Tian et al. (2026) Freeze-thaw processes induce soil water and salt migration in farmland-ditch systems

Identification

• Journal: Journal of Hydrology
• Year: 2026
• Date: 2026-01-02
• Authors: Huiwen Tian, Yue Li, Junjie Wu, Xiayang Yu, Pei Xin
• DOI: 10.1016/j.jhydrol.2025.134897

Research Groups

• State Key Laboratory of Water Disaster Prevention, Hohai University, Nanjing, China.
• College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing, China.
• Yangtze Institute for Conservation and Development, Hohai University, Nanjing, China.

Short Summary

This study investigates the two-dimensional migration of water and salt in farmland-ditch systems during seasonal freeze-thaw cycles. It reveals that freezing induces salt recharge from ditches to farmlands, while thawing promotes drainage, characterized by a distinct temporal asymmetry in water-salt exchange.

Objective

• To examine the 2-D water-salt-heat dynamics in farmland-ditch systems under annual surface temperature fluctuations and to understand how freeze-thaw processes influence lateral water and salt exchange.

Study Configuration

• Spatial Scale: 2-D field-scale cross-section of a farmland-ditch system.
• Temporal Scale: Annual cycle encompassing seasonal freezing and thawing periods.

Methodology and Data

• Models used: A well-validated 2-D numerical model coupling water flow, salt transport, and heat transfer (including phase change).
• Data sources: The study utilizes synthetic annual surface temperature fluctuations and hydraulic parameters representative of cold-region agricultural environments to drive the numerical simulations.

Main Results

• Freezing Phase: Cryosuction creates negative pressure that drives soil water and salt to migrate laterally from the ditch into the farmland.
• Thawing Phase: Downward migration of meltwater elevates the groundwater table, reversing the hydraulic gradient and inducing drainage from the farmland back to the ditch.
• Exchange Asymmetry: The system exhibits a "gradual recharge and uneven drainage" pattern, representing a delayed response to surface temperature changes.
• Sensitivity Factors: Lower ditch water depths accelerate the lateral exchange response. Higher temperatures promote the recharge response but delay the drainage response.
• Management Optimization: Moderate ditch water depths are found to balance water supply and salt accumulation, effectively promoting salt exclusion in shallow soil layers.

Contributions

• Shifts the research focus from traditional 1-D vertical freeze-thaw dynamics to 2-D lateral interactions between ditches and farmlands.
• Identifies the asymmetrical nature of water-salt exchange driven by seasonal temperature fluctuations.
• Provides a theoretical framework for improving water and salt management strategies in cold-region irrigation and drainage systems.

Funding

• Not specified in the provided text.

Citation

@article{Tian2026Freezethaw,
  author = {Tian, Huiwen and Li, Yue and Wu, Junjie and Yu, Xiayang and Xin, Pei},
  title = {Freeze-thaw processes induce soil water and salt migration in farmland-ditch systems},
  journal = {Journal of Hydrology},
  year = {2026},
  doi = {10.1016/j.jhydrol.2025.134897},
  url = {https://doi.org/10.1016/j.jhydrol.2025.134897}
}

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