چكيده انگليسي :
Drought is a complex phenomenon that is aggravated by climate change, and factors such as the increase in global temperature associated with climate change affect precipitation patterns and water cycle processes, which ultimately increase the occurrence and severity of drought. To effectively deal with and adapt to these challenges, it is very important to identify the prevailing climatic factors that lead to drought events; Therefore, it is necessary to check the changes in the climate using some indicators. In this research, with the aim of investigating the effects of drought during a 24-year statistical period in Jiroft Plain, using the SPI meteorological drought index and the 23-year statistical period of the SDI hydrological index in the time scales of 3, 6, 9, 12, 18, 24 and 48 month and the relationship between these two types of drought has been investigated. For this purpose, the climatic data (rainfall) of Cheshme-Shah, Dehroud, Doroggoiyeh, Qala-Rigi, Jiroft, Kohnak-Shibani, Kanaruiye, Miandeh, Saghdar and Zarin stations in the joint statistical period of 1996 to 2020 of the hydrometric stations of Dehroud, Qala-Rigi, Hossein-Abad, Kohnak-Shibani, Kanaroiyeh, Kaldan and Zarin with the statistical period from 1993 to 2016 have been used. Geostatistical methods were used to prepare the map of the drought condition of Jiroft Plain, and based on the error value obtained, the IDW method was suitable for showing the distribution of drought in the region; Finally, the Mann-Kendall statistical test was used to determine the relationship between drought, as well as for the spatial and temporal analysis of drought and to determine the trend. The results of the SPI index in the short and long term period showed that in the weather stations in the years (2000, 2001, 2004, 2006, 2008, 2016, 2017 and 2018) a very severe drought has occurred, and according to the classification of the SPI index, the amount of precipitation in these years has been much less than normal. On the other hand, the results of the SDI index for the hydrometric stations showed that in the years 1993, 2003, 2004, 2007, 2008 and 2010 and the months of March, December and August, the flow was less than normal and there were dry periods. Pearson's correlation test was used to show the relationship between two indicators, which showed that there is the highest correlation between the time scales of 12, 24 and 48 months. It showed that there is no correlation between meteorological and hydrological drought index in all stations. In other words, when there was a hydrological drought, the meteorological drought index showed other conditions. Based on the graphs, it is clear that in these stations, the dry periods of Baran-Sajni stations are different from those of Dubai. One of the reasons for these differences is the origin of the currents upstream of the hydrometric stations, which creates a base current, according to the results of the changes in the SPI and SDI indices, it was found that the stations at the two levels of 0.95 and 0.99 with a lower Z value - equal 2/08- have significant differences with each other. In general, it can be concluded that the changes in the river flow in the region after a time delay are affected by the rainfall conditions in the region.
