Investigating Drought Duration-Severity-Intensity Characteristics Using the Standardized Precipitation-Evapotranspiration Index: Case Studies in Drought-Prone Southeast Queensland

Abstract

Drought characterization is crucial for identifying impacts on irrigation, agriculture, hydrologic engineering, and water resources management. This case study demonstrates the scientific relevance of the standardized precipitation-evapotranspiration index (SPEI) as a robust drought metric that incorporates influence of supply-demand balance. Using long-term data, the SPEI was calculated at multiple timescales to identify historical water deficit periods in selected drought-prone case study regions in southeast Queensland, Australia. The drought duration (D; number of months with continuously negative SPEI representing below average water resources), severity (S; accumulated negative SPEI in a drought-identified period), intensity (I; minimum SPEI), and return periods were enumerated for iconic dry events over multiple (1-, 3-, 6-, 9-, 12-, and 24-month) timescales. The SPEI was evaluated with corresponding drought indicators (precipitation and soil moisture) and climatological Rainfall Anomaly Index to yield drought severity information from a meteorological perspective. The results showed disparities in duration, severity, and intensity (D–S–I) of different droughts among the case study regions; reaffirming the significance of SPEI for regional drought impact assessment. Accordingly, this case study advocates SPEI as a convenient metric for detecting drought onsets and terminations, including drought ranking and recurrence evaluations that are vital statistics in hydrologic engineering.