• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.302-306
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• 2016

우리나라는 전 국토의 70%가 산지이고 하천경사가 다른 나라에 비해 상대적으로 급하여 홍수 관리에 매우 불리한 조건을 가지고 있으며, 특히 홍수기간의 집중호우 및 돌발홍수는 인명과 재산의 막대한 피해를 입히고 있다. 최근은 기후변화의 영향으로 집중호우 및 돌발홍수는 증가하는 추세에 있다. 이것은 홍수의 위험성 및 자연재해의 발생을 증대시키므로 이에 대한 하천유역 단위의 홍수량 예측 및 재해방지를 위한 설계기법의 개선과 개발, 신뢰성 있는 수문정보 획득을 위한 정밀 수문조사는 매우 필요한 상황이다. 기후변화에 대응하기 위한 수문조사의 방향은 새로운 국면에 접하였다고 볼 수 있다. 기존의 수문조사 방법을 통해 획득했던 수문량의 초과치를 벗어난 극대값의 수문량 관측 및 측정을 극복하는 문제, 홍수량 산정 및 예측을 위한 새로운 설계기법의 개발 또는 기존 방법의 개선 등 문제 해결을 위한 방향이 모색되어야 한다. 이러한 문제점을 해결하기 위해서는 중 소규모 유역 단위를 대상으로 지속적이고 신뢰성 있는 자료의 획득과 축적이 중요하나 시 공간적으로 모두 충족된 수문자료를 획득하기에는 불가능한 일이다. 따라서, 중 소규모 유역 단위의 대표성 있는 Test-bed 유역(설마천 유역/차탄천 유역)의 운영이 요구되며, 이를 통하여 얻어진 수문자료는 상기에 기술한 문제를 해결 가능하게 한다. Test-bed 유역에서 생성되는 수문자료에는 강우량, 하천수위, 지하수위 및 기상 등의 관측자료와 유량측정성과 자료가 있다. 관측된 수문자료를 이용하여 강우-유출량 분석, 증발산량 분석, 지하수함양량 분석 등 기본적인 수문특성을 분석하였다. 홍수량 예측 설계기법 개선으로는 홍수도달시간 산정방법을 검토하였으며, 최대강우강도-도달시간관계를 이용하여 도달시간을 개발하였다. 그리고 RDAPS 예측강우량과 수문모형을 이용하여 홍수량을 예측할 수 있는 시스템을 구축하였다. 유역 단위의 수문조사를 통해 생성된 수문자료는 다양한 분석과 설계에 응용되므로 지속적인 Test-bed 유역의 운영은 매우 필요한 실정이다.

• Water for future
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• v.5 no.1
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• pp.27-36
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• 1972

This thesis is the study of the rainfall probability depth in the major areas of Korea, such as Seoul, Pusan and Taegu. The purpose of the paper is to analyze the rainfall in connection with the safe planning of the hydraulic structures and with the project life. The methodology used in this paper is the statistical treatment of the rainfall data in the above three areas. The scheme of the paper is the following. 1. The complementation of the rainfall data We tried to select the maximm values among the values gained by the three methods: Fourier Series Method, Trend Diagram Method and Mean Value Method. By the selection of the maximum values we tried to complement the rainfall data lacking in order to prevent calamities. 2. The statistical treatment of the data The data are ordered by the small numbers, transformed into log, $\sqrt{}, \sqrt[3]{}, \sqrt[4], and$\sqrt[5], and calculated their statistical values through the electronic computer. 3. The examination of the distribution types and the determination of the optimum distibution types By the $x^2-Test$ the distribution types of rainfall data are examined, and rejected some part of the data in order to seek the normal rainfall distribution types. In this way, the optimum distribution types are determined. 4. The computation of rainfall probability depth in the safety project life We tried to study the interrelation between the return period and the safety project life, and to present the rainfall probability depth of the safety project life. In conclusion we set up the optimum distribution types of the rainfall depths, formulated the optimum distributions, and presented the chart of the rainfall probability depth about the factor of safety and the project life.ct life.

• Journal of Korea Water Resources Association
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• v.47 no.9
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• pp.777-787
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• 2014

Stormwater pipe systems are most commonly used to discharge rainwater from the urban catchment covered by the impervious area. To design stormwater pipe and rainwater pumping station, frequency analysis is implemented using historical rainfall and the design rainfall is timely distributed using theoretical shape such as Huff distribution. This method cannot consider the rainfall intensity variation caused by climate change which is type of uncertainty. Therefore, in this study, runoff from Gasan1 stormwater pumping stations catchment is calculated using design rainfall distributed by the 2nd quartile distribution method and the historical rainfall events. From the analysis, the nodal flooding in the urban catchment is likely caused by the high peak rainfall event rather than the large amount of rainfall. The linear regression analysis is implemented. As a result, when several storms have the same amount of rainfall, the nodal flooding in the stormwater pipe systems could be caused by the high peak of storm events. Since as the storm duration become short, the peak rainfall become high, the nodal flooding likely become severe with the short storm duration. The uncertainty in the peak data of design rainfall is analyzed and this uncertainty has to be consider in the stormwater pipe design process.

• Water for future
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• v.12 no.2
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• pp.56-62
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• 1979

Many methods of estimating design floods from rainfall data involve a trial and error procedure to determine the duration of the design rainfall, which is very complicated and time-consuming. In this study, an effort was given to derive an analytical expression for estimating the appropriate duration for use with a particular unit hydrograph. According to the so-derived analytical expression the coordinateds of hvdrograph curve and rainfall curve for the Musim Representative Basin were computed and then plotted on a same scal graph paper on which the critical durations of design rainfall excess of various recurrence intervals were determined by the point of intersection of the tow curves.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.472-476
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• 2018

비점오염물의 제거를 위해 설치하는 인공습지의 경우, 습지내로 유입되는 취입량과 배수량은 습지내로 유입되는 유입수의 체류시간을 결정하고, 습지의 침수를 방지하기위해 반드시 고려되어야 하는 사안이다. 습지의 유출입시설을 관리하고 조작하는 관리자의 입장에서 관리메뉴얼이 명확하고 직관적이지 못할 경우 강우초기에 적절히 대응하지 못해 습지의 침수 및 범람을 일으킬 수 있으며, 초기 우수 시 오염부하를 저감해야 하는 인공습지 본래의 기능을 기대하기 어렵게 된다. 그러나 각종 설계기준과 관리기준에는 이러한 사안에 대해 서언적인 관리방안만을 제시하고 있고 인공습지 설계에서도 설계서에 보편적인 내용만을 관성적으로 사용하고 있어, 영주댐 인공습지 관리메뉴얼의 사례를 소개하고자 한다. 인공습지의 설계강우량을 통해 유역의 유출유량을 산출하고, 강우별 하천수위를 산출하여 습지내 유입유량과 취수문 개도높이별 유입량 결정을 하였다. 결정된 수위별 수문개도 높이를 세부적으로 제시함으로써, 관리자는 원거리에서도 수문조작을 판단하여 대응할 수 있는 실무적인 관리방안을 제시하고자 하였다.

• Water for future
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• v.19 no.1
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• pp.75-86
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• 1986

This study aims at the analysis and application of PMP(Probable Maximum Precipitation)for the determination of design flood in the river basin planning and design of major hydraulic structures. PMP was estimated by hydro-meterological method statistical method and envelope curve method. PMF(Probable Maximum Flood)was then estimated from this PMP by synthetic unit hydrograph method and chow method. From the comparison of three methods for PMP estimation of magnitude of PMP in order of statistical, hydro-metrological, envelope curve method. Among PMP results estimated by each method it is believed that the hydro-meteorological method gave the best proper value in comparison with historical maximum rainfall because of this method reflected upon all meterological factor. From the comparison of PMP with probable rainfall and flood, it was shown that estimated value by statistical method and hydro-metrological method were nearly equivalent to the value of return period 100 years and its value of envelope curve method was equivalent to return period 200 to 500 year. It was found that PMF estimated from would be more safe for the design of major hydraulic structures in the consideration.

• Journal of Korea Water Resources Association
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• v.55 no.8
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• pp.613-621
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• 2022

Due to the global climate change, the rainfall volume and frequency on the Korean Peninsula are predicted to increase at the end of the 21st century. In addition, impervious surface areas have increased due to rapid urbanization which has caused the urban water cycle to deteriorate. Green Infrastructure (GI) researches have been conducted to improve the water cycle soundness; the efficiency of this technique has been verified through various studies. However, there are still no suitable GI design guidelines for this aspect. Therefore, the rainfall scenarios are set up for each percentile (60, 70, 80, 90) based on the volume and frequency analysis using 10-year rainfall data (Busan Meteorological Station). After determining the GI areas for each scenario, the runoff reduction characteristics are analyzed based on Storm Water Management Model (SWMM) 10-year rainfall-runoff-simulations. The total runoff reduction efficiency for each GI areas are computed to have a range of 13.1~52.1%. As a results of the quantitative analysis, the design rainfall for GI is classified into the 80~85 percentile in the study site.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.571-577
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• 2005

최근 일련의 기상이변현상은 과거의 기상현상과 달리 국지성 호우 발생과 강우량의 증가현상으로 나타나고 있으며, 이러한 집중호우로 인해 발생하는 홍수규모는 기존의 수공구조물들을 위협할 수준에까지 이르러 기존 수공구조물의 안전성에 대한 재검토 필요성과 신규 구조물에 대한 안전성 확보대책이 강구되고 있다. 이에 따라 수문관련의 실무에서는 설계홍수량의 산정시 설계강우에 대한 임계지속기간의 개념이 적용되고 있으나, 아직까지 설계지침에는 이에 대한 명확한 기준이 구체적으로 제시되어 있지 못한 실정이다. 따라서 본 연구에서는 수공구조물의 설계에 필요한 임계지속기간의 결정에 도움을 주고자 설계홍수량 산정시 설계 강우로부터 홍수량을 산정하기 위한 일련의 과정에서 이용되는 유역 및 기상 특성인자 등의 제반 수문요소에 따른 임계지속기간의 변동양상을 파악하고, 임계지속기간과 재현기간, 유역특성인자, 단위도 단위시간과의 관계 및 임계지속기간에 대한 강우지속기간과 첨두홍수량의 변화 등을 분석하여 설계강우의 임계지속기간 산정을 위한 기초연구자료를 제시하고자 하였다.

• Journal of Korea Water Resources Association
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• v.33 no.2
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• pp.263-276
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• 2000

This paper is to derive the probable rainfall depths and the probable rainfall intensity formulas for Inchon Metropolitan district. The annual maximum rainfall data from 10 min. to 6 hours have been collected from the Inchon weather station. Eleven types of probability distribution are considered to estimate probable rainfall depths for 12 different storm durations at the Inchon Metropolitan district. Three tests including Chi-square, Kolmogorov-Smimov and Cramer Von Mises with the graphical analysis are adopted to select the best probability distribution. The probable rainfall intensity formulas are then determined by the least squares method using the trial and error approach. Five types of Talbot type, Sherman type, Japanese type, Unified type I, and Unified type II are considered to determine the best type for the Inchon rainfall intensity. The root mean squared errors are computed to compare the accuracy from the derived formulas. It has been suggested that the probable rainfall intensities having Unified type I for the short term duration should be the most reliable formulas by considering the root mean squared errors and the difference between computed probable rainfall depth and estimated probable rainfall depth.

• Journal of Korea Water Resources Association
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• v.52 no.12
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• pp.963-973
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• 2019

This study reviews a urban flooding risk criteria estimation model to predict risk criteria in areas where flood risk criteria are not precalculated by using watershed characteristic data and limit rainfall based on damage history. The risk criteria estimation model was designed using Support Vector Machine, one of the machine learning algorithms. The learning data consisted of regional limit rainfall and watershed characteristic. The learning data were applied to the SVM algorithm after normalization. We calculated the mean absolute error and standard deviation using Leave-One-Out and K-fold cross-validation algorithms and evaluated the performance of the model. In Leave-One-Out, models with small standard deviation were selected as the optimal model, and models with less folds were selected in the K-fold. The average accuracy of the selected models by rainfall duration is over 80%, suggesting that SVM can be used to estimate flooding risk criteria.