Development of Rainfall Intensity Duration Frequency (IDF) Curves for Hydraulic Design Aspect

Abstract

Rainfall is one of the major parts that constitute the hydrological cycle, when the rain falls on a built-up area, the water flowing over that area is known as storm water. The storm is characterized mainly by: Intensity, Duration and Frequency. Due to production of greenhouse gases, hydrologic cycle is changing day by day which is causing variations in terms of intensity, duration and frequency of rainfall events. By pinpointing the potential effects of climate change and adapting to them, is the one way to reduce regions susceptibility. Since rainfall characteristics are often used for planning and design of various water resources project, reviewing and bring up-to-date rainfall characteristics which is Intensity–Duration– Frequency (IDF) curves for future climate situations is important. The main objective of this study is to establish the empirical equations of rainfall intensity which can be used in the Upper Nyabarongo catchment (NNYU) for hydraulic structures design. It was found that intensity of rainfalls decreases with increase in rainfall duration. Further, a rainfall of any given duration will have a larger intensity if its return period is large. In other words, for a rainfall for a given duration, rainfalls of higher intensity in that duration are infrequent than rainfalls of smaller intensity.