Han et al. (2025) Regional dynamics in the irrigation requirement of maize and wheat crops in relation to changes in the climate and cultivated area in the Shandong’s Yellow River Basin

Identification

• Journal: Agricultural Water Management
• Year: 2025
• Date: 2025-11-24
• Authors: Xin Han, Zhanhong Ma, Baozhong Zhang, Zhigong Peng, Kai Zhang, Xin Li
• DOI: 10.1016/j.agwat.2025.109979

Research Groups

• College of Water Conservancy Engineering, Tianjin Agricultural University, Tianjin 300392, China
• State Key Laboratory of Water Cycle and Water Security, China Institute of Water Resources and Hydropower Research, Beijing 100038, China
• Tianjin Agricultural University-China Agricultural University Joint Smart Water Conservancy Research Center, Tianjin 300392, China

Short Summary

This study analyzed the spatiotemporal variations and driving factors of irrigation water requirement (IWR) for maize and wheat in Shandong’s Yellow River Basin from 2003 to 2023. It revealed that a "warm-dry" climate trend combined with cultivated area expansion significantly increased IWR, with cultivated area being the dominant driver.

Objective

• To systematically uncover the spatiotemporal evolution patterns of climate variables, wheat and maize planting areas, and irrigation water requirement (IWR) from 2003 to 2023 in the Yellow River irrigation areas of Shandong Province.
• To quantify the relative contributions of meteorological factors and cultivated area to changes in IWR and to project future trends.

Study Configuration

• Spatial Scale: Yellow River irrigation areas in Shandong Province, North China Plain (34°33′–38°16′N, 114°48′–119°19′E), covering 53 administrative units (county-level cities and municipal districts) across 9 cities.
• Temporal Scale: 21 years, from 2003 to 2023.

Methodology and Data

• Models used:
  • Theil–Sen (T–S) estimator for trend analysis.
  • Mann–Kendall (M–K) test for trend significance and mutation points.
  • Hurst exponent (Rescaled Range method) for assessing trend persistence.
  • Penman–Monteith equation (FAO-56) for potential evapotranspiration (ETo) calculation.
  • Crop coefficient (Kc) method (FAO-56 adjusted with local meteorological data) for crop evapotranspiration (ETc).
  • US Department of Agriculture Soil Conservation Service method for effective precipitation (Pe).
  • Sensitivity analysis method to quantify the influence of factors on IWR.
  • Contribution analysis method to quantify each factor’s contribution to IWR variations.
  • Kriging interpolation method for spatial characteristics.
• Data sources:
  • Daily meteorological data (maximum, minimum, and average temperature, wind speed, relative humidity, sunshine duration, precipitation) from 2003 to 2023 for 53 administrative units, obtained from the National Meteorological Information Center (http://data.cma.cn).
  • Annual wheat and maize sown area data from 2003 to 2023 for 53 administrative units, obtained from municipal-level Statistical Yearbooks.

Main Results

• The study area experienced a significant "warm-dry" trend from 2003 to 2023, characterized by increases in temperature (T), sunshine duration (SD), and potential evapotranspiration (ETo), and overall declines in relative humidity (RH) and wind speed (Ws).
• Temperature increased significantly across most regions (Tmax: 98.1%, Tmean: 92.5%, Tmin: 73.6% of regions), with warming rates of 0.08 °C per year, 0.07 °C per year, and 0.06 °C per year, respectively.
• Cultivated area for wheat and maize expanded by an average of 3.3% per year. Wheat sown area increased by 62.8% from 2003 to 2023, and maize sown area increased from 1.00 Mha to 2.18 Mha.
• The irrigation water requirement (IWR) showed a significant increasing trend in 88.7% of the region, rising by 48.23 m³ per hectare per year, with a distinct north–south spatial differentiation. The annual cumulative IWR ranged from 65.15 × 10⁸ m³ to 164.88 × 10⁸ m³.
• Cultivated area was identified as the dominant driver of IWR increase, contributing 0.61 × 10⁸ m³.
• Declining RH and rising T were the primary climatic contributors to increased IWR, with respective contributions of 0.15 × 10⁸ m³ and 0.13 × 10⁸ m³.
• Spatially, RH was the most sensitive factor (sensitivity coefficient = -0.78), notably exceeding planted area (0.63) and temperature (0.45). The southwestern region was most sensitive to RH and T changes, while parts of the north responded strongly to shifts in planted area.
• Trend projections using the Hurst exponent indicate that the total IWR is expected to rise by 22.7%, from 176.27 × 10⁸ m³ in 2023 to 216.22 × 10⁸ m³ in 2033.

Contributions

• Integrates climate and non-climate factors (policy-driven adjustments in crop area) into a unified framework for coupled analysis of IWR changes, addressing a limitation of previous studies that often focused on single drivers or treated cropping structure as static.
• Provides a systematic and comprehensive long-term analysis (2003-2023) of climate change, wheat–maize planting structure evolution, and their relationship with spatiotemporal IWR dynamics in the strategically important Yellow River irrigation areas of Shandong Province.
• Quantifies the relative contributions of climate change and human activities (cultivated area expansion) to IWR changes using a robust methodology (sensitivity and contribution analysis based on partial derivatives), offering a more realistic understanding of integrated driving mechanisms.
• Employs the Hurst exponent to assess the persistence of historical trends, providing projections for future IWR and informing differentiated water conservation and climate adaptation strategies.
• Considers staple crops (wheat and maize) in the study area, breaking through the limitations of single-crop studies and aligning with regional agricultural reality.

Funding

• Key Research & Development Program of Shandong Province (No. 2024CXGC010912)
• National Natural Science Foundation of China (No. 52130906)
• Fund of China Institute of Water Resources and Hydropower Research (No. ID0145B022021)
• Open Research Fund of Yinshanbeilu Grassland Eco-hydrology National Observation and Research Station, China Institute of Water Resources and Hydropower Research (No. YSS202503)

Citation

@article{Han2025Regional,
  author = {Han, Xin and Ma, Zhanhong and Zhang, Baozhong and Peng, Zhigong and Zhang, Kai and Li, Xin},
  title = {Regional dynamics in the irrigation requirement of maize and wheat crops in relation to changes in the climate and cultivated area in the Shandong’s Yellow River Basin},
  journal = {Agricultural Water Management},
  year = {2025},
  doi = {10.1016/j.agwat.2025.109979},
  url = {https://doi.org/10.1016/j.agwat.2025.109979}
}