Gangi et al. (2026) Impact of strip subdivision on water conservation in border irrigation for irregularly shaped fields

Identification

• Journal: Agricultural Water Management
• Year: 2026
• Date: 2026-01-06
• Authors: Fabiola Gangi, Carmelina Costanzo, Margherita Lombardo, Pierfranco Costabile, Cosimo Peruzzi, Claudio Gandolfi, Daniele Masseroni
• DOI: 10.1016/j.agwat.2025.110101

Research Groups

• Department of Agricultural and Environmental Sciences, University of Milan, Italy
• Department of Environmental Engineering, University of Calabria, Italy
• Italian Institute for Environmental Protection and Research (ISPRA), Area for Hydrology, Hydrodynamics, Hydromorphology and Freshwater Ecology (BIO–ACAS), Italy

Short Summary

This study investigated the water-saving potential of geometric reconfiguration in a 1.9-hectare irregularly shaped field in the Padana Plain, Italy, traditionally irrigated by border irrigation. It found that strip subdivision alone reduced water use by 34%, with model-based optimization suggesting total savings of up to 42% without compromising crop yield.

Objective

• To investigate the impact on water savings achieved through the implementation of optimized land preparations on an irregularly bordered irrigated field in the Padana Plain, Italy.
• To quantify the extent to which optimized field geometry alone could reduce water consumption during irrigation events without compromising crop yield.

Study Configuration

• Spatial Scale: A 1.9-hectare (19,000 m²) irregularly shaped, closed-end border-irrigated field in the Lombardy region of Northern Italy (45.30 N, 10.69 E), cultivated with maize.
• Temporal Scale: Two consecutive irrigation seasons were monitored (2023 and 2024), with agro-meteorological data collected from April to September in both years.

Methodology and Data

• Models used: IrriSurf2D, a two-dimensional hydrodynamic model that integrates shallow water equations with the Green-Ampt approach for infiltration.
• Data sources:
  • High-resolution topographic data (Digital Elevation Model - DEM) with a ground resolution of approximately 3 cm and a horizontal/vertical accuracy of ±1.5 cm, obtained from ad-hoc topographic surveys in 2023 and 2024.
  • Applied inflow rates measured with a SonTek-IQ area velocity flow meter.
  • Irrigation intervention times counted with a chronometer.
  • Water advance detected by nine EGK-LW20L00 multi-purpose water level sensors.
  • Agro-meteorological variables (rainfall, global radiation, air temperature, relative humidity, wind speed, and reference crop evapotranspiration) monitored by an ATMOS 41 weather station.
  • Farmer's experience and qualitative sketches of irrigated areas.
  • Best practices from surface irrigation handbooks and manuals.

Main Results

• Field implementation of strip subdivision reduced the average irrigation volume per unit area by 34%, from approximately 2600 m³/ha in 2023 to 1700 m³/ha in 2024.
• Model-based optimization of irrigation durations suggested an additional 10% water saving, potentially reducing the average water use to 1500 m³/ha, leading to a total reduction of about 42% compared to 2023 practices.
• Crop yield remained stable at approximately 55 tonnes/ha of silage maize in both 2023 and 2024, indicating no negative impact from reduced water application.
• Strip subdivision significantly improved irrigation uniformity, reducing dry areas from approximately 38% of the total field area in 2023 to about 18% in 2024.
• The IrriSurf2D model accurately replicated surface irrigation dynamics, with Root Mean Square Error (RMSE) of approximately 5 minutes for waterfront advance time and 10 mm for maximum water depth.
• The cost and time for implementing strip subdivision (dike construction with a tractor-drawn device) were negligible, taking about 20 minutes (approximately 10 min/ha).

Contributions

• Quantified the significant water-saving potential (34-42%) of geometric reconfiguration (strip subdivision) in an irregularly shaped, closed-end border-irrigated field without compromising crop yield.
• Demonstrated the effectiveness of precision surface irrigation principles, specifically land preparation and irrigation timing optimization, even in complex field geometries.
• Highlighted the necessity and benefits of using 2D hydrodynamic models (like IrriSurf2D) over 1D approaches for accurately simulating and optimizing irrigation performance in fields with irregular shapes, multiple inlets, and micro-topographic variations.
• Provided evidence that low-cost and easily implementable interventions can substantially enhance water use efficiency in traditional gravity-fed irrigation systems, offering a sustainable alternative to the systematic transition to pressurized systems.

Funding

• IrriGate project "Toward a smart and flexible irrigation management in gravity-fed irrigation contexts"
• IrriSuS project "Sustanible Surface Irrigation" (Regione Lombardia, PSR 1.2.01; year 2019 - Grant no. 201901319885)
• IrriSuP "Precision Surface Irrigation" (Regione Lombardia, PSR 1.2.01; year 2022 - Grant n. 202202220204 - year 2025 Grant n. 202503112318)
• Agritech National Research Center (European Union Next-GenerationEU, PIANO NAZIONALE DI RIPRESA E RESILIENZA (PNRR) - MISSIONE 4 COMPONENTE 2, INVESTIMENTO 1.4 - D.D. 1032 17/06/2022, CN00000022)
• IDRATARE project (Premio Florisa Melone 2024, Società Idrologica Italiana (SII))

Citation

@article{Gangi2026Impact,
  author = {Gangi, Fabiola and Costanzo, Carmelina and Lombardo, Margherita and Costabile, Pierfranco and Peruzzi, Cosimo and Gandolfi, Claudio and Masseroni, Daniele},
  title = {Impact of strip subdivision on water conservation in border irrigation for irregularly shaped fields},
  journal = {Agricultural Water Management},
  year = {2026},
  doi = {10.1016/j.agwat.2025.110101},
  url = {https://doi.org/10.1016/j.agwat.2025.110101}
}