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

Abstract We assessed changes in daily precipitation extremes for the Fiji Islands from 1905 to 2021 using quality-controlled and homogenized series. We employed a set of 23 precipitation indices that span a wide variability of daily precipitation characteristics, including the frequency, magnitude, and duration. Changes in extreme events were assessed using the non-parametric 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 precipitation indices, as evidenced by a significant intensification of the intensity of extreme precipitation events (e.g., rx1day and rx5d) for the period 1905–2021. Most of these observed changes were statistically non-significant ( p > 0.05), especially during the period 1960–2021. Changes in precipitation indices like metrics for days with more than a certain amount of precipitation (i.e., dr1mm and dr3mm) showed varied patterns across different time periods. Spatially, stations on the leeward side of Viti Levu showed drier conditions compared with those on the windward side, suggesting strong spatial variability between the windward and leeward sides. 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.