Study on Singapore’s rainfall intensity-duration-frequency (IDF) relationships

Intensity–duration–frequency (IDF) curve is one of the most commonly used tools in the design of storm management systems. It is use to anticipate rainfall event by interpreting past rainfall records to determine a pattern and determine the likelihood of any future rainfall events. Wit this data it possible for appropriate sizing for the storm management systems. Without the IDF curve, storm system may be undersized, resulting in floods or oversized resulting in significant economic loss due to loses of land or increase in capital cost to build an oversized system. The two most common frequency analysis methods deployed to generate such a curve is the log-Pearson type III (LPIII) and the Gumbel extreme value type I. Both methods have been used in different countries though only one of these is usually officially adopted for a specific country. For example, Singapore utilizes the Gumbel distribution while the United States utilizes the LPIII. Furthermore, aside from the frequency analysis method, there are also different ways these methods can be deployed to generate the IDF curve. Examples include having a regional or state-specific IDF curve or updates to account for the effects of climate change This report aims to analyze Singapore’s rainfall records and assess if there is a reasonable need to alter the current method used for developing the IDF curve.Bachelor of Engineering (Environmental Engineering