Alitane et al. (2026) Navigating water security in semi-arid regions: SWAT+-based analysis of climate change impacts in Morocco’s R’Dom watershed

Identification

• Journal: Modeling Earth Systems and Environment
• Year: 2026
• Date: 2026-03-31
• Authors: Abdennabi Alitane, Ali Essahlaoui, Mohamed Ouarani, Ahmed M. Saqr, Sabine Sauvage, Ann van Griensven
• DOI: 10.1007/s40808-026-02767-y

Research Groups

• International Water Research Institute (IWRI), Mohammed VI Polytechnic University (UM6P), Ben Guerir, Morocco
• Geoengineering and Environment Laboratory, Research Group “Water Sciences and Environment Engineering”, Geology Department, Faculty of Sciences, Moulay Ismail University, Meknes, Morocco
• Water and Climate Department, Vrije Universiteit Brussels (VUB), Brussels, Belgium
• Irrigation and Hydraulics Department, Faculty of Engineering, Mansoura University, Mansoura, Egypt
• Centre de Recherche sur la Biodiversité et l’Environnement, Institut national polytechnique de Toulouse (INPT), CNRS, Université de Toulouse (UPS), Toulouse, France

Short Summary

This study applied an integrated framework combining the Soil and Water Assessment Tool Plus (SWAT+) and the Statistical Downscaling Model (SDSM) to assess climate change impacts on water balance components in Morocco’s R’Dom watershed under various Representative Concentration Pathways (RCPs). The findings indicate a significant decrease in streamflow (43.00–52.20%) and increased evapotranspiration across all future scenarios, primarily due to heightened water stress.

Objective

• Assess future climate change scenarios using an integrated SWAT+ and SDSM framework.
• Analyze the impacts of climate change on water balance components, including precipitation, evapotranspiration, and discharge.
• Evaluate the contribution of the integrated modeling approach to achieving several Sustainable Development Goals (SDGs).

Study Configuration

• Spatial Scale: R’Dom watershed, a sub-basin of the Sebou River Basin in northern Morocco, covering approximately 1,970 km². The watershed was delineated into 17 subbasins and 1,750 Hydrological Response Units (HRUs).
• Temporal Scale:
  • Warm-up period: 2000–2001
  • Baseline/Historical period: 2002–2013 (for SWAT+ calibration/validation and climate comparison)
  • Future projection periods:
    • Short-term (ST): 2014–2043
    • Medium-term (MT): 2044–2071
    • Long-term (LT): 2072–2100
  • Climate Scenarios: Representative Concentration Pathways (RCPs) 2.6, 4.5, and 8.5.

Methodology and Data

• Models used:
  • Soil and Water Assessment Tool Plus (SWAT+) for hydrological modeling.
  • Statistical Downscaling Model (SDSM) for downscaling Global Climate Model (GCM) outputs.
  • Canadian Earth System Model (CanESM2) from CMIP5 for GCM projections.
• Data sources:
  • Topography: 30 m Digital Elevation Model (DEM).
  • Land Use/Land Cover (LULC): Global LULC based on Sentinel-2.
  • Soil: Data compiled from the National Institute of Agronomic Research.
  • Observed Discharge: Monthly observed discharge data from 2002 to 2013 at the Souk Elhad outlet.
  • Historical Weather Forcings: Daily precipitation and temperature from the Climate Forecast System Reanalysis (CFSR) for 2000–2013.
  • Large-scale Atmospheric Predictors: NCEP-NCAR reanalysis dataset (for SDSM).
  • Local Meteorological Data: Daily observed weather data from local meteorological stations (for SDSM calibration).

Main Results

• SWAT+ Model Performance: The model showed good reliability with R² values of 0.77 (calibration) and 0.70 (validation), Nash–Sutcliffe Efficiency (NSE) values of 0.60 (calibration) and 0.72 (validation), Root Mean Square Error (RMSE) values of 1.90 m³/s (calibration) and 4.90 m³/s (validation), and Pbias values of 18% (calibration) and 24% (validation).
• Precipitation Changes: Projected a general decline under RCP 2.6 (steepest reduction of -3.33% in the short-term). Modest increases were observed under RCP 4.5 and RCP 8.5 in some periods (e.g., +0.64% under MT-RCP 4.5). Reductions were most pronounced during the dry season (June–August).
• Temperature Changes: Consistent rise across all scenarios and periods, with the most significant warming observed in the long-term under RCP 8.5 (+1.65 °C). Greater warming was projected during summer months.
• Evapotranspiration Changes: Consistent increase across all RCPs and periods. Notable increases under RCP 8.5 were 11.17% (ST), 10.22% (MT), and 7.42% (LT). Moderate increases under RCP 4.5 were 9.29% (ST), 9.39% (MT), and 9.36% (LT). Increases were more pronounced during summer months.
• Streamflow (Discharge) Changes: A consistent and marked decline was projected across all scenarios and periods:
  • RCP 2.6: Decreases of 47.67% (ST), 48.44% (MT), and 45.63% (LT).
  • RCP 4.5: Decreases ranging from 44.23% (ST) to 43.00% (LT).
  • RCP 8.5: Decreases of 47.72% (ST), 47.93% (MT), and 52.20% (LT).
  • The largest declines occurred during the dry season.
• Water Balance Components (Mean Annual Changes): Precipitation showed declines (1.92% to 7.17%), surface runoff decreased significantly (exceeding 70% in most scenarios), evapotranspiration increased (5% to 9%), lateral flow experienced substantial declines (up to 92%), and water yield decreased (47% to 94%).
• Spatial Variability: Southern and central regions of the watershed were identified as most vulnerable, exhibiting the most significant reductions in precipitation and highest increases in evapotranspiration.

Contributions

• First-time application of an integrated SWAT+ and SDSM framework to assess climate change impacts on water resources in the R’Dom watershed, Morocco.
• Provides a scalable and transferable hydrological modeling framework applicable to other vulnerable semi-arid watersheds globally.
• Offers new scientific insights for developing adaptive water management strategies and resilience planning.
• Quantitatively evaluates the contribution of the integrated modeling approach to achieving multiple Sustainable Development Goals (SDGs), specifically contributing 25% to SDG 6 (Clean Water and Sanitation) and 40% to SDG 13 (Climate Action).

Funding

This research did not receive any external funding.

Citation

@article{Alitane2026Navigating,
  author = {Alitane, Abdennabi and Essahlaoui, Ali and Ouarani, Mohamed and Saqr, Ahmed M. and Sauvage, Sabine and Griensven, Ann van},
  title = {Navigating water security in semi-arid regions: SWAT+-based analysis of climate change impacts in Morocco’s R’Dom watershed},
  journal = {Modeling Earth Systems and Environment},
  year = {2026},
  doi = {10.1007/s40808-026-02767-y},
  url = {https://doi.org/10.1007/s40808-026-02767-y}
}