Alhathloul (2026) Spatiotemporal Trends and Abrupt Changes in Annual Potential Evapotranspiration and Water Balance over Saudi Arabia

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Identification

• Journal: Water
• Year: 2026
• Date: 2026-03-19
• Authors: Saleh H. Alhathloul
• DOI: 10.3390/w18060725

Research Groups

Not available from the provided text.

Short Summary

This study investigates the interannual variability, long-term trends, and abrupt regime shifts in potential evapotranspiration (PET) and water balance (WB) across Saudi Arabia from 1985 to 2022. It reveals a widespread increase in atmospheric evaporative demand and declining WB, indicating an intensifying water deficit, with a significant hydroclimatic regime shift identified in the late 1990s.

Objective

• To investigate the interannual variability, long-term trends, and abrupt regime shifts in annual potential evapotranspiration (PET) and water balance (WB) across Saudi Arabia.

Study Configuration

• Spatial Scale: Across Saudi Arabia, analyzed at both regional and multi-station scales.
• Temporal Scale: 38 years (1985–2022), focusing on interannual variability and long-term trends.

Methodology and Data

• Models used: A temperature-based approach for estimating potential evapotranspiration (PET). Water balance (WB) was calculated as the difference between precipitation and PET.
• Data sources: Multi-station observational data. Non-parametric statistical methods were used for trend assessment, and Pettitt’s change-point test for regime shifts.

Main Results

• Widespread and spatially coherent increase in atmospheric evaporative demand, with predominantly positive PET trends at both regional and station scales.
• Persistently negative and increasingly declining water balance (WB) values, indicating a long-term intensification of water deficit across much of Saudi Arabia.
• Spatial patterns of PET and WB closely follow gradients in energy availability and temperature, confirming the dominant influence of warming-driven processes.
• A statistically significant regional hydroclimatic regime shift was identified during the late 1990s, characterized by an abrupt increase in PET and a concurrent deterioration of WB, marking the onset of a more water-limited climatic regime.
• At the station scale, the timing and significance of detected change points displayed pronounced spatial heterogeneity, influenced by local climatic and geographic factors.
• Increasing evaporative demand, rather than precipitation variability alone, has become a primary control on water availability across Saudi Arabia.

Contributions

• Demonstrates that increasing evaporative demand, driven by warming, is a primary control on water availability in Saudi Arabia, rather than solely precipitation variability.
• Highlights the critical importance of explicitly accounting for hydroclimatic non-stationarity in water resource assessment and long-term planning, particularly in arid environments under continued warming conditions.

Funding

Not available from the provided text.

Citation

@article{Alhathloul2026Spatiotemporal,
  author = {Alhathloul, Saleh H.},
  title = {Spatiotemporal Trends and Abrupt Changes in Annual Potential Evapotranspiration and Water Balance over Saudi Arabia},
  journal = {Water},
  year = {2026},
  doi = {10.3390/w18060725},
  url = {https://doi.org/10.3390/w18060725}
}