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Abstract Understanding regional rainfall trends is vital to address the effects of climate change and guarantee water and food security. The present study analysed various statistical methods to examine spatio-temporal variations and changes in the distribution of regional rainfall from 1981 to 2022. Statistical analysis of the decadal rainfall data reveals a gradual increase in trend. The spatio-temporal analysis indicated divergent rainfall trends: 31% and 36% increases in the South and North Andaman districts, respectively, and a stable distribution in the Nicobar district. Notably, significant increases and decreases in rainfall events occurred at least once in a decade in the North Andaman and the Nicobar districts. The analysis of the coefficient of variance showed that while annual and monsoon rainfall exhibited low variability, non-rainy seasons showed significant variability, suggesting a considerable seasonal variation. Finally, the rainfall seasonality trends show clear spatial differences across the Andaman Islands. Over recent decades, rainfall concentration has become less regular, with decreases of 24% in South Andaman and 33% in North Andaman. Unlike this, in the Nicobar district, homogeneity persists throughout the whole period under study. Temporal analysis gives a significant shift (p < 0.05) toward more irregular patterns in recent decades, indicating an increase in hydroclimatic variability associated with climate change. The study identified heteroscedasticity patterns that underscore the non-stationary nature of current precipitation regimes.
Mookiah et al. (2026) studied this question.