Comparative Evaluation of Standardized Precipitation Index (SPI) and Effective Drought Index (EDI) for Meteorological Drought Detection over Bangladesh

Abstract

A good number of drought indices have been introduced and applied in different regions for monitoring drought conditions, but some of those areregion-specific and have limitations for use under other climatic conditions because of the inherently complex characteristics of drought phenomenon. Standardized Precipitation Index (SPI) indices are widely used all over the world, including Bangladesh. Although newly developed, studies havedemonstrated The Effective Drought Index (EDI) to perform better compared to SPIs in some areas. This research examined the performance of EDIto the SPI for detecting drought events throughout 35 years (1981 to 2015) in Bangladesh. Rainfall data from 27 meteorological stations acrossBangladesh were used to calculate the EDI and SPI values. Results suggest that the EDI can detect historical records of actual events better than SPIs. Moreover, EDI is more efficient in assessing both short and long-term droughts than SPIs. Results also indicate that SPI3 and the EDI indices havea better capability of detecting drought events in Bangladesh compared to other SPIs; however, SPI1 produced erroneous estimates. Therefore, EDI isfound to be more responsive to drought conditions and can capture the real essence of the drought situation in Bangladesh. Outcomes from this studybear policy implications on mitigation measures to minimize the loss of agricultural production in drought-prone areas. Information on severity leveland persistence of drought conditions will be instrumental for resource managers to allocate scarce resources optimally.