• Proceedings of the Korea Water Resources Association Conference
• /
• 2007.05a
• /
• pp.209-213
• /
• 2007

최근 우리나라에서는 기상이변과 기후변화에 의한 국지성 집중호우의 발생으로 인해 인명 및 재산 피해가 증가하고 있고, 특히 도시지역의 경우 산업화와 도시화로 인한 홍수량 및 첨두홍수량이 뚜렷하게 증가하고 있는 것으로 나타나고 있다. 이에 따라 기후변화와 도시화 등을 고려한 확률수문량의 재산정이 요구되고 있으며, 이를 위한 한 방법으로 지역빈도해석(regional frequency analysis)에 대한 연구가 꾸준히 진행되고 있으나 도시유역에 대한 지역빈도해석에 관한 연구는 미비한 실정이다. 따라서 본 연구에서는 도시지역에 대한 지역빈도해석의 적용성을 검토하기 위해 주요 도시유역을 분석대상으로 선정하고, 해당 도시유역 내의 AWS(Automatic Weather System) 자료를 수집한다. 대상지역의 AWS 자료를 구축한 후, 각각의 자료에 대해 대표적인 지역빈도해석 기법 중의 하나인 홍수지수법(Index Flood Method)을 적용하여 확률강우량을 산정하고 지점빈도해석 결과와 비교하여 도시유역에 대한 지역빈도해석의 적용성을 판단하고자 한다. 대상지역에 대한 홍수지수법의 적용결과를 살펴보면, 지점빈도해석에 의한 확률강우량보다 홍수지수법에 의해 산정된 확률강우량이 작게 추정되는 것으로 나타났다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2017.05a
• /
• pp.80-80
• /
• 2017

최근 수문자료에 비정상성이 관측됨에 따라 비정상성 지역빈도해석에 대한 연구가 진행되고 있다. 홍수지수법 (index flood method)은 지역빈도해석에서 가장 널리 사용되는 방법으로 각 지점의 특성을 반영하는 홍수지수 (index flood)와 지역적 특성을 대표하는 성장곡선 (growth curve)을 통해 확률수문량을 산정하며, 비정상성 지역빈도해석의 경우 홍수지수법 내의 요소들을 시간에 대한 함수로 정의함으로써 비정상성을 반영한다. 본 연구에서는 다양한 형태의 비정상성 홍수지수법을 통해 비정상성 지역빈도해석을 수행하고 각 방법에 따른 성능을 비교하였다. 이를 위해 경향성을 가지는 매개변수를 포함하는 비정상성 분포형을 모분포로 가지는 자료를 생성하였으며, 이를 기반으로 다양한 경향성을 가지는 자료들로 지역을 구성하였다. 구성된 지역에 대해 동질성 검토를 수행하여 비정상성 자료들이 포함된 지역의 동질성을 확인하였으며, Monte Carlo 모의실험을 통해 각 비정상성 홍수지수모형에 대한 확률수문량의 RRMSE와 RBIAS를 산정하여 성능을 평가하였다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2018.05a
• /
• pp.299-299
• /
• 2018

지역빈도해석은 수문관측자료의 보유기간이 짧은 지점 또는 미계측 지점에 대하여 보다 정확하며 신뢰할 수 있는 설계수문량을 산정하기 위해 널리 사용되고 있는 방법이다. 지역빈도해석에서 사용되는 가장 대표적인 모형인 홍수지수모형 (index flood model)은 각 지점의 표본평균을 홍수지수로 정의하고 이를 이용하여 설계수문량을 산정하는 방법이다. 모홍수지수모형 (population index flood model)은 표본평균을 홍수지수로 사용함으로써 발생하는 설계수문량의 왜곡과 오차를 극복하기 위해 제안된 방법으로 홍수지수를 미지의 모분포로 가정한 후 설계수문량을 산정한다. 본 연구에서는 모홍수지수모형을 국내 강우관측자료에 적용하여 지역빈도해석을 수행하고자 한다. 먼저, 이질성척도(heterogeneity)를 통해 지역동질성이 확인된 지역에 대하여 GEV 분포형을 적용한 비정상성 모홍수지수모형을 적용해 지역빈도해석을 수행하고 확률강우량을 산정하였다. 또한, 기존의 지점빈도해석 및 L-moment 기반의 지역빈도해석 결과와 비교를 통해 모홍수지수모형의 적용성을 확인하였다.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.45 no.1
• /
• pp.33-44
• /
• 2003

This study was conducted to estimate the design flood by the determination of best fitting order for LH-moments of the annual maximum series at fifteen watersheds. Using the LH-moment ratios and Kolmogorov-Smirnov test, the optimal regional probability distribution was identified to be the Generalized Extreme Value (GEV) in the first report of this project. Parameters of GEV distribution and flood flows of return period n years were derived by the methods of L, L1, L2, L3 and L4-moments. Frequency analysis of flood flow data generated by Monte Carlo simulation was performed by the methods of L, L1, L2, L3 and L4-moments using GEV distribution. Relative Root Mean Square Error. (RRMSE), Relative Bias (RBIAS) and Relative Efficiency (RE.) using methods of L, Ll , L2, L3 and L4-moments for GEV distribution were computed and compared with those resulting from Monte Carlo simulation. At almost all of the watersheds, the more the order of LH-moments and the return periods increased, the more RE became, while the less RRMSE and RBIAS became. The Absolute Relative Reduction (ARR) for the design flood was computed. The more the order of LH-moments increased, the less ARR of all applied watershed became It was confirmed that confidence efficiency of estimated design flood was increased as the order of LH-moments increased. Consequently, design floods for the appled watersheds were derived by the methods of L3 and L4-moments among LH-moments in view of high confidence efficiency.

• Journal of Korea Water Resources Association
• /
• v.57 no.5
• /
• pp.359-369
• /
• 2024

Korea prepares for potential floods by designating June 21st to September 20th as the flood season. However, many dams in Korea have suffered from extreme floods caused by different climate patterns, as in the case of the longest consecutive rain of 54 days in the 2020's flood season. In this context, various studies have tried to develop novel methodologies to reduce flood damage, but no study has ever dealt with the validity of the current statutory flood season thus far. This study first checked the validity of the current flood season through the observation data in the 21st century and proved that the current flood season does not consider the effects of increasing precipitation trends and the changing regional rainfall characteristics. In order to deal with these limitations, this study suggested seven new alternative flood seasons in the research area. The rigid reservoir operation method (ROM) was used for reservoir simulation, and the long short-term memory (LSTM) model was used to derive predicted inflow. Finally, all alternatives were evaluated based on whether if they exceeded the design discharge of the dam and the design flood of the river. As a result, the floods in the shifted period were reduced by 0.068% and 0.33% in terms of frequency and duration, and the magnitude also decreased by 24.6%, respectively. During this period, the second evaluation method also demonstrated that flood decreased from four to two occurrences. As the result of this study, the authors expect a formal reassessment of the flood season to take place, which will ultimately lead to the preemptive flood response to changing precipitation patterns.

• Journal of Korea Water Resources Association
• /
• v.41 no.5
• /
• pp.517-525
• /
• 2008

Regional rainfall quantile depends on the identification of hydrologically homogeneous regions. Various variables relevant to precipitation can be used to form regions. Since the type and number of variables may lead to improve the efficiency of partitioning, it is important to select those precipitation related variables, which represent most of the information from all candidate variables. Multivariate analysis techniques can be used for this purpose. Procrustes analysis which can decrease the dimension of variables based on their correlations, are applied in this study. 42 rainfall related variables are decreased into 21 ones by Procrustes analysis. Factor analysis is applied to those selected variables and then 5 factors are extracted. Fuzzy-c means technique classifies 68 stations into 6 regions. As a result, the GEV distributions are fitted to 6 regions while the lognormal and generalized logistic distributions are fitted to 5 regions. For the comparison purpose with previous results, rainfall quantiles based on generalized logistic distribution are estimated by at-site frequency analysis, index flood method, and regional shape estimation method.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.43 no.6
• /
• pp.721-733
• /
• 2023

As the frequency of extreme rainfall events increase due to climate change, climate change adaptation measures have been proposed by the central and local governments. In order to reduce flood damage in urban areas, various flood response policies, such as low impact development techniques and enhancement of the capacity of rainwater drainage networks, have been proposed. When these policies are established, regional characteristics and policy-effectiveness from the cost-benefit perspective must be considered for the flood mitigation measures. In this study, capacity enhancement of rainwater pipe networks and low impact development techniques including green roof and permeable pavement techniques are selected. And the flood reduction effect of the target watershed, Gwanak campus of Seoul National University, was analyzed using SWMM model which is an urban runoff simulation model. In addition, along with the quantified urban flooding reduction outputs, construction and operation costs for various policy scenarios were calculated so that cost-benefit analyses were conducted to analyze the effectiveness of the applied policy scenarios. As a result of cost-benefit analysis, a policy that adopts both permeable pavement and rainwater pipe expansion was selected as the best cost-effective scenario for flood mitigation. The research methodology, proposed in this study, is expected to be utilized for decision-making in the planning stage for flood mitigation measures for each region.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2008.05a
• /
• pp.2249-2253
• /
• 2008

본 연구에서는 지점빈도분석과 지역빈도분석을 이용하여 확률홍수량을 산정 하였다. 지점빈도 분석은 Annual Maximum Series(AMS) 및 Partial Duration Series(PDS)를 이용하여 자료를 추출하고 각 자료에 적합한 확률분포를 이용하여 확률홍수량을 산정하였다. 그러나 AMS를 이용한 확률홍수량의 산정은 표본의 개수가 부족하면 이에 따른 변동성(variability)이 커지게 되는 단점이 존재하며, PDS를 사용하면 임계값(threshold)에 따른 주관적 영향이 결과에 반영되는 단점이 존재하는 것으로 알려져 있다. 따라서 본 연구에서는 PDS를 사용하는 경우의 단점을 해결하기 위해 연 1.7회의 발생횟수를 갖는 자료를 추출하고 몬테카를로 모의시험을 통하여 주관적 영향을 제거하였다. 또한 두 가지 방법에 의해 산정된 확률홍수량의 비교검토를 위해 지역빈도분석을 수행하였다. 유역의 면적과 일평균강우량으로부터 확률홍수량을 산정할 수 있는 것으로 알려진 Bayesian-Generalized Least Square(B-GLS) 방법을 이용하여 확률홍수량을 산정하였다. 최종적으로 안양천 유역의 13개 소유역에 대한 세 가지 방법에 의해 산정된 확률홍수량을 비교 검토한 결과, 특정한 방법이 항상 우수하다는 결론은 얻을 수 없었으나 각 유역별로 AMS가 가장 크고 B-GLS가 가장 작은 확률홍수량을 갖는 경향을 나타내었다.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.23 no.1
• /
• pp.15-29
• /
• 2020

Recently, the incidence of flooding in Korea has decreased by the measures by central and local governments, however the scale of damage is increasing due to the improvement of living standard. One of the causes of such flood damage is natural causes such as rainfall exceeding the planned frequency of flood control under climate change. In addition, there are artificial causes such as encroachment of river spaces and management problems in upstream basins without consideration of downstream damage potential by regional development flood. In this study, in order to reduce the inundation damage caused by flooding of river, the situation at the time of inundation damage was reproduced by the detailed topographic data and 2D numerical model. Therefore, the effect of preparing various disaster prevention measures for the lowland was simulated in advance so that quantitative evaluation could be achieved. The target area is Taehwa river basin, where flooding was caused by the flooding of river waters caused by typhoon Chaba in October 2016. As a result of rainfall-discharge and two-dimensional analysis, the simulation results agree with the observed in terms of flood depth, flood arrival time and flooded area. This study examined the applicability of hydraulic analysis on river using two-dimensional inundation model, by applying detailed topographic data and it is expected to contribute to establish of disaster prevention measures.

• Journal of Korea Water Resources Association
• /
• v.42 no.6
• /
• pp.465-480
• /
• 2009

In this study, single and multiple linear regression model were used to derive the relationship between precipitation and altitude, latitude and longitude in Jejudo. The single linear regression analysis was focused on whether orographic effect was existed in Jejudo by annual average precipitation, and the multiple linear regression analysis on whether orographic effect was applied to each duration and return period of quantile from regional frequency analysis by index flood method. As results of the regression analysis, it shows the relationship between altitude and precipitation strongly form a linear relationship as the length of duration and return period increase. The multiple linear regression precipitation estimates(which used altitude, latitude, and longitude information) were found to be more reasonable than estimates obtained using altitude only or altitude-latitude and altitude-longitude. Especially, as results of spatial distribution analysis by kriging method using GIS, it also provides realistic estimates for precipitation that the precipitation was occurred the southeast region as real climate of Jejudo. However, the accuracy of regression model was decrease which derived a short duration of precipitation or estimated high region precipitation even had long duration. Consequently the other factor caused orographic effect would be needed to estimate precipitation to improve accuracy.