Li et al. (2025) Vegetation greening decrease water yield during the growing season over the Qinling-Daba Mountains in Central China

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2025
• Date: 2025-10-15
• Authors: Zhixing Li, Xing Li, Bin Wang, Shuangshuang Li, Keqin Duan
• DOI: 10.1016/j.ejrh.2025.102852

Research Groups

• School of Geography and Tourism, Shaanxi Normal University, Xi’an, Shaanxi, China
• State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, CAS, Xi’an, Shaanxi, China

Short Summary

This study quantifies the impact of vegetation greening on water yield in the Qinling-Daba Mountains (QB) using a regional climate model with a water vapor tracer, revealing that greening significantly decreases water yield during the growing season due to a larger increase in evapotranspiration than precipitation.

Objective

• To quantify the response of water yield (precipitation minus evapotranspiration) to vegetation greening during the growing season in the Qinling-Daba Mountains (QB) and clarify whether this greening poses a burden on terrestrial water resources.

Study Configuration

• Spatial Scale: Qinling-Daba Mountains (QB) region in central China, covering approximately 300,000 km^2. The WRF model domain had a horizontal resolution of 10 km, 30 vertical layers (top at 50 hPa), and covered 300x240 grid points, encompassing most areas of China.
• Temporal Scale: Growing season (April–September) during the period 2015–2019, with simulations running from 1 March to 1 October each year (March discarded for spin-up).

Methodology and Data

• Models used:
  • WRF (Weather Research and Forecasting model, version 4.3.3)
  • WVT (Water Vapor Tracer method) embedded in WRF
  • Noah land surface model
  • Yonsei University scheme (PBL)
  • Single-Moment 6-class scheme (Microphysics)
  • Kain-Fritsch scheme (Convection)
  • RRTM scheme (Longwave radiation)
  • Dudhia scheme (Shortwave radiation)
• Data sources:
  • Initial and Boundary Conditions: NCEP FNL reanalysis data.
  • Land Cover: ESA CCI (European Space Agency Climate Change Initiative) global land cover products (300 m spatial resolution, annual interval).
  • Vegetation Variables (LAI, FVC, Albedo): GLASS (Global Land Surface Satellite) dataset (0.05° spatial resolution, 8-day temporal interval, resampled to monthly averages).
  • Evaluation Data (Precipitation, Temperature): Daily observations from 511 meteorological stations in QB and surrounding areas (National Meteorological Information Center).
  • Evaluation Data (Evapotranspiration): Average of GLEAM 4.2a (0.1° spatial resolution), MODIS MOD16A2GF Version 6.1 (500 m pixel resolution, 8-day composite), and GLASS ET product (0.05° monthly).
  • Evaluation Data (Water Yield): Derived from monthly P and ET from ERA5-Land reanalysis (0.1° horizontal resolution).

Main Results

• Vegetation greening in QB was significant, with regional average increases of 0.82 m^2 m^-2 (32.77 %) for Leaf Area Index (LAI) and 10.04 % for Vegetation Fraction (FVC). Albedo changes were negligible (0.23 %).
• Vegetation greening led to an increase in evapotranspiration (ET) by 5.12 mm month^-1 (5.03 %) and precipitation (P) by 1.20 mm month^-1 (0.76 %) during the growing season.
• The increase in ET was greater than P, resulting in a regional average decrease in water yield by 3.92 mm month^-1 (6.88 %).
• The increase in P was attributed to both enhanced local ET (Ptag, increased by 0.50 mm month^-1) and external water vapor inflow (Pad, increased by 0.70 mm month^-1).
• The relative contribution of Ptag to total P increased slightly from 7.16 % to 7.41 %, while Pad's contribution decreased from 92.84 % to 92.59 %.
• Vegetation greening altered atmospheric circulations, causing a significant reduction in water vapor inflow from the eastern and southern boundaries of QB in the lower atmospheric layer (surface to 700 hPa).
• Energetic changes included an increase in latent heat flux (5.08 W m^-2), a decrease in surface temperature (0.48 °C), an increase in atmospheric precipitable water vapor (0.04 mm), and an increase in convective available potential energy (CAPE) by 4.61 J kg^-1.
• Vegetation greening also resulted in a higher geopotential height at 700 hPa, which inhibited the inflow of external water vapor.
• Runoff in QB decreased by 3.33 mm month^-1, and soil moisture at depths of 0–10 cm, 10–40 cm, 40–100 cm, and 100–200 cm decreased by 3.07 x 10^-3 m^3 m^-3, 4.38 x 10^-3 m^3 m^-3, 5.40 x 10^-3 m^3 m^-3, and 5.15 x 10^-3 m^3 m^-3, respectively.

Contributions

• This is the first study to quantitatively assess the impact of vegetation greening on water yield in the Qinling-Daba Mountains.
• Utilized a high-resolution regional climate model (WRF) with an embedded water vapor tracer (WVT) method, allowing for the distinction and quantification of precipitation originating from local evapotranspiration versus external advection.
• Provided new insights into the underlying mechanisms by which vegetation greening affects the regional water cycle, including changes in atmospheric circulation, precipitation efficiency, and energy fluxes.

Funding

• Natural Science Fundamental Research Plan of Shaanxi Province (2023–JC–YB–251)
• Open fund of State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, CAS (SKLLQG2111)

Citation

@article{Li2025Vegetation,
  author = {Li, Zhixing and Li, Xing and Wang, Bin and Li, Shuangshuang and Duan, Keqin},
  title = {Vegetation greening decrease water yield during the growing season over the Qinling-Daba Mountains in Central China},
  journal = {Journal of Hydrology Regional Studies},
  year = {2025},
  doi = {10.1016/j.ejrh.2025.102852},
  url = {https://doi.org/10.1016/j.ejrh.2025.102852}
}