Sattar et al. (2025) A coupled land use change-ecohydrological model for multi-seasonal arid agricultural systems: an Egyptian case study

Identification

• Journal: Environmental Modelling & Software
• Year: 2025
• Date: 2025-12-26
• Authors: Aimen Sattar, Simon Moulds, Calum Brown, Mark Rounsevell, Peter Alexander
• DOI: 10.1016/j.envsoft.2025.106845

Research Groups

• Global Academy of Agriculture and Food Security, The Royal (Dick) School of Veterinary Studies, University of Edinburgh, UK
• School of Geosciences, University of Edinburgh, UK
• Institute of Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Karlsruhe Institute of Technology, Germany
• Institute for Geography and Geo-ecology, Karlsruhe Institute of Technology, Germany
• Highlands Rewilding Ltd., UK

Short Summary

This study presents a novel coupled land-use change and ecohydrological model, linking SWAT+ and CRAFTY, to simulate agricultural production and water use in arid multi-seasonal systems under climate change scenarios. Applied to Egypt, the model projects varying crop yield responses and improved water use efficiency, particularly under high CO2 emission futures, demonstrating the value of integrated biophysical and socioeconomic feedback for adaptation.

Objective

• To develop and apply a novel coupled land-use change and ecohydrological model to simulate the interactions between climate, water, crops, and human decision-making in arid agricultural systems.
• To assess potential crop yield and water use trajectories under various climate change scenarios (to 2099) in Egypt, providing insights into future agricultural productivity and water demand.
• To demonstrate the benefit of coupling biophysical and agent-based models by capturing how shifts in potential yields, driven by elevated CO2 and warming, shape land-use change and adaptive management.

Study Configuration

• Spatial Scale: Egypt, specifically the Nile Delta, Nile Valley, and Mediterranean regions, covering 28 % of Egypt’s land area and 92 % of its cultivated land. Model resolution is 900 m grid cells.
• Temporal Scale: Daily timestep for SWAT+ simulations; annual simulations for CRAFTY and coupled model from 2020 to 2100.

Methodology and Data

• Models used:
  • SWAT+ (Soil and Water Assessment Tool Plus): Semi-distributed watershed ecohydrological model, simulating crop growth, hydrology, and irrigation water use.
  • CRAFTY (Competition for Resources between Agent Functional Types): Agent-based model simulating land-use decisions and competition among Agent Functional Types (AFTs).
• Data sources:
  • Global datasets: MERIT DEM (90 m), ESA Landcover (300 m), DSOLMap (250 m), Lake shapefile, Streamflow data, CO2 concentration (2020–2100), Soil grid depth to bedrock (250 m), GLHYMPS, bias-corrected and downscaled MRI-ESM2-0 climate model data (0.25° resolution daily for rainfall, min/max temperature, relative humidity, solar radiation, wind speed).
  • National datasets (Egypt): Annual land use and cropping pattern statistical reports (CAPMAS, 2025), governorate-level yield and water use data (CAPMAS, 2025), subnational Human Development Index indicators (Smits and Permanyer, 2019), 1 km² gridded GDP and population datasets (Wang and Sun, 2022; Wang et al., 2022), road infrastructure data (Meijer et al., 2018), per capita membership in agricultural cooperatives (CAPMAS, 2025), Gini index (OAMDI, 2023), tractors per feddan (CAPMAS, 2025).
  • Modelled datasets: Potential yield calculated from the SWAT+ model at 900 m resolution.

Main Results

• Yield Responses: C3 crops (e.g., wheat, seasonal fodder, alfalfa) show significant yield increases under elevated CO2 concentrations, with fodder crops increasing by 117-119 % and wheat by over 43 % under RCP8.5 by 2099. C4 crops (e.g., maize) show modest increases or slight reductions, especially under high CO2 scenarios. Overall, RCP8.5 leads to the greatest average yield gains (25 % increase across all crops), while RCP2.6 shows minimal change (4 % increase).
• Water Use Efficiency (WUE): WUE consistently improves across all climate scenarios, with the most substantial improvements under RCP8.5, leading to an average 69 % reduction in water use per tonne of yield. Alfalfa and seasonal fodder show the greatest improvements (85-88 % reduction). RCP2.6 shows minimal WUE improvement (4 %).
• Spatial Yield Variation: Maize yields decline by up to 25 % in southern Egypt by the late 21st century, while wheat yields increase across all regions and scenarios, with up to 75 % gains in currently uncultivated areas of the Western Desert.
• Land Use Change: The coupled model demonstrates dynamic land-use shifts. Seasonal fodder, wheat, sugarcane, and main vegetables show increased production under higher emission scenarios (RCP4.5, RCP6.0, RCP7.0, RCP8.5). Cropped areas for seasonal fodder, wheat, and main vegetables show gradual declines despite rising production. Abandoned land declines sharply after 2080 under RCP8.5, reaching 21,708 ha by 2099, while in other scenarios, it increases gradually (43,092 ha to 49,896 ha). Reclamation of unmanaged land occurs rapidly in the early years (939,600 ha to 650,000-700,000 ha by 2025) and then stabilizes.
• Model Calibration: SWAT+ calibration showed acceptable performance, with average R² of 0.52 and NRMSE of 43.98 % for yield during calibration, and R² of 0.25 and NRMSE of 108.19 % during validation. PBIAS remained below 15 % during validation.

Contributions

• Presents a novel coupled land-use change-ecohydrological model (SWAT+ and CRAFTY) for multi-seasonal arid agricultural systems, explicitly integrating biophysical and socioeconomic responses.
• Incorporates a multi-seasonal representation of crop and irrigation processes, allowing land-use change and irrigation behavior to evolve interactively.
• Utilizes openly available global datasets, making the approach transferable to data-scarce, water-limited regions beyond the Egyptian case study.
• Demonstrates that even with static socioeconomic conditions, the coupled model reveals significant land-use dynamics (abandonment, reclamation, cropping pattern shifts) in response to climate-driven changes in potential yields, enhancing the interpretation of biophysical responses.
• Provides insights into the complex interplay of CO2 fertilization effects, warming, and water use efficiency in arid agricultural systems, highlighting the potential for both gains and declines in crop yields and overall improvements in water use efficiency.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Citation

@article{Sattar2025coupled,
  author = {Sattar, Aimen and Moulds, Simon and Brown, Calum and Rounsevell, Mark and Alexander, Peter},
  title = {A coupled land use change-ecohydrological model for multi-seasonal arid agricultural systems: an Egyptian case study},
  journal = {Environmental Modelling & Software},
  year = {2025},
  doi = {10.1016/j.envsoft.2025.106845},
  url = {https://doi.org/10.1016/j.envsoft.2025.106845}
}