Kurian, V. J. and Febik, J. K. and Nurmin Bolong and Ishak Zakaria
(2007)
*Isopleths for rainfall data in Sabah.*
In: World Environmental and Water Resources Congress 2006: Examining the Confluence of Environmental and Water Concerns, 21-25 May 2006, Omaha, Ne..

## Abstract

Isopleths are lines along which rainfalls have the same specified intensity. These isopleths form the basic information needed for the design of systems needed for roof drainage, urban drainage, water supply, irrigation and flood control. Hence they are very important for 'water management'. For the design of roof drainage systems, rainfall data for short durations such as 2 minutes, 5 minutes, 10 minutes & 15 minutes are needed for return periods of 50 and 100 years. In Sabah State of Malaysia (Part of Borneo Island), from 1960 to 1984, only few stations were recording rainfall and that too only daily rainfalls. So, the minimum duration data available was only for 1 day. From 1985 onwards, the data for 5 minutes, 15 minutes, 30 minutes, 60 minutes & 120 minutes have been recorded along with daily rainfall. The available rainfall data is only for 19 years from 1985 to 2003. Based on these available data, rainfall data for longer return periods such as upto 100 years are predicted using multiple regression analysis of exponential type. The equation used is P=KT at bT 1cP 1d where P is the rainfall in mm, T is the return period of P in years, t is the duration of P in minutes, T 1 is the return period of P 1 in years, P 1 is the daily rainfall in mm and K, a, b, c, d are constants. After completing the Intensity -Duration -Frequency (IDF) curves for 52 stations & using these data, isopleths for storms of duration 5 minutes for return periods of 20 years, 50 years & 100 years are plotted. Using these isopleths, it would be possible to estimate the design rainfall for any location in Sabah.

Item Type: | Conference or Workshop Item (UNSPECIFIED) |
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Keyword: | Floods, Information systems, Rainfall, Daily rainfall, Exponential type, Malaysia, Multiple regression analysis, Rainfall data, Return periods, Roof drainage systems, Short durations, Urban drainage, Design, Flood control, Floods, Information systems, Regression analysis, Roofs, Water management, Water supply, Rain |

Subjects: | Q Science > QC Physics > QC1-999 Physics > QC851-999 Meteorology. Climatology Including the earth's atmosphere |

Department: | SCHOOL > School of Engineering and Information Technology |

Depositing User: | ADMIN ADMIN |

Date Deposited: | 19 Mar 2012 10:15 |

Last Modified: | 29 Dec 2014 16:40 |

URI: | https://eprints.ums.edu.my/id/eprint/3726 |

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