Abstract
<title>Abstract</title> <p>Small Island Developing States (SIDS) face growing flood risks from short‑duration, high‑intensity rainfall, yet many lack the detailed rainfall analyses needed for resilient stormwater planning. This study provides the first integrated assessment of rainfall trends, extreme rainfall behaviour, and Intensity–Duration–Frequency (IDF) relationships for Malé, Maldives, using 31 years of hourly rainfall data (1993–2024). Trend detection was conducted using the Mann–Kendall test and Theil–Sen slope estimator, while extreme rainfall characteristics were analysed using the Gumbel Extreme Value Type I distribution. IDF curves were developed through power‑law fitting across multiple durations and return periods. Results show strong interannual variability in annual rainfall totals, ranging from about 1300 mm to 2700 mm, but no statistically significant long‑term trend in annual rainfall or 24‑hour annual maxima. However, several wet‑season months display increasing rainfall tendencies, suggesting a shift in rainfall distribution within the year rather than an overall increase in total rainfall. This intra‑annual concentration elevates the likelihood of short‑duration drainage exceedance in Malé’s densely built, low‑lying environment. Extreme value analysis produced a 100‑year, 24‑hour design rainfall depth of 216.9 mm, consistent with tropical coastal climates, while IDF curves show steep increases in intensity for short durations, with rare, high‑return‑period events reaching up to 3.94 mm/min. Overall, the findings indicate that flood risk in Malé is driven more by rainfall intensity and temporal clustering than by long‑term changes in annual rainfall volume. The updated IDF curves and trend insights provide essential inputs for stormwater design, flood mitigation, and climate‑resilient urban planning, forming a robust baseline for future non‑stationary analyses and hydrodynamic modelling in the Maldives.</p>