Abstract—One of the major challenges faced by engineer and hydrologist is inadequate or non-availability of hydrological and meteorological data to properly design, operate and plan water resources against extreme rainfall event. Such data would be needed for the development of Rainfall Intensity-Duration-Frequency (IDF) curves for design of storm drainage in urban systems. This study analysed the daily rainfall data collected from Nigeria Meteorological Agency (NIMET) Oshodi, Lagos for eight major towns in five state in South Western Nigeria over a period of twenty nine (1984-2012) years. The data was processed and analysed using Microsoft Excel spread sheet to generate series of peak annual rainfall. The record of duration of rainfall data was not available and as a result a USDA generalised accumulated rainfall curve for storm type A was adopted for short duration interval. The rainfall intensity values were calculated for duration of (15, 30, 45, 60, 90, 120 and 240 minutes) to estimate returns period of (2, 5, 10, 20, 50, 100 and 200 years) using Gumbel Extreme Value Type 1 distribution. The non-parametric Kolmogorv-Smirvov test and the Chi-Square test were used to confirm the appropriateness of the fitted distributions for the locations. The IDF curves were developed for the towns and recommended for the design of storm drainage.
Index Terms—Rainfall intensity, return period, gumbel distribution, intensity-duration-frequency-curve.
Awofadeju A. S. and Akanni A. O., Oguntayo A. A. are with the Osun State Polytechnic Iree, Osun State, Nigeria (e-mail: awas064@gmail.com, ayoakanni1@gmail.com).
Ojeleke T. A. is with the AWAS Associates, Nigeria (e-mail: toyinwealthreal@yahoo.com).
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Cite: Awofadeju A. S., Akanni, A. O., Ojeleke T. A., and Oguntayo A. A., "Development of Rainfall Intensity-Duration-Frequency Curves for South Western Nigeria," International Journal of Engineering and Technology vol. 10, no. 4, pp. 373-379, 2018.
