Zhang et al. (2026) A many-objective simulation-optimization framework for integrated water resources management in canal-well combined irrigation area based on FloPy and NSGA-III

Identification

• Journal: Ecological Indicators
• Year: 2026
• Date: 2026-01-01
• Authors: Yao Zhang, Yanan Jiang, Qihao Ma, Ya Yan, Jianzhe Hou, Xun Zhang, Jianqiang He, Xiaojun Wang, Qiang Li, Shikun Sun
• DOI: 10.1016/j.ecolind.2025.114581

Research Groups

• College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling, Shaanxi Province, PR China
• Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, Yangling, Shaanxi Province, PR China
• State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan, Hubei Province, PR China
• National Key Laboratory of Water Disaster Prevention, Nanjing Hydraulic Research Institute, Nanjing, Jiangsu Province, PR China
• Research Center for Climate Change, Ministry of Water Resources, Nanjing, PR China
• College of Forestry, Northwest A&F University, Yangling, Shaanxi Province, PR China
• Qinling National Forest Ecosystem Research Station, Yangling, Shaanxi, PR China
• Xinjiang Research Institute of Agriculture in Arid Areas, Urumqi, Xinjiang, China

Short Summary

This study developed a tightly coupled simulation-optimization framework using FloPy and NSGA-III to manage integrated water resources in canal-well combined irrigation areas. The framework successfully determined optimal canal-well irrigation volumes and proportions, balancing multiple objectives and mitigating groundwater level fluctuations across different hydrological years.

Objective

• To develop a simulation-optimization framework for conjunctive management of surface water and groundwater, explicitly incorporating spatial heterogeneity and interannual hydrological variability.
• To explore the Pareto Front among five conflicting objectives: maximizing water productivity, maximizing total income, minimizing irrigation water loss, minimizing the Gini coefficient (equity), and minimizing groundwater level annual fluctuations.
• To screen out the optimal water resource allocation scheme under wet, normal, and dry hydrological years.

Study Configuration

• Spatial Scale: Jinghuiqu irrigation area, Shaanxi Province, China, covering 1180 km² across six administrative districts.
• Temporal Scale: Groundwater model calibration from January 1, 2007, to December 26, 2009; validation from January 1, 2010, to December 26, 2013. Optimization performed for typical wet, normal, and dry years.

Methodology and Data

• Models used:
  • MODFLOW (three-dimensional groundwater flow simulation program)
  • FloPy (Python package for MODFLOW model development, running, and post-processing)
  • Pymoo (multi-objective optimization framework)
  • NSGA-III (many-objective genetic algorithm)
  • PEST (for groundwater model calibration)
  • Entropy-TOPSIS (for multi-criteria decision-making and scheme selection)
  • Augmented Scalarization Function (ASF)
• Data sources:
  • Observed groundwater levels from eight observation wells (recorded at 5-day intervals).
  • Hydrogeological conditions of the study area.
  • Rainfall infiltration, canal leakage, field irrigation infiltration, and well irrigation return flow data.
  • Crop planting structures and crop water requirements (calculated using the Penman-Monteith equation).
  • Land use reclassification map and Digital Elevation Model (DEM) of the Jinghuiqu irrigation area.

Main Results

• The proposed simulation-optimization framework effectively determined reasonable canal-well combined irrigation water volumes and proportions for sustainable management.
• Recommended schemes resulted in average groundwater level fluctuations of +0.82 m in wet years, +0.063 m in normal years, and -0.26 m in dry years, demonstrating effective regulation.
• Optimal canal-to-well irrigation ratios for recommended schemes were 1:2.25 (wet year), 1:1.19 (normal year), and 1:1.74 (dry year), highlighting the importance of adaptive management.
• The framework successfully balanced five objectives: water productivity (e.g., 3.34-4.77 kg/m³), total income (e.g., 136.28-166.63 ×10⁸ ¥), irrigation water loss (e.g., 0.46-2.45 ×10⁷ m³), equity (Gini coefficient, e.g., 0.01-0.42), and groundwater level annual fluctuation (e.g., 0.14-1.75 m).
• The tightly coupled model revealed distinct spatial-temporal variations in water allocation across administrative districts, emphasizing its potential for integrated surface water and groundwater management.
• Groundwater levels in recommended schemes showed a slow rising trend in wet years, slight decrease and recovery in normal years, and controlled decrease and recovery in dry years, avoiding significant depression cones.

Contributions

• Developed a novel, tightly coupled simulation-optimization framework integrating FloPy (for groundwater simulation) and NSGA-III (for many-objective optimization) for integrated water resources management.
• Explicitly incorporated spatial heterogeneity (administrative districts, crop structures) and interannual hydrological variability, addressing limitations of previous simplified models.
• Provided a comprehensive approach to balance five conflicting objectives (water productivity, total income, water loss, equity, groundwater level fluctuation) in canal-well combined irrigation areas.
• Demonstrated the ability to determine appropriate water quantities and ratios of canal and well irrigation for different districts and hydrological years.
• Achieved the regulatory goal of mitigating annual groundwater level fluctuations and promoting "increasing groundwater storage in wet year and utilizing it fully in dry year" within a reasonable range.

Funding

• Open fund for State Key Laboratory of Water Resources Engineering and Management (Wuhan University, 2024SWG03)
• Key Research and Development Program of Shaanxi (2024SF-YBXM-533)
• Shaanxi Province Water Conservancy Science and Technology Project (Grant No. 2024slkj-10)
• Special project of scientific and technological innovation of Xinjiang Research Institute of Arid Area Agriculture (XJHQNY-2025-8)
• Research Project of Shaanxi Laboratory for Arid Region Agriculture (2024ZY-JCYJ-02-40)
• National Natural Science Foundation of China (No. 52579045, 52121006, 41961124006)
• National Key Research and Development Program of China (2016YFC0400305, 2022YFF1302200)
• Young Top-Notch Talent Support Program of National High-level Talents Special Support Plan
• Research Project of Ministry of Natural Resources (No. 20210103)

Citation

@article{Zhang2026manyobjective,
  author = {Zhang, Yao and Jiang, Yanan and Ma, Qihao and Yan, Ya and Hou, Jianzhe and Zhang, Xun and He, Jianqiang and Wang, Xiaojun and Li, Qiang and Sun, Shikun},
  title = {A many-objective simulation-optimization framework for integrated water resources management in canal-well combined irrigation area based on FloPy and NSGA-III},
  journal = {Ecological Indicators},
  year = {2026},
  doi = {10.1016/j.ecolind.2025.114581},
  url = {https://doi.org/10.1016/j.ecolind.2025.114581}
}