• Title/Summary/Keyword: POT 계열

Search Result 16, Processing Time 0.028 seconds

Frequency Analysis of Partial Duration Series for Flood Discharge of Rivers (하천 홍수량에 대한 부분시계열 빈도분석)

  • Lee, Gyu-Min;Jun, Kyung-Soo
    • Proceedings of the Korea Water Resources Association Conference
    • /
    • 2010.05a
    • /
    • pp.174-178
    • /
    • 2010
  • 일반적으로 설계홍수량은 강우빈도 해석으로 설계강우량을 결정하고 이를 유역유출모형에 적용하여 계산된 유출량을 정상류모의를 통하여 산정하게 된다. 이러한 기존의 설계홍수량 산정방법은 설계강우량 산정에 있어 임의성을 포함하게 된다. 따라서 본 연구에서는 대상 하천 구간의 실측 수위자료를 사용하여 홍수량을 산정하는 방법을 제시하고자 한다. 분석대상 자료로서 남한강 여주지점의 실측 시유량을 선정하였으며 충주댐 완공 이후인 1988년부터 2007년까지의 기간을 대상으로 하였다. 빈도해석을 위한 분석 자료군을 연최대치 계열과 POT(Peaks Over Threshold) 계열의 두 가지 그룹으로 추출하여 홍수량을 추정하였다. 연최대치 계열 분석 결과 Weibull 분포를 적절한 분포형으로 선정하였으며 부분시계열 POT 빈도해석을 수집자료 전체와 기간을 전, 후 10년씩 나눈 세 그룹으로 나누어 수행하였다. 빈도별 확률홍수량 추정 결과 연최대치 계열을 사용한 결과가 부분시계열 POT 방법을 사용한 결과보다 크게 산정되었으며 자료 전체 기간에 대한 POT 빈도해석 결과보다 최근 10년간의 자료를 사용한 결과가 더 크게 나타나 홍수량의 증가 경향을 확인 할 수 있었다.

  • PDF

Appropriate Sample Size for Bivariate Frequency Analysis of Rainfall Event using Peaks Over Threshold (POT) (강우사상 이변량 빈도해석을 위한 Peaks Over Threshold (POT) 방법을 이용한 적정 확률표본 선택 연구)

  • Joo, Kyungwon;Kim, Hanbeen;Ahn, Hyunjun;Heo, Jun-Haeng
    • Proceedings of the Korea Water Resources Association Conference
    • /
    • 2018.05a
    • /
    • pp.304-304
    • /
    • 2018
  • 이변량 빈도해석은 일반적으로 고정지속기간 강우량에 대해 빈도해석하는 단변량 빈도해석에 비해 지속기간을 확률변수로 이용하여 강우량과 동시에 확률변수로 사용할 수 있다는 장점이 있다. 하지만 확률분포형의 차원이 증가하기 때문에 기존 단변량 빈도해석에서 요구되던 표본크기보다 더 많은 표본이 필요하다. 우리나라 강우관측소의 경우 오래된 관측소의 경우에도 기록년수가 60년을 넘지 않아 연최대계열로 확률표본을 작성할 경우 이변량 빈도해석을 수행하기에 부족할 수 있다. 따라서 본 연구에서는 Peaks Over Threshold (POT) 방법을 이용하여 적정 확률표본을 선택하는 연구를 진행하였다. 서울 기상청 지점의 강우자료로부터 최소무강우시간을 이용하여 모든 강우사상을 추출하였으며 각 강우사상의 강우량과 지속기간이 확률변수로 사용되었다. 기존에 알려진 POT 방법들과 Anderson-Darling 적합도 검정을 이용한 절단값 산정방법등을 적용하여 확률표본 개수의 변화에 따른 주변분포형의 적합도 검정과 이변량 확률모형의 적합성을 살펴보았다.

  • PDF

Concept of Seasonality Analysis of Hydrologic Extreme Variables and Design Rainfall Estimation Using Nonstationary Frequency Analysis (극치수문자료의 계절성 분석 개념 및 비정상성 빈도해석을 이용한 확률강수량 해석)

  • Lee, Jeong-Ju;Kwon, Hyun-Han;Hwang, Kyu-Nam
    • Journal of Korea Water Resources Association
    • /
    • v.43 no.8
    • /
    • pp.733-745
    • /
    • 2010
  • Seasonality of hydrologic extreme variable is a significant element from a water resources managemental point of view. It is closely related with various fields such as dam operation, flood control, irrigation water management, and so on. Hydrological frequency analysis conjunction with partial duration series rather than block maxima, offers benefits that include data expansion, analysis of seasonality and occurrence. In this study, nonstationary frequency analysis based on the Bayesian model has been suggested which effectively linked with advantage of POT (peaks over threshold) analysis that contains seasonality information. A selected threshold that the value of upper 98% among the 24 hours duration rainfall was applied to extract POT series at Seoul station, and goodness-fit-test of selected GEV distribution has been examined through graphical representation. Seasonal variation of location and scale parameter ($\mu$ and $\sigma$) of GEV distribution were represented by Fourier series, and the posterior distributions were estimated by Bayesian Markov Chain Monte Carlo simulation. The design rainfall estimated by GEV quantile function and derived posterior distribution for the Fourier coefficients, were illustrated with a wide range of return periods. The nonstationary frequency analysis considering seasonality can reasonably reproduce underlying extreme distribution and simultaneously provide a full annual cycle of the design rainfall as well.

A Study on Optimal Time Distribution of Extreme Rainfall Using Minutely Rainfall Data: A Case Study of Seoul (분단위 강우자료를 이용한 극치강우의 최적 시간분포 연구: 서울지점을 중심으로)

  • Yoon, Sun-Kwon;Kim, Jong-Suk;Moon, Young-Il
    • Journal of Korea Water Resources Association
    • /
    • v.45 no.3
    • /
    • pp.275-290
    • /
    • 2012
  • In this study, we have developed an optimal time distribution model through extraction of peaks over threshold (POT) series. The median values for annual maximum rainfall dataset, which are obtained from the magnetic recording (MMR) and the automatic weather system(AWS) data at Seoul meteorological observatory, were used as the POT criteria. We also suggested the improved methodology for the time distribution of extreme rainfall compared to Huff method, which is widely used for time distributions of design rainfall. The Huff method did not consider changing in the shape of time distribution for each rainfall durations and rainfall criteria as total amount of rainfall for each rainfall events. This study have suggested an extracting methodology for rainfall events in each quartile based on interquartile range (IQR) matrix and selection for the mode quartile storm to determine the ranking cosidering weighting factors on minutely observation data. Finally, the optimal time distribution model in each rainfall duration was derived considering both data size and characteristics of distribution using kernel density function in extracted dimensionless unit rainfall hyetograph.

The Statistical Model for Predicting Flood Frequency (홍수 빈도 예측을 위한 통계학적 모형)

  • 노재식;이길춘
    • Water for future
    • /
    • v.25 no.2
    • /
    • pp.89-97
    • /
    • 1992
  • This study is to verify the applicability of statistical models for predicting flood frequency at the stage gaging stations selected by considering whether the flow is natural condition in the Han River basin. From the result of verification, this statistical flood frequency models showed that is fairly reasonable to apply in practice, and also were compared with sampling variance to calibrate the statistical dfficiency of the estimate of the T year flood Q(T) by two different flood frequency models. As a result, it was showed that for return periods greater than about T=10 years the annual exceedence series estimate of Q(T) has smaller sampling variance than the annual maximum series estimate. It was showed that for the range of return periods the partial duration series estimate of Q(T) has smaller sampling varianed than the annual maximum series estimate only if the POT model contains at least 2N(N:record length)items or more in order to estimate Q(T) more efficiently than the ANNMAX model.

  • PDF

Regional Frequency Analysis for a Development of Regionalized Regression Model of River Floods (하천홍수량의 지역화 회귀모형개발을 위한 지역빈도해석)

  • Noh, Jae Sik;Lee, Kil Choon
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.13 no.3
    • /
    • pp.139-154
    • /
    • 1993
  • The major purpose of this study is to develop a regionalized regression model, which predicts flood peaks from the characteristics of the ungaged catchments, through the regional flood frequency analysis for the selected stage gauging stations located on several natural rivers of Korea. The magnitude and the frequency of flood peaks with specified recurrence intervals were estimated from the flood frequency analysis on the 28 selected stage gauging stations distributed on the five major rivers of Korea. The results of the analysis were compared with the predictions from the two different flood frequency models. From the statistical evaluation of these models, it was revealed that the POT model (Peaks Over a Threshold model), which is based on the partial duration method, is more effective in predicting flood peaks from short period records than the ANNMAX model (ANNual MAXimum model) which is based on the annual maximum series method. A regionalized regression model was developed to facilitate the estimation of design floods for ungaged catchments through the regression analysis between flood peaks and the topographic characteristics of the catchments assumed to be important in runoff processes. In addition to this, the correlation diagrams are presented which show the relationships between flood peaks with specified recurrence intervals and the major characteristics of the catchments.

  • PDF

Concept of Seasonality Analysis of Hydrologic Extreme Variables and Effective Design Rainfall Estimation Using Nonstationary Frequency Analysis (극치수문자료의 계절성 분석 개념 및 비정상성 빈도해석을 이용한 유효확률강수량 해석)

  • Kwon, Hyun-Han;Lee, Jeong-Ju;Lee, Dong-Ryul
    • Proceedings of the Korea Water Resources Association Conference
    • /
    • 2010.05a
    • /
    • pp.1434-1438
    • /
    • 2010
  • 수문자료의 계절성은 수자원관리의 관점에서 매우 중요한 요소로서 계절성의 변동은 댐의 운영, 홍수조절, 관계용수 관리 등 다양한 분야와 밀접한 관계를 가지고 있다. 그러나 지금까지의 수문 자료의 계절성 평가는 주로 이수과점에서 이루어지고 있으며 치수관점에서 극치수문량의 계절성을 평가하는 연구는 미진한 실정이다. 이는 극치수문량을 해석하는 방법론으로서 연최대치계열(annual maxima) 즉, Block Maxima가 이용됨에 따라 나타나는 문제점이다. 그러나 부분기간치계열(partial duration series)을 활용하게 되면 자료의 확충뿐만 아니라 자연적으로 극치수문량의 계절성에 대한 평가 또한 가능하다. 이러한 분석과정을 POT(peak over threshold)분석이라 하며 일정 기준값(threshold) 이상의 자료를 모두 취하여 빈도해석에 이용하는 방법으로서 기존 방법의 경우 연최대값이 일반적으로 7월과 8월에만 존재하게 되지만 POT 분석의 경우 여러 달에 걸쳐 빈도해석을 위한 자료가 구성되게 된다. 이를 빈도해석으로 연계시키기 위해서는 계절성을 비정상성으로 고려하여 모형화 할 수 있는 방법론의 개발이 필요하다. 본 연구에서는 이러한 목적을 위해서 계절성을 고려할 수 있는 비정상성빈도해석 기법의 개념을 제시하고 모형으로 개발하고자 한다. GEV 또는 Gumbel 분포의 매개변수와 계절성을 연계시키기 위해서 Fourier 급수가 활용되며 매개변수는 Bayesian 기법을 통해 최적화 된다. 이를 통하여 설계강수량의 계절적 분포를 정량적으로 해석할 수 있으며 미래의 극치강수량에 대한 분포특성 또한 확률적으로 해석이 가능하다. 본 연구에서 제안된 방법은 국내외 시간강수량자료에 적용되어 적합성과 적용성이 평가된다.

  • PDF

Selection of Korean Native Plants as Outdoor Pot Plants (실외 화분용 자생식물 선발)

  • Sohn, Kwanhwa;Kim, Hoon Sik
    • FLOWER RESEARCH JOURNAL
    • /
    • v.18 no.2
    • /
    • pp.98-109
    • /
    • 2010
  • 78 Korean native plants, which have not been used in general, were selected to be used as outdoor pot plants for three seasons, from spring to autumn. Plants, which were explored in about 30 places of Korea from 2007 to 2009, were transplanted to or sown in white plastic general pots ($27.5cm({\Phi}){\times}27.5cm(H)$) and hanging pots($28cm({\Phi}){\times}13cm(H)$) and grown in the garden of 36''56' latitude(N) and 127''09' longitude(E). 38 species(13 families and 29 genus) were suitable for outdoor general pots, and 46 species(28 families and 43 genus) for outdoor hanging pots. Among 38 plants for outdoor general pots, the principal species, which were easy to grow and have not been used in general, were 16 species, Metaplexis japonica in Asclepiadaceae, Phyteuma japonicum in Campanulaceae, Artemisia capillaris, Artemisia princeps, and Artemisia selengensis in Compositae, Carex humilis in Cyperaceae, Pennisetum alopecuroides, and Setaria viridis in Gramineae, Agastache rugosa, Glechoma hederacea, Elsholtzia splendens, Isodon inflexus, and Mosla punctulata in Labiatae, Vicia villosa in Leguminosae, Piper kadzura in Piperaceae, and Rosa multiflora var. multiflora in Rosaceae. Among 46 plants for outdoor hanging pots, the principal species, which were easy to grow and have not been used in general, were 17 species, Metaplexis japonica in Asclepiadaceae, Ixeris stonlonifera in Compositae, Calystegia japonica and Quamoclit angulata in Convolvulaceae, Dioscorea batatas in Dioscoreaceae, Glechoma hederacea and Thymus quinquecostatus in Labiatae, Trifolium lupinaster for. alpinus and Vicia villosa in Leguminosae, Menispermum dauricum in Menispermaceae, Piper kadzura in Piperaceae, Clematis mandshurica for. lancifolia in Ranunculoideae, Rosa multiflora var. multiflora and Potentilla fragarioides var. major in Rosaceae, Paederia scandens and Rubia akane in Rubiaceae, and Parthenocissus tricuspidata in Vitaceae.

New Yellow Single Chrysanthemum 'My Sun' for Pot Plant (분화용 국화 노랑색 홑꽃 'My Sun' 육성)

  • Jung, Yun-Kyung;Lim, Jae-Wook;Lee, Sang-Deok
    • Horticultural Science & Technology
    • /
    • v.30 no.3
    • /
    • pp.325-328
    • /
    • 2012
  • A new Dendranthema grandiflourm 'My Sun' was developed at Gyeonggi-do Agricultural Research & Extension Services (GARES), Korea in 2009. 'My Sun' was initially derived from the cross in 2005 between 'Omega Time Orange', a potted chrysanthemum cultivar with orange single type, and 'Tasman', a potted chrysanthemum cultivar with white single type in 2005. The cultivar has single type flowers with yellow petals. Trial and evaluation was conducted from 2006 to 2009 for the selection of this variety, including a shading culture in spring and a retarding culture in winter. The flowering time of 'My Sun' was October 13th, and year-round flowering is possible by shading or lighting treatment. The diameter of flower is 21.0 mm. Numbers of flowers per stem and petals per flower are 34.4 and 20.4, respectively. Its leaf color was green (Green Group 137A) and plant height was 13.3 cm. Days to flowering under the short day treatment is about 42 in spring, and numbers of branch per plant was 3.4 ea in the winter. This cultivar was resistance to white rust and consumer's preference of new pot-mum is high level than control.

Estimation of Deepwater Design Wave Height on Southern Coast of Korean Peninsula by Empirical Simulation Technique (경험모의기법에 의한 남해안의 심해 설계파고 산정)

  • Suh, Kyung-Duck;Kim, Mun-Ki;Chun, Je-Ho
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.23 no.4
    • /
    • pp.265-275
    • /
    • 2011
  • Estimation of wave height is the most important factor in the design of coastal structures such as breakwaters. In the present study, typhoon wind distribution was constructed by applying the parametric model of Holland (1980), and numerical simulations on the typhoon-generated waves were carried out using the WAM. The typhoons which affected the southern coast of the Korean Peninsula and several hypothetical typhoons were selected to construct the training sets. Design wave heights were estimated using the empirical simulation technique for various return periods and wave directions. The estimated design wave heights were compared with those by the peaks-over-threshold method and the results of KORDI(2005).