Persistence and spatial-temporal variability of drought severity in Iran

Area of Science:

• Climatology and Environmental Science
• Hydrology and Water Resources Management

Background:

• Droughts pose significant risks to agriculture, economies, and ecosystems.
• Understanding drought persistence is crucial for developing effective prediction models.

Purpose of the Study:

• To investigate the persistence and spatial-temporal variability of drought severity in Iran's drylands.
• To determine relationships between drought severity, precipitation variation, aridity, and climatic factors.

Main Methods:

• Utilized monthly precipitation and temperature data from 44 synoptic stations (1989-2018).
• Applied the Standardized Precipitation Index (SPI), Dryland Index, and Hurst exponent (H) for analysis.
• Examined the influence of El Niño-Southern Oscillation (ENSO) on drought severity.

Main Results:

• Drought persistence (H > 0.5) was confirmed across all Iranian stations.
• The average persistence of drought severity (PDS) in Iran is 0.78, showing significant regional variations.
• An inverse relationship between precipitation variation and PDS was found in arid regions, while dry-subhumid areas showed higher PDS and increasing trends.

Conclusions:

• Droughts are a persistent feature in Iran with notable regional differences in severity and persistence.
• Climate variability, including ENSO, influences drought patterns spatially and temporally.
• Findings support the development of targeted drought management strategies for diverse Iranian drylands.