Liang et al. (2026) Interactive driven force analysis of blue and green water for Yalong River Basin of southwest China based on a hybrid modeling approach

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2026
• Date: 2026-01-16
• Authors: Yanan Liang, Yanpeng Cai, Junjie Niu, Xuan Wang
• DOI: 10.1016/j.ejrh.2026.103133

Research Groups

• Research Center for Scientific Development in Fenhe River Basin, Taiyuan Normal University, Jinzhong, China
• Guangdong Provincial Key Laboratory of Water Quality Improvement and Ecological Restoration for Watersheds, Guangdong Basic Research Center of Excellence for Ecological Security and Green Development, School of Ecology, Environment and Resources, Guangdong University of Technology, Guangzhou, China
• Shanxi Key Laboratory of Earth Surface Processes and Resource Ecology Security in Fenhe River Basin, Taiyuan Normal University, Jinzhong, China
• State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, China

Short Summary

This study investigated the responses of blue and green water components to various climate factors and anthropogenic disturbances in the Yalong River Basin, southwest China, using a hybrid modeling approach. It found that climate change, particularly rising precipitation and temperature, is the dominant driver of increasing blue and green water trends, with land use/land cover changes having a minor effect, and these impacts intensifying over time.

Objective

• To detect blue-green water variation along with land use/land cover (LULC) and climate changes.
• To differentiate the effect of LULC and various climate factors on blue-green water at the subbasin scale relative to a baseline period.
• To quantify the contribution of various driven factors to blue-green water amounts.

Study Configuration

• Spatial Scale: Yalong River Basin (YLRB), southwest China (25°12′–34°9′N, 96°47′–102°42′E), with a drainage area of approximately 126,475.6 km². The basin was divided into 177 subbasins and 3530 hydrological response units (HRUs).
• Temporal Scale: The hydrological simulation period was 1967–2017. This period was divided into a baseline period (1967–1981), studying period 1 (P1: 1982–1996), and studying period 2 (P2: 1997–2017).

Methodology and Data

• Models used:
  • Soil and Water Assessment Tool (SWAT) hydrological model.
  • Detrend techniques (Mann-Kendall trend test) for meteorological data.
  • Sensitivity analysis and attribution techniques.
  • Target release approach for simulating reservoir operations.
• Data sources:
  • Digital Elevation Map (DEM) from SRTM (90 m spatial resolution).
  • Land Use/Land Cover (LULC) maps from Finer Resolution Observation and Monitoring of Global Land Cover (30 m spatial resolution) for the 1980s, 1995, and 2015.
  • Soil types from China Soil Map Based Harmonized World Soil Database (v1.1) (1 km spatial resolution).
  • Daily meteorological input data from China Meteorological Data Service Centre (precipitation, maximum and minimum temperatures, relative humidity, wind speed, solar radiation).
  • Monthly observed streamflow data (1979–1983, 2006–2010) at the basin outlet.
  • Remote sensing products for cross-validation: TerraClimate (evapotranspiration, soil moisture) and GLASS Leaf Area Index (LAI) product.
  • Information for four large artificial reservoirs (Jinping I, Guandi, Ertan, Tongzilin).

Main Results

• Overall Trends (1967–2017): Blue water, green water storage, and streamflow showed slight upward trends. Green water flow exhibited a significant upward trend of 6.35 mm per decade (p < 0.01). Annual precipitation increased by 14.2 mm per decade (p < 0.1). Average annual maximum and minimum temperatures significantly increased by 0.28 ℃ per decade and 0.35 ℃ per decade, respectively. Average annual solar radiation significantly decreased by -0.028 MJ⋅m⁻² per decade.
• Land Use/Land Cover (LULC) Impact: LULC changes generally exerted a slight effect on blue and green water, causing variations of -2 to 2 mm in most subbasins. Urban land area increased significantly (31.3% in P1, 203.1% in P2), while water area decreased substantially (-72.6% to -81.4%). LULC change slightly increased the average annual streamflow (1.4 m³/s in P1, 1.5 m³/s in P2).
• Climate Change Impact (Dominant Driver): The magnitude of blue and green water variations driven by climate change was generally greater than that driven by LULC, and these effects enhanced from P1 to P2.
  • Blue Water: Precipitation was the greatest contributor (48.83% in P1, 55.48% in P2), leading to increases of 5–25 mm in P1 and 25–80 mm in P2 in most subbasins, particularly in the upper and middle reaches. Rising temperatures caused negative changes in blue water in the warmer, water-constrained lower reaches (-80 to -10 mm in P1, -90 to -20 mm in P2), with its contribution rising from 4.22% in P1 to 22.99% in P2.
  • Streamflow: Climate change was the dominant driver of streamflow variation (75% in P1, 89% in P2), with its magnitude increasing from 21 m³/s in P1 to 53 m³/s in P2. Precipitation contributed the most (49% in P1, 55% in P2), leading to increases of 42 m³/s in P1 and 117 m³/s in P2. Temperature variations led to streamflow decreases of -11 m³/s in P1 and -58 m³/s in P2, with its contribution rising from 13% in P1 to 27% in P2.
  • Green Water Flow: Primarily increased due to temperature change (0–15 mm in P1, 2–30 mm in P2 in most subbasins). Declining solar radiation caused a decrease in green water flow (-2 to 0 mm in P1, -3 to 0 mm in P2).
  • Green Water Storage: Precipitation forced an increase (-0.4 to 3.1 mm in P1, -7.8 to 9.4 mm in P2), while temperature caused a negative variation, especially in P2 (-9.5 to 5.1 mm in P1, -13.1 to 7.6 mm in P2). Climate change led to a negative trend in green water storage in certain subbasins from P1 to P2 due to intensified warming.
• Reservoir Impact: Cascade reservoirs had a slight impact on the average annual streamflow compared to climate change but significantly regulated intra-annual streamflow, reducing it during the flood season (-1926 to -71 m³/s) and increasing it during the dry season (105 to 1487 m³/s).

Contributions

• Provided a refined attribution analysis by differentiating the individual and interactive effects of various climate factors (precipitation, temperature, relative humidity, solar radiation) and LULC changes on blue and green water components.
• Quantified the specific contributions of each climate factor to blue and green water variations, revealing that precipitation dominated blue water and green water storage increases, while temperature was the primary driver for green water flow increases.
• Highlighted the increasing severity of temperature impacts on hydrological processes, posing potential water resource crises.
• Demonstrated the significant spatial heterogeneity in blue and green water responses to climate factors, emphasizing the need for zone-specific climate adaptation strategies in watershed management.
• Illustrated the utility of a hybrid modeling framework for hydrological effect attribution analysis with high spatial resolution in data-scarce regions.

Funding

• Shanxi Provincial Philosophy and Social Sciences Research Project (Grant No. 2025QN181)
• Program for Guangdong Introducing Innovative and Entrepreneurial Teams (2021ZT090543)

Citation

@article{Liang2026Interactive,
  author = {Liang, Yanan and Cai, Yanpeng and Niu, Junjie and Wang, Xuan},
  title = {Interactive driven force analysis of blue and green water for Yalong River Basin of southwest China based on a hybrid modeling approach},
  journal = {Journal of Hydrology Regional Studies},
  year = {2026},
  doi = {10.1016/j.ejrh.2026.103133},
  url = {https://doi.org/10.1016/j.ejrh.2026.103133}
}