Evaluation of Different Drought Indices to Find the Mos t Applicable Index (Case Study:Aleshtar Plain)

One of the main challenges in monitoring drought is determining an index that is highly reliable based on the monitoring objective. Assessment and drought monitoring is considered one of the most important tools for drought management, as it can determine the start and end, spatial extent, and intensity of its effects. It can also help in identifying the need for drought response plans and determining the formation time of a drought monitoring and response committee. In this study, the meteorological drought was investigated using drought indices such as ZSI, MCZI, CZI, PN, DI, and SPI in the Aleshtar plain. Daily precipitation values from three stations, Aleshtar, Kaka Reza, and Sarabsead Ali, were collected for the period 2001-2021. After analyzing the annual precipitation trend at each station, the duration and maximum severity of drought were determined using meteorological drought indices. To evaluate the performance of these indices and select the most applicable index for the region, the minimum hypothesis was used. According to the results, the CZI index performed better than the other indices by correctly estimating one out of four cases. following Spearman's correlation between precipitation parameters and drought indices was investigated, the results showed a significant correlation between all indices at all stations except for MCZI, which had poor performance. Finally, considering the total scores, the CZI index, which obtained 21 points out of the total tests, was selected as the superior index for the region. The SPI and ZSI indices also yielded satisfactory and accurate results in this area.