HR: 0800h
AN: H11F-0358    [Abstracts]
TI: Development of Rainfall Time Distributions for Design Floods
AU: Yoon, Y
EM: ynyoon@korea.ac.kr
AF: Department of Civil and Environmental Engineering, College of Engineering, Korea University, Sungbuk-Ku, Seoul, 136-701 Korea, Republic of
AU: * Jang, S
EM: angel452@korea.ac.kr
AF: Department of Civil and Environmental Engineering, College of Engineering, Korea University, Sungbuk-Ku, Seoul, 136-701 Korea, Republic of
AU: Park, M
EM: watertiger@korea.ac.kr
AF: Department of Civil and Environmental Engineering, College of Engineering, Korea University, Sungbuk-Ku, Seoul, 136-701 Korea, Republic of
AU: Ahn, J
EM: wrr@skuniv.ac.kr
AF: Department of Civil Engineering, College of Engineering, Seokyung University, Sungbuk-Ku, Seoul, 136-701 Korea, Republic of
AU: Yoon, J
EM: jyyoon@korea.ac.kr
AF: Department of Environmental System Engineering, College of Science and Technology, Korea University, Seochang, Chungnam, 339-700 Korea, Republic of
AB: In the present study a new method is proposed for the determination of time distribution of design rainfall in estimating the design flood of a watershed by a rainfall-runoff model. The mean hourly rainfall data series of the watershed were first established for the whole duration of data period by averaging the concurrent rainfall data recorded at the rain gauging stations within or nearby the watershed using the Thiessen's method. Then, from the averaged rainfall data series for the watershed the rainfall amounts with a specified rainfall duration were arrayed in a descending order, resulting an annual exceedance time series. The dimensionless cumulative rainfall corresponding to each element of the exceedance series were plotted against time for specified durations. A series of representative cumulative rainfall curves were developed by assigning the probability (10% - 90%) of occurrence of each element by plotting position formula, i.e., California formula. These curves were used to select the most appropriate time distribution of design rainfall which results the maximum peak discharge by a rainfall-runoff model. The method developed were applied to actual flood events occurred in Moohan River and Chengge River basins. The shape of rainfall hyetographs showed more randomness than other empirical distributions such as Huff and Mononobe distributions. And, the design floods estimated by Clark's watershed routing method using the time distribution developed in this study were also much more closer to the observed values than using other time distributions of rainfall.
DE: 1821 Floods
DE: 1854 Precipitation (3354)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting