Yang et al. (2025) Effects of extreme climate on hydrological dynamics in dryland apple orchards: a modeling study

Identification

• Journal: Agricultural Water Management
• Year: 2025
• Date: 2025-12-12
• Authors: Yumeng Yang, Qi Liu, Xiaodong Gao, Xiaoya Shao, Min Yang
• DOI: 10.1016/j.agwat.2025.110074

Research Groups

• College of Soil and Water Conservation Science and Engineering, Northwest A&F University, China.
• Institute of Soil and Water Conservation, Chinese Academy of Science & Ministry of Water Resources, China.
• University of Chinese Academy of Sciences, China.
• College of Natural Resources and Environment, Northwest A&F University, China.

Short Summary

This study integrates a dynamic leaf area index (LAI) sub-module into the process-oriented STEMMUS model to accurately simulate the ecohydrological responses of dryland apple orchards to climate extremes. The findings demonstrate that while increased precipitation volume enhances soil water storage, both 2°C warming and high-intensity precipitation patterns significantly reduce canopy transpiration and water use efficiency (T/ET).

Objective

• To develop and validate a dynamic LAI development sub-module for the STEMMUS model to improve simulations of phenology-driven vegetation responses.
• To systematically quantify the effects of precipitation amount, precipitation intensity, and atmospheric temperature on vertical soil moisture, evapotranspiration (ET) partitioning, and soil water storage (SWS).

Study Configuration

• Spatial Scale: Field-scale experimental plots (Zizhou County, Shaanxi Province, China) on the Loess Plateau, with vertical soil profile analysis extending to a depth of 4.5 m.
• Temporal Scale: Growing seasons (April–October) for calibration (2019) and validation (2020), supplemented by a 30-year historical simulation (1991–2020) for scenario analysis.

Methodology and Data

• Models used: STEMMUS (Simultaneous Transfer of Energy, Mass, and Momentum in Unsaturated Soil) coupled with a dynamic LAI development sub-module based on the SWAT 2012/EPIC phenological framework.
• Data sources: In-situ field observations (soil moisture and temperature sensors at 0.2, 0.6, 2.0, 3.0, and 4.5 m; sap flow meters; LAI-2200C canopy analyzer; fine root sampling) and meteorological data from an automatic weather station and the Suide Meteorological Station.

Main Results

• Model Enhancement: The coupled model significantly improved transpiration simulation accuracy, reducing the Normalized Root Mean Square Error (NRMSE) from 40.2–61.9% (original model) to 30.0–33.2%.
• Soil Water Storage (SWS): Increased precipitation (1.5× ambient) enhanced SWS in shallow (0–200 cm) and deep (200–450 cm) layers by 71.9 mm and 124.9 mm, respectively. A 2°C warming scenario resulted in maximum SWS reductions of 30.6 mm (shallow) and 29.7 mm (deep).
• Precipitation Intensity: High-intensity rainfall (merging events) showed limited capacity for deep soil recharge and reduced cumulative canopy transpiration by 9.7–16.4%.
• Evapotranspiration Partitioning: Cumulative canopy transpiration (T) and the T/ET ratio increased with precipitation amount. However, 2°C warming and high-intensity precipitation decreased T/ET by 8.9–15.5% and 4.0–9.4%, respectively.
• Soil Evaporation: Warming (2°C) markedly increased cumulative soil evaporation by 11.5–15.7%, whereas precipitation intensity had no significant impact on evaporation.

Contributions

• Model Innovation: Addressed a structural limitation in the STEMMUS model by replacing static LAI inputs with a dynamic, phenology-driven growth module, enhancing its reliability for long-term hydrological simulations.
• Ecohydrological Insights: Quantified the sensitivity of deep soil water to climate warming and rainfall intensification, highlighting that high-intensity events do not necessarily translate to deep-layer replenishment in dryland orchards.
• Management Application: Provides a theoretical foundation for climate-adaptive water management, such as the necessity of supplemental irrigation or mulching to mitigate the negative impacts of warming and altered rainfall patterns on orchard sustainability.

Funding

• National Key Research and Development Program of China (2023YFD2301003).
• Shaanxi Provincial Agricultural Key Core Technology Tackling Project (2025NYGG001).

Citation

@article{Yang2025Effects,
  author = {Yang, Yumeng and Liu, Qi and Gao, Xiaodong and Shao, Xiaoya and Yang, Min and Zhao, Xining},
  title = {Effects of extreme climate on hydrological dynamics in dryland apple orchards: a modeling study},
  journal = {Agricultural Water Management},
  year = {2025},
  doi = {10.1016/j.agwat.2025.110074},
  url = {https://doi.org/10.1016/j.agwat.2025.110074}
}

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