Development of Intensity–Duration–Frequency Curves for Surat City Incorporating Daily Data

Abstract

One of the most important hydrologic tools used in design of hydraulic and water resource projects and flood control structures in urban areas by hydraulic engineers is the intensity–duration–frequency (IDF). IDF curves are the representation of relationship between duration, intensity and return period (frequency) of rainfall, which are obtained from a series of analysis of observed rainfall data. In most part of India, short duration rainfall is scarce and only daily rainfall data are available. In such case, it is required to convert the daily rainfall data into hourly using India Metrological Department (IMD) formulas. Assessing the adverse effects of climate change and adapting to them is one way to reduce vulnerability caused, specifically confronting city floods. Since, the rainfall IDF curves are used in the design of water resources projects, in order to have safe and economically stable hydraulic structures. In the present study, the rainfall data of 119 years (1901–2020) were collected from IMD. The aim of this study is to obtain IDF curves having durations of 15 min, 30 min, 45 min, 1 h, 2 h and 3 h for the Surat city. The maximum rainfall intensity curves of different durations like 15 min, 30 min, 45 min, 1 h, 2 h and 3 h are derived from daily rainfall data using IMD formula. It was found that rainfall intensity of 60 mm/h can be used in the design of water resources project and an equation is obtained which can be used to compute daily maximum intensity at any given return period. The developed curves are useful for planning and design of urban storm water and water conservation measures for the Surat city.