• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.2
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• pp.108-122
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• 1996

This study was to introduced estimation model for optimum probabilistic rainfall intensity on hydrological area. Originally, probabilistic rainfall intensity formula have been characterized different coefficient of formula and model following watersheds. But recently in korea rainfall intensity formula does not use unionize applyment standard between administration and district. And mingle use planning formula with not assumption model. Following the number of year hydrological duration adjust areal index. But, with adjusting formula applyment was without systematic conduct. This study perceive the point as following : 1) Use method of excess probability of Iwai to calculate survey rainfall intensity value. 2) And, use method of least squares to calculate areal coefficient for a unit of 157 rain gauge station. And, use areal coefficient was introduced new probabilistic rainfall intensity formula for each rain gauge station. 3) And, use new probabilistic rainfall intensity formula to adjust a unit of fourteen duration-a unit of fifteen year probabilistic rainfall intensity. 4) The above survey value compared with adjustment value. And use three theory of error(absolute mean error, squares mean error, relative error ratio) to choice optimum probabilistic rainfall intensity formula for a unit of 157 rain gauge station.

• Journal of Wetlands Research
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• v.2 no.1
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• pp.49-58
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• 2000

The frequency analysis of annual maximum rainfall data and the derivation of probable rainfall intensity formula at Masan station are performed in this study. Based on the eight different rainfall duration data from 10 minutes to 24 hours, eight types of probability distribution (Gamma, Lognormal, Log-Pearson type III, GEV, Gumbel, Log-Gumbel, Weibull, and Wakeby distributions), three types of parameter estimation scheme (moment, maximum likelihood and probability weighted methods) and three types of goodness-of-fit test (${\chi}^2$, Kolmogorov-Smirnov and Cramer von Mises tests) were considered to find an appropriate probability distribution at Masan station. The Lognormal-2 distribution was selected and the probable rainfall intensity formula was derived by regression analysis. The derived formula can be used for estimating rainfall quantiles of the Masan vicinity areas with convenience and reliability in practice.

• Journal of Environmental Science International
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• v.23 no.11
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• pp.1775-1790
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• 2014

The regional rainfall intensity formula for Gimhae in Gyeongsangnam-do province is developed in this study. The nine points of rainfall observations were selected. In order to demonstrate the accuracy and the versatility of the proposed rainfall intensity formula, three regions under the jurisdiction of the Meteorological Agency near Gimhae, namely Busan, Changwon, Miryang observatories were selected. The present formula can be effectively employed for various design of hydraulic structures in Gimhae area since it is divided into several refined regions.

• Journal of the Korean Society of Hazard Mitigation
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• v.1 no.1 s.1
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• pp.103-115
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• 2001

The current procedure to design hydraulic structures in a small basin area is to estimate the probable rainfall depth using rainfall intensity formula. The estimation of probable rainfall depth has many uncertainties inherent with it. However, it has been inevitable to simplify the nonlinearity if the rainfall in practice. This study attend to address a method which can model the nonlinearity in order to derive better rainfall intensity formula for the estimation of probable rainfall depth. The results show that genetic algorithm is more reliable and accurate than trial-and-error method or nonlinear programming technique(Powell's method) in the derivation of the rainfall intensity formula.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4
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• pp.135-143
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• 1992

The probable rainfall depth is an important hydrologic design data in establishing the hydraulic engineering project at urban watershed. This study is to unificate the probable rainfall intensity formula at Seoul. The probable rainfall intensity formula at Seoul is basically formed by the types of Talbot, Sherman and Japanese. But these formulae may be unified to uniform type. The unified probable rainfall intensity formula is more applicable than that of the existing types at Seoul. Especially on the probable rainfall depth of total duration the application of unified formula general type is better than existing types. In this formula, values of n are decreasing with return period and increasing with rainfall duration, and values of coefficient, b, are decreasing with the increase of return period. The range of n varies from 0.55 to 0.60 for short duration, from 0.60 to 0.82 for long duration, and from 0.60 to 0.66 for total duration of probable rainfall depth.

• Journal of Korea Water Resources Association
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• v.41 no.6
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• pp.587-595
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• 2008

In order to aid the derivation of the IDF relationship for a station with insufficient duration-rainfall data, an approach to derive a simple and practical IDF formula is presented. The IDF formula is described simply by the term of the two parameters and a design frequency. The model parameters were estimated from a statistical technique based on the normal distribution of transformed rainfall intensities. In order to give the transformed data, both the Kruskal-Wallis statistic and the Manly transformation of duration-rainfall data were adopted. With the methods, the proposed IDF formula becomes a simpler model that compares well with conventional form. In addition, it allows avoiding an exceptional condition of the higher rainfall intensity for longer duration. The performance of the proposed formula was evaluated by using the limited rainfall data for short duration from two gauge stations. The result showed that the IDF formula developed in this work was an effective tool, providing a reliable relationship between the intensity and duration even though insufficient data are only available.

• Journal of Korea Water Resources Association
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• v.53 no.4
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• pp.237-247
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• 2020

The purpose of this study is to analyze whether design rainfall and hyetograph, which are the main elements of design rainfall, can properly reflect the those of observed rainfalls through inundated rainfall events. The target areas were selected at seven large cities with high damages regarding to the flooding. Comparative analysis between probability and observed rainfall shows that 57% of the cases, in which rainfall amount through the IDF curve is estimated lower than the observed rainfall, do not properly reflect the observed rainfalls. In particular, this trend is exacerbated by the cases in low return period and the rain type of typhoon or frontal rain. The comparative results of rainfall intensity formula showed that the Talbot and Japanese formula were stable in the short- and long-term return periods, respectively. The comparison of hyetograph results also showed that the Mononobe method properly reflects the maximum rainfall intensity and the Huff method properly reflects the shape of rainfall pattern.

• Korean Journal of Agricultural Science
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• v.8 no.1
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• pp.82-89
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• 1981

The characteristic of rainfall intensity in short duration is very important to calculate short-term runoff in small watershed by Rational method. Therefore, the purpose of this study is to derive the most proper formula on the probable rainfall intensity in each return period in Daejeon area. And the results of this study could be utilized for the design of drainage-structures in small watershed, drainage system in urban area and flood control in small river basin. The result s of this study are summerized as follows. 1. Gumbel-Chow method which shows the mean value was chosen to calculate the probable rainfall in tensity in each return periods. 2. According to statistical judgement, probable rainfall intensity formula of Japanese type($I={\frac{a}{t+b}}$, see Table-6) shows the most proper one among other types of formula like Talbot type, Sherman type and Characteristic coefficient method. Probable rainfall in tensity value of Japanese type in Daejeon area shows well coincidence with the one obtained by applying prof. Park's n-coefficient to Monobe formula $I=({\frac{R_{24}}{24}})({\frac{T}{t}})^{0.5486}$. On the other hand, the value by Monobe formula with n-coefficient of 2/3 which is being used as a disign criterison by M. O. C. shows large difference from the fore-mentioned results (see Table-7). Consequently the value by Monobe formula might be judged that it is too much overestimated one as a design criterion. 3. Short-term runoff in small water shed could be calculated more reasonably in Daejeon area through this probable rainfall in tensity formula.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.1
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• pp.115-120
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• 1993

The study is to derive a typical probable rainfall intensity formula(TPRIF) by analyzing pre-issued probable rainfall intensity formulas (PPRIF) over principal rainfall observation stations, and to obtain the regional characteristics based on the rainfall patterns by evaluating probable rainfall amount. The conclusions are as follows. A TPRIF which integrates PPRIF with a single pattern is presented. In deriving probable rainfall intensity, the application of TPRIF was more excellent than that of PPRIF. The value of R24/Rl which is the dimensionless ratio for rainfall characteristics tends to be inversely proportionate to the regional coefficient n. By comparing these values, the whole country could be divided into about 5 regions. In these five regions, the short-duration rainfall intensity is dominant in inland areas but the long-duration rainfall intensity is dominant in East Sea areas.

• Journal of Korea Water Resources Association
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• v.39 no.6 s.167
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• pp.521-531
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• 2006

The formula was proposed through the examination of probability rainfall intensity formula used in Incheon based upon recent occurrences of heavy rain and extraordinary storms. Random-time maximum annual rainfalls were estimated for durations from ten minutes to twenty-four hours from the data by Korea Meteorological Administration. Eleven types of probability distribution are considered to estimate probable rainfall depths for different storm durations at Incheon city. Three goodness-of-fit tests including Chi-square, Kolmogorov-Smirmov and framer Von Misses were used to analyze the tendency of recent rainfall. Considering maximum rainfall occurred, General Extreme Value(GEV) distribution was chosen as the appropriate probability distribution. Five types of probability rainfall formulas including Talbot type, Sherman type, Japanese type, unified type I and unified type II are considered to determine the best type for rainfall intensity at Incheon. The formula was determined considering the time of concentration of sewer system and river at Incheon city. Unified type I was chosen for its accuracy and was proposed to represent rainfall intensity of Incheon district.