Su et al. (2026) Evapotranspiration intensification will drive terrestrial water storage decline in the Turpan–Hami Basin

Identification

• Journal: Journal of Hydrology
• Year: 2026
• Date: 2026-10-01
• Authors: Yanxin Su, Guojing Gan, Jingyi Bu, GAO Yanchun
• DOI: 10.1016/j.jhydrol.2026.136508

Research Groups

• Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
• University of the Chinese Academy of Sciences, Beijing, China
• Key Laboratory of Lake and Watershed Science for Water Security, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, China
• Earth Systems Research Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH, USA

Short Summary

This study developed a bias-corrected, fully coupled CWatM–MODFLOW model for the hyper-arid Turpan–Hami Basin using a novel multi-objective calibration scheme. It projects that warming-driven evapotranspiration intensification will lead to significant terrestrial water storage decline in the 21st century, despite modest precipitation gains.

Objective

• To develop a bias-corrected, fully coupled surface–subsurface hydrological model (CWatM–MODFLOW) for the Turpan–Hami Basin using a novel multi-objective calibration scheme to improve the simulation of regional water storage dynamics and flux partitioning.
• To conduct an integrated assessment of 21st-century terrestrial water storage anomaly (TWSA) evolution under Shared Socioeconomic Pathway (SSP) scenarios, including sensitivities, contributions of precipitation and evapotranspiration, lagged responses, and compound extremes.

Study Configuration

• Spatial Scale: Turpan–Hami Basin (THB), northwestern China.
• Temporal Scale:
  • Calibration: 2003–2013
  • Validation: 2014–2019
  • Future Projection: 21st century (specifically 2041–2100 for compound extremes)

Methodology and Data

• Models used:
  • CWatM–MODFLOW (fully coupled surface–subsurface hydrological model)
  • Potential Evapotranspiration (PET) schemes: Penman-Monteith (PM), Priestley-Taylor (PT), and PT with α-tuning plus systematic bias correction.
• Data sources:
  • Terrestrial Water Storage Anomalies (TWSA): GRACE/GRACE–FO observations.
  • Evapotranspiration (ET): PML–V2 product.
  • Climate forcing data: ISIMIP3b dataset, bias–adjusted to ERA5.
  • Future climate scenarios: Shared Socioeconomic Pathways (SSP1-2.6, SSP3-7.0, SSP5-8.5).

Main Results

• The novel multi-objective calibration scheme, incorporating GRACE/GRACE-FO TWSA and PML-V2 ET, significantly improved ET simulation skill (KGE = 0.858, NSE = 0.707, PBIAS = 2.3%) and maintained robust TWSA performance (KGE = 0.783) during calibration (2003–2013), outperforming default PET schemes.
• The improved ET scheme demonstrated strong accuracy (KGE = 0.828, NSE = 0.690, PBIAS = −3.1%) and good cross-period generalization during validation (2014–2019).
• Future climate projections indicate accelerated warming, with minimum temperatures rising faster than maximum temperatures, leading to a narrowing diurnal temperature range, alongside moderate increases in precipitation.
• Projected TWSA reveals scenario-dependent declines, with the strongest and fastest acceleration under SSP5-8.5, followed by SSP3-7.0.
• Attribution analysis shows that annual TWSA responses to precipitation (positive) and ET (negative) are approximately symmetric and opposite in sign, with ET intensification dominating storage decline under stronger climate forcing. Monthly diagnostics indicate a negative lag from ET to TWSA.
• The co-occurrence of low TWSA and elevated ET is projected to become more pronounced over 2041–2100, with the strongest signal under SSP5-8.5.
• Overall, the Turpan–Hami Basin exhibits an energy–water coupling where warming-driven ET intensification largely offsets modest precipitation gains, leading to lagged terrestrial water storage deficits.

Contributions

• Developed and applied a bias-corrected, fully coupled CWatM–MODFLOW model for the hyper-arid Turpan–Hami Basin, addressing the scarcity of such integrated modeling studies in the region.
• Introduced a novel multi-objective calibration scheme that jointly assimilates GRACE/GRACE–FO terrestrial water storage anomalies and PML–V2 evapotranspiration product, significantly improving model robustness and physical consistency.
• Benchmarked and improved potential evapotranspiration (PET) schemes for extreme arid conditions, demonstrating the superior performance of a PT-α and bias-corrected scheme.
• Provided an integrated assessment of future terrestrial water storage evolution in a hyper-arid basin under climate change scenarios, quantifying the dominant role of evapotranspiration intensification over precipitation gains.
• Highlighted the energy–water coupling and the mechanism of lagged storage deficits due to vadose-zone and shallow-aquifer moisture memory in hyper-arid environments.

Funding

Not explicitly mentioned in the provided text.

Citation

@article{Su2026Evapotranspiration,
  author = {Su, Yanxin and Gan, Guojing and Bu, Jingyi and Yanchun, GAO},
  title = {Evapotranspiration intensification will drive terrestrial water storage decline in the Turpan–Hami Basin},
  journal = {Journal of Hydrology},
  year = {2026},
  doi = {10.1016/j.jhydrol.2026.136508},
  url = {https://doi.org/10.1016/j.jhydrol.2026.136508}
}