Evaluation of extreme rainfall occurrences using standard precipitation index (SPI)

The main objective of this study is to investigate The Standard Precipitation Index (SPI), a commonly used method for determining extreme rainfall occurrences as well as gauging the duration and severity of droughts. To pinpoint exceptional rainfall events in a specific area, a methodology was provided in this paper for calculating the SPI for different periods of time and thresholds. Overall, the study highlights the potential of using the SPI to improve our understanding of extreme rainfall events. The Standard Precipitation Index (SPI) is utilized to analyze the monthly precipitation data for several selected rain gauge stations between the years 1970 and 2014. The goal of this study is to keep an eye on the extremely moist conditions that may eventually result in floods. Precipitation index data from several rain gauge sites in Peninsular Malaysia are used to calculate SPI time series. Additionally, SPI readings for 3 months or less may usually be used for basic drought monitoring, values for 6 months or less may be useful for monitoring agricultural impacts, and values for 12 months or more may be useful for monitoring hydrological impacts. In this study, two states that are affected by monsoon season were selected, which are Johor and Kelantan. Two rain gauges stations were selected from these two states to calculate the SPI results. From this study, statistics of occurrence for dry and wet events in specified areas were determined based on the SPI readings for 3-month, 9-month, 12-month and 24-month.