ارزیابی کارایی شاخص‌هایSPI و SPEI در پایش خشکسالی هواشناسی در استان تهران

occurrence of drought has had many effects on the agricultural sector. This phenomenon has caused negative effects on the management of water resources. Assessing and quantifying drought is one of the important components in water resources management. In recent decades, many indicators have been developed to quantify drought. Some of these indicators, such as SPI, in quantifying drought, are based on rainfall changes. On the other hand, many researchers have emphasized the importance of temperature variable on drought conditions. This approach has led to the creation of indices such as SPEI. In this research, the aim is to evaluate the efficiency of these two drought evaluation indicators in Tehran province. In order to evaluate the effectiveness of these two drought indicators, NDVI index, which shows the changes in humidity reduction at the vegetation level, has been used. Therefore, after receiving the required information of precipitation and evaporation and transpiration from the stations located in Tehran province, it was started to calculate the SPI and SPEI indices at the stations. Next, the NDVI index was prepared and extracted from the Modis sensor product. Then the relationships between the meteorological drought indices and the NDVI remote sensing index were extracted and the correlation coefficient was calculated for each of the indices. The results show that the SPI index has more sensitivity and compatibility than the SPEI index in Tehran province for drought assessment. It is suggested that the efficiency of these two indicators be investigated in all stations of the country.