Development of Station-Specific Intensity–Duration–Frequency (IDF) Curves for Bengaluru Metropolitan Region Using Homogeneity-Validated Rainfall Data.

Rapid urbanization has increased vulnerability to pluvial flooding in Indian metropolitan regions, highlighting the need for reliable rainfall Intensity-Duration-Frequency (IDF) relationships for urban drainage design.This study develops IDF curves for six rain-gauge stations in the Bengaluru metropolitan region Chikjala, Yelahanka, K R Pura, Beguru, Varthur, and Sarjapura using observed daily rainfall data from the department of Water Resource Development Organisation (WRDO) for the period of 1990-2024.Rainfall records were quality controlled; missing values were estimated using the normal ratio method.Short-duration rainfall depths were derived from daily maxima, and frequency analysis was carried out using Normal, Log-Normal and Gumbel extreme value distributions.Goodness-of-fit was assessed using chi-square, Anderson Darling Test and Kolmogorov-Smirnov tests, based on which the Gumbel distribution was identified as more suitable for extreme rainfall estimation.IDF curves were developed for return periods of 2, 5, 10, 25, 50, and 100 years, and empirical IDF equations were derived using nonlinear regression.The resulting station-specific IDF relationships provide robust baseline design inputs for urban drainage and flood mitigation planning in Bengaluru under present climatic conditions.