Abstract
The Yalong and Dadu River basins (Yangtze headwaters) serve as critical “water towers” for ecosystems and strategic diversions. However, climate warming may decouple atmospheric inputs from hydrological responses, exposing the limitations of traditional runoff-centric assessments that overlook terrestrial water storage dynamics. To address this gap, this study develops a probability-based diagnostic framework integrating the SWAT model with a novel Water Balance Resilience Index (WBRI) to evaluate basin health evolution (1961–2018). Annual water storage change was quantified via the hydrological water balance, standardized into a Normalized Storage Index (NSI), and transformed into the WBRI by fitting probability distributions to absolute anomaly magnitudes and mapping them to hydrological return periods on a continuous 0–1 health scale. Results reveal a significant non-linear divergence: while precipitation and evapotranspiration in the Dadu basin declined markedly, runoff remained relatively stable. This stability may be associated with cryospheric and storage-related buffering, which partly compensates for precipitation deficits through enhanced cryospheric contributions and reduced evapotranspiration under water-limited conditions. Phase-space diagnosis identified a recurring flux–state decoupling pattern, with the “High Flux–Low State” anomaly occurring at comparable frequencies in the Source Region and Sink group (both 19.8%) and varying across subbasins from 13.8% to 22.4%. This suggests that stable discharge may exert a “masking effect,” concealing potential depletion of terrestrial water storage and legacy cryospheric reserves. Furthermore, the WBRI indicates that since 2010, both basins have tended toward a more vulnerable or tighter water-balance state, with reduced resilience to hydro-climatic variability. These findings support a flux–state collaborative monitoring framework. For the West Route Diversion Project, a hierarchical “Mainstem Control + Tributary Quotas” mode is suggested, in which transferable water limits consider storage-state indicators rather than runoff abundance alone. This may help reduce long-term storage-depletion risk and support alpine ecosystem sustainability.
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Acknowledgements
The Evaporation dataset of the Tibetan Plateau at the monthly scale (1979-2018) V2.0 used in this study was provided by the National Tibetan Plateau Data Center (http://data.tpdc.ac.cn).The authors are grateful to anonymous reviewers for their detailed comments, which have significantly improved the presentation of this work, Readers can also contact the first author via< [email protected]> for questions about the paper.
Funding
This research was funded by [the National Key Research and Development Program of China] grant number [2022YFC3202401]. [Graduate Dissertation Fund of Nanjing Hydraulic Research Institute] grant number [Yy524013].
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The SRTM DEM data is accessible from the Geospatial Data Cloud site. The specific processing and stitching for the China region was described by the data provider (http://www.gisrs.cn/?data_163/0ad6a9fa-b32b-4d91-8589-43fbf3859272.html ).
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The China Multi-period Land Use Remote Sensing Monitoring Dataset (CNLUCC) was provided by the Resource and Environment Science and Data Center, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences (https://www.resdc.cn/DOI/DOI.aspx?DOIID=54).
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Yang, J., Yan, B., Li, E. et al. Flux-state decoupling reveals water-balance resilience in Tibetan headwaters.
Sci Rep (2026). https://doi.org/10.1038/s41598-026-61179-1
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DOI: https://doi.org/10.1038/s41598-026-61179-1
Keywords
- Yangtze headwaters
- Water balance resilience index (WBRI)
- Flux-state mismatch
- Cryospheric buffering
- SWAT model
- Adaptive water management
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