Bellvert et al. (2024) Analysis and forecast of crop water demand in irrigation districts across the eastern part of the Ebro river basin (Catalonia, Spain): estimation of evapotranspiration through copernicus-based inputs

Identification

• Journal: Irrigation Science
• Year: 2024
• Authors: Joaquim Bellvert, Magí Pàmies-Sans, Pere Quintana Seguí, Jaume Casadesús
• DOI: 10.1007/s00271-024-00971-1

Research Groups

• Efficient Use of Water in Agriculture Program, Institute of AgriFood, Research and Technology (IRTA), Lleida, Spain
• Observatori de l’Ebre, Universitat Ramón Llull, CSIC, Roquetes, Spain

Short Summary

This study quantified and analyzed the actual and gross water demands (GWD) across eight irrigation districts (IDs) in the eastern Ebro basin (Catalonia, Spain) over six growing seasons (2017–2022) using a Copernicus-based evapotranspiration model, finding large variability in water use efficiency and projecting significant increases in water demand (up to 28% by 2100 under RCP8.5) due to climate change.

Objective

• To identify, compare, and analyze the differences between the demands, allocations, and consumptions of water for irrigation in different irrigation districts (IDs) of the eastern Ebro basin during six consecutive growing seasons (2017–2022).
• To project future crop water demands up to 2100 using global climate models under different climate scenarios (RCP4.5 and RCP8.5).

Study Configuration

• Spatial Scale: Eight Irrigation Districts (IDs) in Lleida (Catalonia, Spain), covering a total surface area of approximately 2000 square kilometers ($\text{km}^2$) within the Ebro river basin.
• Temporal Scale: Six consecutive growing seasons (15 March to 30 October) from 2017 to 2022 for historical analysis; projections extended to 2100 for climate change scenarios.

Methodology and Data

• Models used:
  • Two-Source Energy Balance Model (TSEB-PT) for estimating actual evapotranspiration ($\text{ET}_{\text{a}}$).
  • Data Mining Sharpening (DMS) approach for sharpening thermal satellite imagery (1 km to 20 m resolution).
  • FAO-56 Penman-Monteith equation for estimating reference evapotranspiration ($\text{ET}0$) and potential evapotranspiration ($\text{ET}{\text{p}}$).
  • Six CMIP5 Global Climate Models (GCMs) (MRI-CGCM3, MIROC-ESM, CNRM-CM5, MPI-ESM-MR, INMCM4, BCC-CSM1-1) for future projections.
• Data sources:
  • Satellite: Copernicus Sentinel-2 (Level-2A reflectance, 20 m resolution) and Sentinel-3 SLSTR (Level-2A Land Surface Temperature, 1 km resolution).
  • Reanalysis/Forecast: ECMWF ERA5 reanalysis (meteorological inputs) and Copernicus Atmosphere Monitoring Service (CAMS) forecast dataset (Aerosol Optical Thickness).
  • Ancillary/Ground Data: DUN-SIGPAC database (crop classification), Copernicus Climate Change Service (C3S) land cover maps, SRTM DEM, and 49 public agrometeorological stations (precipitation data interpolated using IDW).

Main Results

• Historical Water Demand (2017–2022): The average total Gross Water Demand (GWD) for all IDs was $1036 \pm 142$ cubic hectometers ($\text{hm}^3$) per season, representing about 30% of the natural river regime contributions.
• Evapotranspiration Variability: Cumulative $\text{ET}{\text{a}}$ showed significant variations between IDs and years, averaging 788 mm per season. IDs with the highest water allocations (AB, CAYC, CU) showed the highest $\text{ET}{\text{a}}$ rates.
• Crop Water Consumption: Forages, summer crops, double cropping, and oilseeds had the highest cumulative $\text{ET}_{\text{a}}$ (ranging from 822 to 891 mm/season), while grapevines, olive, and nut trees had the lowest (682 to 742 mm/season).
• Efficiency and Allocation Mismatch: The Canal d’Urgell (CU), predominantly using flood irrigation (84% of fields), accounted for about 50% of the total GWD ($520 \pm 52 \text{hm}^3$), indicating very low water use efficiency. Some IDs (GS, SS) exceeded their limited theoretical water allocations, suggesting widespread sustained deficit irrigation.
• 2022 Drought Impact: During the extreme drought year of 2022, $\text{ET}{\text{a}}$ was 8% higher and GWD was 14% higher (an increase of $568 \text{m}^3/\text{ha}$) compared to the 2017–2021 average, driven by higher $\text{ET}0$ (6% higher) and lower precipitation (30% lower).
• Future Projections (up to 2100): All climate projections show an upward trend in potential evapotranspiration ($\text{ET}{\text{p}}$).
  • By 2050, $\text{ET}0$ is projected to increase by 6% (RCP4.5) to 11% (RCP8.5).
  • By 2100, $\text{ET}0$ is projected to increase by 12% (RCP4.5, 1100 mm) to 28% (RCP8.5, 1260 mm).
  • Total $\text{ET}{\text{p}}$ for the region is expected to increase by $150 \text{hm}^3$ (RCP4.5) to $350 \text{hm}^3$ (RCP8.5) by 2100.

Contributions

• Operational application of the high-resolution SEN-ET modeling framework (TSEB-PT with Copernicus inputs) to quantify actual evapotranspiration and water demands across multiple, diverse irrigation districts over a six-year period.
• Detailed comparative analysis of water demands, allocations, and irrigation system efficiencies at the ID level, providing actionable insights for water managers regarding resource distribution and modernization needs (e.g., highlighting the inefficiency of CU).
• Quantification of the impact of the 2022 extreme drought on crop water requirements (8% increase in $\text{ET}_{\text{a}}$, 14% increase in GWD).
• Generation of long-term (up to 2100) projections of potential crop water demand under contrasting climate change scenarios (RCP4.5 and RCP8.5) for the specific IDs, aiding in future planning and mitigation policy development.

Funding

• ALTOS project (PCI2019-103649) of the PRIMA programme.
• ET4DROUGHT project (No. PID2021-127345OR-C31) of the Spanish Research Agency of the Ministry of Science and Innovation (MICINN-AEI).
• European Union’s Horizon Europe research and innovation programme under project ECO-READY (grant agreement No 101084201).
• CRUE-CSIC agreement with Springer Nature (Open Access funding).

Citation

@article{Bellvert2024Analysis,
  author = {Bellvert, Joaquim and Pàmies-Sans, Magí and Quintana‐Seguí, Pere and Casadesús, Jaume},
  title = {Analysis and forecast of crop water demand in irrigation districts across the eastern part of the Ebro river basin (Catalonia, Spain): estimation of evapotranspiration through copernicus-based inputs},
  journal = {Irrigation Science},
  year = {2024},
  doi = {10.1007/s00271-024-00971-1},
  url = {https://doi.org/10.1007/s00271-024-00971-1}
}

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