Development and comparison of different intensity duration frequency models for Calabar, Nigeria

Abstract

This paper is aimed at developing and comparing different intensity duration frequency models. Twenty three years peak rainstorm intensity data with their corresponding durations was collected from the Nigerian Meteorological Agency, Calabar, Nigeria. Microsoft Excel software was used to develop exponential, logarithmic and power intensity-duration-frequency models for return period (T) of duration-frequency models for return period (T) of between 2 years and 100 years using rainfall intensity data for durations of 2, 5, 10, 15, 30, 60, 120, 240 and 320 minutes. A comparison between the predicted results by the three models revealed that the logarithmic and power models gave R square values of between 0.022 and 0.858 (0.479±0.214), 0.007 and 0.848 (0.558±0.197) and0.004 and 0.865 (0.618±0.212) respectively. This research reveals that the logarithmic model yields comparatively moderate intensity-duration-frequency models that would ensure adequate sizing and forecast of relevant hydraulic structures in the study area.

Keywords: Rainfall intensity, rainfall duration, intensity - duration - frequency models, IDF