Zongjie et al. (2025) Increased rainfall alters soil moisture dynamics in alpine meadows

Identification

• Journal: Journal of Hydrology
• Year: 2025
• Date: 2025-11-28
• Authors: Li Zongjie, Hao Li, Bowen Wang, Juan Gui, Xiaoying Liu, Fang Liu
• DOI: 10.1016/j.jhydrol.2025.134681

Research Groups

• School of Civil and Hydraulic Engineering, Lanzhou University of Technology, Lanzhou 730050, China
• Observation and Research Station of Eco-Hydrology and National Park by Stable Isotope Tracing in Qilian Mountains/National Key Laboratory of Ecological Security and Sustainable Development in Arid Region, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China

Short Summary

This study investigated the impact of increased precipitation on soil moisture dynamics and water sources in alpine meadows on the Qinghai-Tibet Plateau, revealing that enhanced rainfall significantly reorders the vertical sequence and timing of soil water sources, shifting recharge towards supra-permafrost water.

Objective

• To quantify soil-water sources and dynamics and assess management implications under increased precipitation in alpine meadows, focusing on the effects of a +30 % precipitation increase compared to natural conditions.

Study Configuration

• Spatial Scale: 30 experimental plots, each 3 meters by 3 meters, located in alpine meadows on the Qinghai-Tibet Plateau.
• Temporal Scale: Seasonal observations from June to October, capturing variations in soil water dynamics and isotopic signatures.

Methodology and Data

• Models used: Line–conditioned excess (lc–excess) and end–member mixing analysis (EMMA).
• Data sources: Data collected from a randomized-block, full-factorial rainfall-by-temperature experiment manipulating rainfall (−30 %, 0, +30 %) and temperature. Soil water content and stable isotopes (δ18O, δ2H, d-excess) were measured.

Main Results

• Under increased precipitation (+30 %), surface (0–10 cm) soil water content was significantly higher than in natural control plots, with smaller differences observed at 10–20 cm depth.
• The soil water line slope was shallow in June but markedly increased from July to August.
• lc-excess mass balance indicated piston flow from June to July and in October, while preferential flow dominated between August and September.
• Rapid infiltration under increased precipitation diluted isotopic signatures at depth.
• Precipitation and soil temperature were the primary drivers of isotope dynamics; increased precipitation led to more negative δ18O and δ2H values and increased d-excess, whereas warming intensified shallow evaporation, enriching δ18O and δ2H and lowering d-excess.
• Deep-soil isotopes remained comparatively stable.
• Enhanced precipitation shifted the recharge toward supra-permafrost water, delaying contributions from ground-ice meltwater, in contrast to natural conditions where recharge was dominated by deep groundwater.

Contributions

• Demonstrated that increased precipitation significantly reorders the vertical sequence and timing of soil–water sources in permafrost regions.
• Provided scientific support for restoration measures and criteria tailored for wetter conditions in alpine meadows.
• Proposed a three–stage strategy (involving +30 %, 0 %, and −30 % rainfall scenarios) to enhance multi–tier soil–water–ecosystem resilience and guide hydro–ecological management and ecological restoration in cold regions like the Qinghai–Tibet Plateau under climate-induced precipitation changes.

Funding

Not specified in the provided text.

Citation

@article{Zongjie2025Increased,
  author = {Zongjie, Li and Li, Hao and Wang, Bowen and Gui, Juan and Liu, Xiaoying and Liu, Fang},
  title = {Increased rainfall alters soil moisture dynamics in alpine meadows},
  journal = {Journal of Hydrology},
  year = {2025},
  doi = {10.1016/j.jhydrol.2025.134681},
  url = {https://doi.org/10.1016/j.jhydrol.2025.134681}
}