Document Type : Research Paper
Authors
1 Department of Nature Engineering, Faculty of Natural Resources and Environment, Islamic Azad University, Science and Research Branch, Tehran, Iran.
2 Department of Drought and Climate Change, Soil Conservation and Watershed Management Research Institute (SCWMRI) AREEO, Tehran, Iran.
3 Department of Forest, Range and Watershed Management, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran
Abstract
Objective: Drought is one of the climatological phenomena that affect the vast majority of Iran, including Fars Province, in terms of metrological, hydrological, agricultural and socio-economical aspects. Quantitative description and monitoring of this phenomenon requires the utilization of drought indices.
Research Methodology: To evaluate various drought indices in the Fars province, temperature, precipitation, and evaporation data of 113 stations in and close to the province (including synoptic, climatological stations and rain gauge stations) were collected and analyzed for 51 years (1966-2016). Additionally, 9 drought indices including SPEI, SIAP, DI, SPI, PN, MCZI, CZI, RDI and ZSI were employed. After ensuring data randomness, homogeneity, and normality, the three evaluation methods of minimum rainfall, normal distribution, and cross-correlation were utilized to select the most efficient drought index.
Findings: The SPEI index has the lowest difference between different drought classes compared to other indices based on the normal distribution method. According to the cross-correlation method, ZSI index has the highest correlation and similarity with the SPI index. Also, the minimum rainfall method showed that all indicators in the years of minimum rainfall show very severe and severe drought classes and this method cannot be a criterion for selecting the appropriate drought index.
Conclusion: In six years out of the 30-year period under evaluation, widespread severe drought had occurred across the province which include the years 1984, 1989, 1994, 2000, 2008, and 2009. Assessment of the indices for ten selected stations across the province indicated the two SIAP and RAI indices to yield similar outcomes.
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