Journal of Drought and Climate change Research

Spatio-Temporal Dynamics of Drought along a Climatic Gradient in Central Zagros: A Multi-Scale Assessment Using IDSPI and SPEI

Articles in Press

Document Type : Original Article

Authors

HamidReza Naji 1
Mehdi Heydari 2
Marzban Faramarzi 3
Forough Soheili 2

1 Department of Forest Sciences, Ilam University, Ilam

2 Department of Forest Sciences, Faculty of Agriculture and Natural Resources, Ilam University, Ilam

3 Rangeland and Watershed Management Group, Faculty of Agriculture and Natural Resources, Ilam University, Ilam

https://doi.org/10.22077/jdcr.2026.11639.1262
Abstract
This research examines the spatio-temporal evolution of drought dynamics across a climatic gradient in the Zagros forests throughout a three-decade period (1993–2022). To ensure analytical precision, the region was stratified into five distinct climatic classes (arid, semi-arid, Mediterranean, sub-humid, and very humid), utilizing the SPEI index across four temporal scales. Additionally, the Integrated Drought Severity-Persistence Index (IDSPI) was developed to concurrently assess the magnitude, duration, and persistence of extreme drought events. Our findings demonstrate a statistically significant decline in precipitation across all climatic zones. The semi-arid climate emerged as the most vulnerable, characterized by the highest cumulative intensity. Notably, IDSPI analyses indicate that during the terminal phase of the study period (2021–2022), extreme droughts (SPEI ≤ −2.0) migrated from arid regions toward Mediterranean and humid zones. This shift signifies a diminishing resilience of humid ecosystems to prolonged hydroclimatic shocks. Ultimately, this study confirms that drought in the Zagros forests has transitioned from a localized occurrence in arid lands to a systemic crisis pervading humid regions. These insights highlight the imperative for a critical re-evaluation of water resource management frameworks within the humid zones of the Zagros.

Keywords

Hydroclimatic variability
trend analysis
extreme events
ecosystem resilience
Zagros
Subjects
Journal of Drought and Climate change Research

Articles in Press, Accepted Manuscript
Available Online from 30 September 2026

  • Receive Date 07 July 2026
  • Revise Date 18 September 2026
  • Accept Date 30 September 2026

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