M Satya Swarupa Rani, NVVS Durga Prasad and G Ramesh

This paper discusses a method for calculating the severity of meteorological droughts based on historical precipitation data as the primary criterion Monthly precipitation data from 1970 to 2020 were used to obtain Standardized Precipitation Index (SPI) values for Prakasam district, Andhra Pradesh. SPI has the ability to analyse the drought at various time scales and for a variety of applications. SPI is calculated at various time scales (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 etc. months). Time scales of one, two, and three months are effective for agriculture, while time scales of six, nine, and twelve months are useful for hydrology. A drought event occurs any time the SPI is continuously negative and reaches an intensity of -1.0 or less. The event ends when the SPI becomes positive. Each drought event, therefore, has a duration defined by its beginning and end, and an intensity for each month that the event continues. The annual SPI for Prakasam district was calculated from 1970 to 2020 to show the frequency of occurrence of dry and wet conditions. Temporal SPI graphs show that the maximum SPI value (extreme drought) occurred in the year 2018 in that year, the SPI value was -2.6. Furthermore, in severe and extreme drought years, SPI values indicated only moderate dryness rather than extreme dryness, with SPI values never falling below -2.5.Severe and moderate drought occurred in 1984, 2002 and 2014. Drought patterns were evaluated, yielding many interesting results on the variability of drought occurrence in the region. The study's findings are relevant to climate change studies in order to understand historical patterns and build future scenarios of drought occurrences.

DOI: 10.22271/phyto.2021.v10.i4Sa.14268

Pages: 17-23  |  406 Views  154 Downloads