Investigation of Drought Indices in Golestan, Mazandaran, and Guilan Provinces during a 10-Year Period (2009-2019)

One of the most important effects of climate change is drought, a condition that is caused by a long period without rainfall; however, the determination of the time and place of its beginning is difficult. Many researchers have attempted to develop the necessary techniques to analyze and monitor drought indicators and their impact on the climate. In this regard, the present study aimed to investigate the drought indices for 10 years in a descriptive cross-sectional design in Golestan, Mazandaran, and Guilan provinces.

In the present descriptive cross-sectional study, different drought indices were determined, such as standard precipitation index (SPI), decile index (DI), number index (ZCI), Chinese z index (CZI), and modified Chinese z index (MCZI). Finally, DIP software was used for data analysis(version: 2.0), and The obtained indicators were compared with the standards.

Based on the results, the studied indicators had a similar upward trend in all stations of Mazandaran and Golestan provinces for 10 years. However, there was the possibility of drought in Guilan province in summer according to CZI and MCZI indices, compared to the other two provinces since the average monthly rainfall was lower than that of the other two provinces. According to the MCZI index, Guilan and Mazandaran provinces had their driest months in March (-1) and April (-0.8), respectively, which could be due to the effects of climate change.

Results of this study can be useful for the determination and prediction of the future conditions of these areas and the provision of early warnings of drought, especially in areas with water scarcity.