• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6B
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• pp.513-526
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• 2009

The flood control countermeasure establish for reducing of the flood damages. Design frequency usually reflects the current situation of the station, the importance and the design rainfall. Therefore, this study calculated frequency for duration maximum rainfall with the area which happened the flood damages by main heavy rainfall events recently. Also, to analyze for the temporal characteristics of rainfall event exceed by design rainfall, excess rainfall and excess frequency and excess rainfall per event calculated. To grasp the temporal variation, About excess rainfall and excess frequency and excess rainfall per event have analyzed by change and trend test. Also, rainfall observatory did grouping by cluster analysis using position of rainfall observatory and characteristic timely rainfall. For the grouping rainfall observatory by the cluster analysis calculated average of excess rainfall and excess frequency and excess rainfall per event. To compare for the temporal characteristics, the change and trend test had analyzed about excess rainfall, excess frequency by regional groups.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.5
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• pp.15-26
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• 2004

This study was conducted to derive the regional design rainfall by the regional frequency analysis based on the regionalization of the precipitation. The optimal regionalization of the precipitation data were classified by the above mentioned regionalization for all over the regions except Jeju and Ulleung islands in Korea. Design rainfalls following the consecutive duration were derived by the regional analysis using the observed and simulated data resulted from Monte Carlo techniques. Relative root mean square error (RRMSE), relative bias (RBIAS) and relative reduction (RR) in RRMSE for the design rainfall were computed and compared between the regional and at-site frequency analysis. It has shown that the regional frequency analysis procedure can substantially more reduce the RRMSE, RBIAS and RR in RRMSE than those of at-site analysis in the prediction of design rainfall. Consequently, optimal design rainfalls following the classified regions and consecutive durations were derived by the regional frequency analysis using Generalized extreme value distribution which was identified to be more optimal one than the other applied distributions. Diagrams for the design rainfall derived by the regional frequency analysis using L-moments were drawn according to the regions and consecutive durations by GIS techniques.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.5
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• pp.647-654
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• 2005

Recently, the economic losses caused by inundation are increasing due to the urbanization and industrialization, i.e., intensive land utilization and concentration of population and properties. It is regarded that the role of the storm sewer systems in urban areas becomes more important as one of the effective countermeasures for reducing the inundation losses. In this study, the effects of rainfall design frequency enhancement on the construction cost of the storm sewer systems were analyzed by increasing the design frequency from the present design frequency of the sewer systems, which is 5~10 years, to 15 years, 20 years and 30 years. The change rate functions of the design discharge and construction cost based on the various design frequencies were derived by regression analysis. According to the analysis, change the rate of design discharge at 15, 20, 30 years rainfall design frequencies were increased by 10%, 17.1%, and 27.2%, respectively, when compared to that at 10 year frequency. Furthermore, it was found that by increasing the design frequency from 10 years to 15 years, 20 years and 30 years, the construction costs were increased by 5.0%, 8.0% and 12.4%, respectively. Finally, their reliabilities need to be tested by applying the rate functions to the real storm sewer districts.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.5
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• pp.41-53
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• 2002

This study was conducted to derive the regional design rainfall by the regional frequency analysis based on the regionalization of the precipitation suggested by the first report of this project. According to the regions and consecutive durations, optimal design rainfalls were derived by the regional frequency analysis for L-moment in the second report of this project. Using the LH-moment ratios and Kolmogorov-Smirnov test, the optimal regional probability distribution was identified to be the Generalized extreme value (GEV) distribution among applied distributions. regional and at-site parameters of the GEV distribution were estimated by the linear combination of the higher probability weighted moments, LH-moment. Design rainfall using LH-moments following the consecutive duration were derived by the regional and at-site analysis using the observed and simulated data resulted from Monte Carlo techniques. Relative root-mean-square error (RRMSE), relative bias (RBIAS) and relative reduction (RR) in RRMSE for the design rainfall were computed and compared in the regional and at-site frequency analysis. Consequently, it was shown that the regional analysis can substantially more reduce the RRMSE, RBIAS and RR in RRMSE than at-site analysis in the prediction of design rainfall. Relative efficiency (RE) for an optimal order of L-moments was also computed by the methods of L, L1, L2, L3 and L4-moments for GEV distribution. It was found that the method of L-moments is more effective than the others for getting optimal design rainfall according to the regions and consecutive durations in the regional frequency analysis. Diagrams for the design rainfall derived by the regional frequency analysis using L-moments were drawn according to the regions and consecutive durations by GIS techniques.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1533-1537
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• 2005

The recent rainfall has happened to exceed the design rainfall after 1990 often, due to the characteristic of the rain to be changed. So, it is failing the ability safety of flood defense equipments to exist. This study analyzed the rainfall of Busan in 2003 since 1961 through the FARD2002(Frequency Analysis of Rainfall Duration). The result is equal to the thing which the design rainfall increased a little since 1991. The change of design rainfall created the result to be a flood discharge increase. This study investigated about the impact to influence on the river bank according to the change of flood discharge, the rainfall pattern change as well. This study used the program of HEC-RAS with HEC-HMS and calculated flood discharge with flood level of river. The result is equal to the thing which the computation became a flood level which exceed 50year(River design criteria-Korea water resources association 2002) criteria with 30year(River establishment criteria-Ministry of construction & transportation 1993), because of an area of impermeability increased of model basin.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.16-16
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• 2011

Statistics of extreme rainfall play a vital role in engineering practice from the perspective of mitigation and protection of infrastructure and human life from flooding. While flood frequency assessments, based on river flood flow data are preferred, the analysis of rainfall data is often more convenient due to the finer spatial nature of rainfall recording networks, often with longer records, and potentially more easily transferable from site to site. The rainfall frequency analysis as a design tool has developed over the years in New Zealand from Seelye's daily rainfall frequency maps in 1947 to Thompson's web based tool in 2010. This paper will present a history of the development of New Zealand rainfall frequency analysis methods, and the details of the latest method, so that comparisons may in future be made with the development of Korean methods. One of the main findings in the development of methods was new knowledge on the distribution of New Zealand rainfall extremes. The High Intensity Rainfall Design System (HIRDS.V3) method (Thompson, 2011) is based upon a regional rainfall frequency analysis with the following assumptions: $\bullet$ An "index flood" rainfall regional frequency method, using the median annual maximum rainfall as the indexing variable. $\bullet$ A regional dimensionless growth curve based on the Generalised Extreme Value (GEV), and using goodness of fit test for the GEV, Gumbel (EV1), and Generalised Logistic (GLO) distributions. $\bullet$ Mapping of median annual maximum rainfall and parameters of the regional growth curves, using thin-plate smoothing splines, a $2km\times2km$ grid, L moments statistics, 10 durations from 10 minutes to 72 hours, and a maximum Average Recurrence Interval of 100 years.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.237-240
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• 2002

Design rainfall using LH-moments following the consecutive duration were derived by the regional and at-site analysis using the observed and simulated data resulted from Monte Carlo techniques. RRMSE, RBIAS and RR in RRMSE for the design rainfall were computed and compared in the regional and at-site frequency analysis. Consequently, it was shown that the regional analysis can substantially more reduce the RRMSE, RBIAS and RR in RRMSE than at-site analysis in the prediction of design rainfall. RE for an optimal order of L-moments was also computed by the methods of L, L1, L2, L3 and L4-moments for GEV distribution. It was found that the method of L-moments is more effective than the others for getting optimal design rainfall according to the regions and consecutive durations in the regional frequency analysis. Diagrams for the design rainfall derived by the regional frequency analysis using L-moments were drawn according to the regions and consecutive durations by GIS techniques.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.5
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• pp.97-109
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• 2003

This study is mainly conducted to derive the design drought rainfall by the consecutive duration using probability weighted moments with rainfall in the regional drought frequency analysis. It is anticipated to suggest optimal design drought rainfall of hydraulic structures for the water requirement and drought frequency of occurrence for the safety of water utilization through this study. Preferentially, this study was conducted to derive the optimal regionalization of the precipitation data that can be classified by the climatologically and geographically homogeneous regions all over the regions except Cheju and Ulreung islands in Korea. Five homogeneous regions in view of topographical and climatological aspects were accomplished by K-means clustering method. Using the L-moment ratio diagram and Kolmogorov-Smirnov test, generalized extreme value distribution was confirmed as the best fitting one among applied distributions. At-site and regional parameters of the generalized extreme value distribution were estimated by the method of L-moments. Design drought rainfalls using L-moments following the consecutive duration were derived by the at-site and regional analysis using the observed and simulated data resulted from Monte Carlo techniques. Relative root-mean-square error (RRMSE), relative bias (RBIAS) and relative reduction (RR) in RRMSE for the design drought rainfall derived by at-site and regional analysis in the observed an simulated data were computed and compared. In has shown that the regional frequency analysis procedure can substantially more reduce the RRMSE. RBIAS and RR in RRMSE than those of at-site analysis in the prediction of design drought rainfall. Consequently, optimal design drought rainfalls following the regions and consecutive durations were derived by the regional frequency analysis.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.451-454
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• 2003

This study was mainly conducted to derive the design drought rainfall by the consecutive duration using probability weighted moments with rainfall in the regional drought frequency analysis. Selecting the drought rainfall series by the consecutive durations of drought observed for the long period all over the regions in Korea, optimal regionalization of the drought rainfall was classified by the climatologically and geographically homogeneous regions. Using the L-moment ratio and Kolmogorov- Smimov test, resonable frequency distribution for the drought rainfall was selected by the regions and consecutive periods of drought. Design drought rainfalls by the regions and consecutive durations were derived and compared by at-site and regional drought frequency analysis using the method of L-moments.

• Journal of Environmental Science International
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• v.29 no.9
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• pp.871-883
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• 2020

Due to recent heavy rain events, there are increasing demands for adapting infrastructure design, including drainage facilities in urban basins. Therefore, a clear definition of urban rainfall must be provided; however, currently, such a definition is unavailable. In this study, urban rainfall is defined as a rainfall event that has the potential to cause water-related disasters such as floods and landslides in urban areas. Moreover, based on design rainfall, these disasters are defined as those that causes excess design flooding due to certain rainfall events. These heavy rain scenarios require that the design of various urban rainfall facilities consider design rainfall in the target years of their life cycle, for disaster prevention. The average frequency of heavy rain in each region, inland and coastal areas, was analyzed through a frequency analysis of the highest annual rainfall in the past year. The potential change in future rainfall intensity changes the service level of the infrastructure related to hand-to-hand construction; therefore, the target year and design rainfall considering the climate change premium were presented. Finally, the change in dimensional safety according to the RCP8.5 climate change scenario was predicted.