Changes in daily precipitation extremes over the Fiji Islands (1905-2021)

Abstract

Changes in daily precipitation extremes were assessed for the Fiji Islands from 1905 to 2021 using quality-controlled and homogenized series. A set of 23 daily precipitation indices, spanning a wide variability of daily precipitation characteristics, including the frequency, magnitude and the duration, were employed. Changes in extreme events were assessed using the nonparametric Kendall’s Tau-based slope estimator, while the significance of these changes was tested using the Mann Kendall statistic at the 95% confidence interval (p < 0.05). Results are presented for different time periods over the study domain, including 1905–2021, 1935–2021, and 1960–2021. Results suggest a general increase in most of the daily precipitation indices, as evidenced by a significant trend in the intensity of extreme precipitation events (rx1day and rx5d) for the period 1905–2021, albeit with a strong spatial and temporal variability. Most of these observed changes were statistically non-significant (p > 0.05). Stations on the leeward side of Viti Levu showed drier conditions, compared with those on the windward side. Changes in daily precipitation indices like dr1mm and dr3mm show varied patterns across different time periods, with substantial spatial variability between windward and leeward sides of Viti Levu. Our findings can contribute to the development and planning of sustainable strategies to assure water security and adaptative responses to extreme events over the Fiji Islands. Also, due to their isolation and relatively undisturbed ecosystems, our results can serve as early indicators of climate change and variability in remote oceanic islands.