Temporal-spatial evaluation of the drought process and its effects on vegetation changes in Fars province

Drought is a mysterious phenomenon whose effects, unlike earthquakes and floods, are not sudden and cover wide areas. Understanding this phenomenon can increase the resilience of human societies and reduce its consequences. Otherwise, drought leads to imbalance and anomaly in social and ecological systems. In this research, Fars province (9 selected stations) has been selected to investigate the drought during a statistical period of 28 years (1994-2021), and the SPI and PNPI indices and the NDVI index have been used to verify the validity of these indices and the consequences of drought. The results showed that climatic droughts continued during this period with the difference that the index (SPI) shows the severity of drought better and emphasizes minimum ranges, and the PNPI index displays the maximum ranges while providing a better classification of drought severity. According to the results, the severity of droughts is inclined from the south to the northern parts of the region. The results of the vegetation cover index showed that there are many changes in the density and extent of vegetation cover during the period of about 30 years, which confirms the evaluation of the drought indicators in this research.