Sorando et al. (2026) Simulating mediterranean rice paddies’ water balance under climate change scenarios

Identification

• Journal: Agricultural Water Management
• Year: 2026
• Date: 2026-03-27
• Authors: Ricardo Sorando, Seonggyu Park, Jaehak Jeong, Carles Sanchis-Ibor, Francisco A. Comín
• DOI: 10.1016/j.agwat.2026.110313

Research Groups

• Departament de Geografia, Universitat de Valencia, Valencia, Spain
• Department of Civil, Environmental, & Construction Engineering (CECE) Water and the Environment Research (WATER) Center. Texas Tech University, Lubbock, TX, USA
• Texas A&M AgriLife Research, Temple, TX, USA
• Centre Valencia d’Estudis sobre el Reg (CVER), Universitat Politecnica de Valencia, Valencia, Spain
• Instituto Pirenaico de Ecología. Consejo Superior de Investigaciones Científicas (CSIC), Zaragoza, Spain
• Asociaci´on para la Integraci´on de los Servicios de los Ecosistemas (AISECO), Zaragoza, Spain

Short Summary

This study applies the SWAT+ paddy rice module to simulate the water balance of a Mediterranean rice irrigation district in Albufera de Val`encia, Spain, under climate change scenarios. Projections indicate significant precipitation reductions (9–31%) and potential evapotranspiration increases (8–18%) by mid- and late-century, leading to higher irrigation requirements (4–10%) and modest rice yield declines (up to 8%).

Objective

• Simulate paddy rice water balance under Mediterranean conditions, focusing on irrigation practices, drainage, and interactions with the wetland system using the newly developed SWAT+ paddy module.
• Reproduce the distinctive hydrology of rice paddies and its relevance for agricultural and environmental management by analyzing water balance components, with implications for irrigation optimization, environmental conservation, and climate adaptation.

Study Configuration

• Spatial Scale: Acequia del Oro irrigation community in the Albufera de Val`encia, Spain, modeled exclusively as rice paddies at high spatial resolution (5 meter Digital Elevation Model, 34 hydrological response units, 43 channels).
• Temporal Scale:
  • Calibration period: 2016–2023 (monthly irrigation volumes, daily drainage flows).
  • Climate change scenario assessment: Three 25-year blocks (Near: 2026–2050, Mid: 2051–2075, Late: 2076–2100) relative to a 1991–2017 baseline.

Methodology and Data

• Models used: SWAT+ paddy rice module. Climate models: CMIP6 Global Climate Models (GCMs) statistically downscaled by AEMET (Empirical-Statistical Downscaling and DeepESD).
• Data sources:
  • Climate inputs: Valencian Meteorology Association (AVAMET) at Tancat de la Pipa weather station (daily precipitation, air temperature, humidity, wind speed). AEMET downscaled CMIP6 products for climate change scenarios.
  • Soil properties: Detailed surveys (Moreno-Ram´on, 2013).
  • Agronomic practices: Acequia del Oro Irrigation Community, Valencian Institute for Agricultural Research (IVIA), local farmers (planting/harvest dates, irrigation schedules, fertilizer/pesticide applications, irrigation depths).
  • Observations for calibration: Monthly irrigation volumes (cubic meters) and daily drainage flows (cubic meters per second) from Acequia del Oro Irrigation Community.
  • Topography: 5 meter Digital Elevation Model (DEM).

Main Results

• Model calibration achieved high performance, with Nash–Sutcliffe Efficiency (NSE) values exceeding 0.93 and R² up to 0.94 for daily drainage flows, and NSE = 0.76 for monthly irrigation volumes.
• A Sobol-based global sensitivity analysis identified evapotranspiration (PETCO) and percolation (PERCO) as the most influential parameters governing irrigation dynamics.
• Climate change projections under SSP2-4.5 and SSP5-8.5 scenarios indicate:
  • Precipitation reductions ranging from 9% to 31% by mid- and late-century.
  • Potential evapotranspiration increases ranging from 8% to 18% by mid- and late-century.
  • Increased irrigation requirements ranging from 4% to 10% by mid- and late-century.
  • Modest rice yield declines of up to 8% by mid- and late-century.
• The Albufera paddy water balance is characterized by a managed, stepwise ponding regime where evapotranspiration is sustained across the growing season, and irrigation pulses and regulated flowout are tightly linked to ponding targets and operational drawdowns.

Contributions

• Provided a high-resolution, field-scale representation of a hydraulically regulated paddy system in very flat terrain by combining a 5 meter DEM with manual channel delineation and explicit irrigation–drainage connectivity.
• Integrated operational information from the irrigation community, including pumping-driven drainage control and recorded irrigation deliveries, to constrain the paddy water balance with observed management data.
• Implemented a transparent climate model selection approach by independently evaluating AEMET downscaled CMIP6 products (ESD and DeepESD) and constructing an ensemble from top-performing models for scenario analysis.

Funding

• Rural Development Administration, Republic of Korea (PJ015555 & PJ017314).

Citation

@article{Sorando2026Simulating,
  author = {Sorando, Ricardo and Park, Seonggyu and Jeong, Jaehak and Sanchis-Ibor, Carles and Comín, Francisco A.},
  title = {Simulating mediterranean rice paddies’ water balance under climate change scenarios},
  journal = {Agricultural Water Management},
  year = {2026},
  doi = {10.1016/j.agwat.2026.110313},
  url = {https://doi.org/10.1016/j.agwat.2026.110313}
}