Gasmi et al. (2026) Emerging climate–yield re-coupling in overexploited date palm oases: Satellite evidence from a 22-year temporal decoupling index in southern Tunisia

Identification

• Journal: Agricultural Water Management
• Year: 2026
• Date: 2026-06-24
• Authors: Tarek Gasmi, Ramzi Guesmi, Slim Abdelbari, Soura Boulaares, Sajeda Albarghati
• DOI: 10.1016/j.agwat.2026.110557

Research Groups

• University of Manouba, Tunisia
• University of Jendouba, Tunisia
• University of Sousse, Tunisia
• MUST University, Tunisia
• DataDoIt, Tunisia

Short Summary

This study investigates the impact of groundwater depletion on date palm oases in southern Tunisia using satellite and climate data. The results show that the irrigation buffer is still largely effective but the resource sustaining it is disappearing.

Objective

• Investigate whether satellite earth observation can detect the onset of irrigation-buffer degradation in aquifer-dependent oases.
• Quantify the groundwater depletion financing the observed production growth.
• Introduce a temporal decoupling index to track how the sensitivity of per-hectare yield to atmospheric water demand evolves over time.

Study Configuration

• Spatial Scale: Southern Tunisia, specifically the four date-palm-producing governorates of Tozeur, Kébili, Gafsa, and Gabès.
• Temporal Scale: 2002–2024

Methodology and Data

• Models used:
  • Ridge regression (regularised linear)
  • Random Forest (non-linear interactions)
  • XGBoost (gradient-boosted ensemble)
• Data sources:
  • Satellite earth observation (MODIS NDVI, land surface temperature, precipitation, and terrestrial water storage)
  • Atmospheric reanalysis (ERA5-Land)
  • Ground-based aquifer accounting
  • Agronomic production records

Main Results

• Satellite-based yield forecasting fails in irrigated oases.
• GRACE reveals accelerating groundwater depletion over the study period.
• The temporal decoupling index detects a thinning irrigation buffer in Tozeur and Kébili.

Contributions

• This study provides evidence of the onset of irrigation-buffer degradation in aquifer-dependent oases, detected by satellite earth observation before any decline appeared in the production record.
• The results highlight the importance of tracking buffer integrity rather than predicting yields using climate signals.

Funding

• This research was funded by [insert funding projects, programs, and reference codes].

Citation

@article{Gasmi2026Emerging,
  author = {Gasmi, Tarek and Guesmi, Ramzi and Abdelbari, Slim and Boulaares, Soura and Albarghati, Sajeda},
  title = {Emerging climate–yield re-coupling in overexploited date palm oases: Satellite evidence from a 22-year temporal decoupling index in southern Tunisia},
  journal = {Agricultural Water Management},
  year = {2026},
  doi = {10.1016/j.agwat.2026.110557},
  url = {https://doi.org/10.1016/j.agwat.2026.110557}
}