Mapping Meteorological Drought Periods in South Sulawesi Using the Standardized Precipitation Index with the Power Law Process Model

Abstract

A drought is when reduced rainfall leads to a water crisis, impacting daily life. Over recent decades, droughts have affected various regions, including South Sulawesi, Indonesia. This study aims to map the probability of meteorological drought months using the 1-month Standardized Precipitation Index (SPI) in South Sulawesi. Based on SPI, meteorological drought characteristics are inversely proportional to drought event intensity, which can be modeled using a Non-Homogeneous Poisson Process, specifically the Power Law Process. The estimation method employs Maximum Likelihood Estimation (MLE), where drought event intensities are treated as random variables over a set time interval. Future drought months are estimated using the cumulative Power Law Process function, with the β and γ parameters more significant than 0. The probability of drought months is determined using the Non-Homogeneous Poisson Process, which models event occurrence over time, considering varying intensities. The results indicate that, of the 24 districts/cities in South Sulawesi, 14 experienced meteorological drought based on the SPI and Power Law Process model. The estimated number of months of drought occurrence in the next 12 months is one month of drought with an occurrence probability value of 0.37 occurring in November in the Selayar, Bulukumba, Bantaeng, Jeneponto, Takalar and Gowa areas; in October in the Sinjai, Barru, Bone, Soppeng, Pinrang and Pare-pare areas; as well as in December in the Maros and Makassar areas.

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