Dong Wang
• DOI: 10.1016/j.jhydrol.2026.135164

Research Groups

• School of Water Resources and Hydropower Engineering, North China Electric Power University, Beijing, PR China
• Key Laboratory of Surficial Geochemistry, Ministry of Education, Department of Hydrosciences, School of Earth Sciences and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing University, Nanjing, PR China

Short Summary

This study developed an integrated SWAT-HHO-LSTM modeling framework to disentangle the impacts of climate change and dam-heightening on river water temperature in the Hanjiang River Basin, revealing a spatial transition from dam-dominated cooling upstream to climate-driven warming downstream.

Objective

• To quantify and attribute the respective impacts of climate change and dam-heightening on long-term river water temperature variations across temporal and spatial scales in the Hanjiang River Basin.

Study Configuration

• Spatial Scale: Downstream reaches of the Danjiangkou Reservoir on the Hanjiang River, Hanjiang River Basin.
• Temporal Scale: Long-term variations, including historical periods and future projections (2076–2099) under multi-scenario climate projections (e.g., SSP585).

Methodology and Data

• Models used: SWAT (Soil and Water Assessment Tool), HHO-LSTM (Harris Hawks Optimization-enhanced Long Short-Term Memory network).
• Data sources: Multi-scenario climate projections from CMIP6 (Coupled Model Intercomparison Project Phase 6).

Main Results

• The HHO-LSTM model outperformed traditional LSTM, achieving RMSE reductions ranging from 2.5% to 36.7% across five stations.
• River water temperature (RWT) variations showed a temporal intensification of climate impacts and a spatial transition of dominant drivers.
• Temporally, climate change gradually became the primary driver of downstream warming, projected to account for up to 83% of RWT variation in some downstream regions during 2076–2099 under the SSP585 scenario.
• Spatially, the cooling influence of the dam progressively weakened along the river course.
• Near the dam (e.g., HuangJG), historical summer temperatures dropped by up to 7.07 °C and are projected to decline by more than 10 °C under SSP585, with peak temperatures delayed by as much as 65 days, primarily driven by dam-heightening (explaining over 90% of variability).
• Further downstream (XiangY, HuangZ, XianT), dam effects diminished, and climate change became the primary controlling factor, contributing approximately 66–84% of total RWT variation in the far-future period under SSP585.

Contributions

• Development of an integrated SWAT-HHO-LSTM modeling framework for robust attribution analysis of river water temperature drivers.
• Quantification of the distinct and evolving impacts of climate change and dam-heightening on river thermal regimes.
• Identification of a significant spatial transition in the dominant drivers of river water temperature, from dam-dominated regulation upstream to climate-driven warming downstream.
• Provision of crucial insights for developing adaptive strategies to manage thermal regimes in regulated rivers under future climate and anthropogenic changes.

Funding

• Not specified in the provided text.

Citation

@article{Zhao2026Quantifying,
  author = {Zhao, Lei and Wang, Yuankun and You, Yang and Wang, Sen and Wang, Yixu and Meng, Changqing and Zhang, Yanke and Wang, Dong and Zhang, Yanke and Wang, Dong},
  title = {Quantifying the drivers of river thermal regimes in the Hanjiang River Basin under climate change and reservoir construction},
  journal = {Journal of Hydrology},
  year = {2026},
  doi = {10.1016/j.jhydrol.2026.135164},
  url = {https://doi.org/10.1016/j.jhydrol.2026.135164}
}