Estimation of Time-variant Probable Maximum Precipitation for South Korea

김남원,이정우 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.3

The objective of this study is to suggest a methodology for estimating the time-variant probable maximum precipitation. First, the greatest amount of precipitation for a relatively long duration, e.g., a month or longer, defined as the Long-term Probable Maximum Precipitation (LPMP) in the present work was estimated. Then, the procedure for using the LPMP estimates for determining the temporally varied upper limit of precipitation during a certain period of the year, defined as the time-variant PMP (TPMP) in this study was implemented. Hershfield's statistical approach was used to estimate LPMP, i.e., monthly, calendar monthly, and cumulative monthly, for each of 61 weather stations located in South Korea, and nationwide distribution maps of three types of LPMP were made. In particular, using the cumulative monthly PMP estimates and total antecedent precipitation prior to a certain time, the TPMP for a certain duration was forecast for example problems. From the case study for precipitation data at Chungju weather station, TPMP forecasts at certain stormy periods were substantially smaller than the design PMP, which implies that reservoir operation for flood control based on the design PMP may be too restrictive for some period. It is expected that the TPMP can serve as a complementary index to increase the water supply of a reservoir.

통계학적 가능최대강수량의 재현기간 추정

심인경,이옥정,정상만,김상단 한국방재학회 2019 한국방재학회논문집 Vol.19 No.1

This study proposes a simple alternative to statistically estimate the Probable Maximum Precipitation (PMP). The PMP is the upper limit of physical rainfall depth and is contradictory to the concept of probability. However, since the upper limit of physical rainfall depth cannot be identified clearly from observed data, it was judged that making a probabilistic estimation of PMP might be reasonable. Hershfield's km, calculated from the daily rainfall depth recorded at 80 stations of the Automated Synoptic Observing System (ASOS) with more than 10 years of observations, was fitted to the Generalized Extreme Value (GEV) distribution with a shape parameter given as a linear function of the average of the annual maximum of the time series at each observation site. Data from the oldest 15 sites in Korea (1961-2017, 57 years) were used to verify the methodology suggested in this study. Hershfield's statistical PMPs and the hydro-meteorological PMPs were somewhat different; however, the return period for the PMPs in terms of daily rainfall depth was estimated to be approximately 20,000,000 years at all sites studied. 본 연구에서는 가능최대강수량(Probable Maximum Precipitation, PMP)을 통계학적으로 추정하는 간단한 대안이 제시된다. PMP는 물리적인 강우량 상한계로, 확률론적 개념과는 모순적이지만, 관측자료로부터는 물리적인 강우량의 상한계를 명확하게 규정할 수 없기 때문에, PMP를 확률론적으로 구하는 방법이 합리적일 수도 있다고 판단하였다. 10년 이상의 관측자료를 보유한 기상청 ASOS 80개 지점의 일 강우량 자료를 이용하여 산출한 Hershfield의 km은 각 관측 지점의 연 최대 시계열의 평균의 선형함수로 주어지는 형상 매개변수를 가지는 GEV 분포에 적합한 것으로 나타났다. 또한, 본 연구의 방법을 검증하기 위하여 우리나라에서 가장 오래된 15개 지점 자료(1961-2017, 57년)가 이용되었다. Hershfield의 통계학적 PMP와 수문기상학적인 PMP는 지점별로 다소 상이하였으나, 적용된 지점들 모두에서 일 강우량 PMP의 재현기간은 대략 20,000,000년인 것으로 추정되었다.

가강수량 특성을 이용한 극치호우의 기후변화 예측

박민규,박무종,김상단,주진걸,Park,Minkyu,Park,Moojong,Kim,Sangdan,Joo,Jingul 한국방재학회 2013 한국방재학회논문집 Vol.13 No.1

본 연구에서는 RCP 8.5 기후변화 시나리오를 고려하여 극치호우로서 가능최대강수량의 변화를 예측하였다. 기존의 기후변화에 따른 극치호우 예측은 평균적인 모델링 결과를 기초로 하고 있어 극한값의 재현이나 거동 예측과 관련하여 많은 문제점이 지적되어왔다. 이와 관련하여 본 연구에서는 기후변화 시나리오에서 가장 신뢰도가 높은 기온의 변화와 물리적으로 상관성이 높은 가강수량 추정방법을 이용하여 가능최대강수량의 규모를 직접 추정하는 방법을 적용하였다. 그 결과 국내 가능최대강수량의 규모가 향후 100년 이후 약 40% 정도까지 증가할 수 있는 것으로 나타났다. 이러한 결과는 확률강우량의 변동폭 등과 관련해서도 간접적인 참고수치로 이용가능 할 것으로 기대된다. In this study, probable maximum precipitation change was predicted using RCP 8.5 IPCC climate change scenario as extreme storm change. The modelling results based on average have the restriction on extreme rainfall value representation and future behavior prediction. To overcome these problems, this study uses air temperature change and precipitable water relationship in order to calculate the magnitude of probable maximum precipitation. The results showed about 40% increase in probable maximum precipitation. These were expected to use as reference of extreme storm increase such as IDF changes.

정량적 수해위험도 평가를 위한 세계 주요도시 강우특성의 비교연구

박민규,박무종,신상영,유철상 한국방재학회 2011 한국방재학회논문집 Vol.11 No.3

The desire for living without hazardous damages grows these days, the city strategy to make the safer community has become an issue. The global assessment for the flood index require the process considering different climate of the world cities. In this study, the actual rainfall observations of the world's major cities were collected. To compare different rainfall characteristics, we calculated some indicators such as frequency factor etc using the probable maximum precipitation. Using the results of these indicators, major cities in Korea show greater variability in the rainfall characteristics when compared to other major cities in the world. These results are expected to be useful for the development of global flood risk assessment as well as the setting the direction for future flood prevention measures. 재해의 위험으로부터 안전을 추구하는 시민들의 욕구는 계속 증가하고 있으며 이와 관련하여 최근 안전도시 만들기 등이 이슈가 되고 있다. 기후 및 기상특성이 상이한 세계 도시들을 대상으로 안전도시로서 평가를 받으려면 각 도시가 처한 재해위험성을 평가하는 과정이 필요하다. 본 연구에서는 이와 관련하여 세계 주요도시의 실제 관측 강우량을 수집하였다. 서로 다른 특성을 가지는 강우를 비교하기 위해 특정 지역에서 최대로 발생가능할 것으로 예상되는 가능최대강수량을 이용하여 빈도계수 등 여러 가지 지표를 계산해보았다. 이러한 지표를 이용한 결과 우리나라 주요 도시가 보여주는 강우특성을 고찰할 수 있었다. 우리나라 호우의 강수량은 변동성이 다른 세계 주요 도시와 비교할 때 상대적으로 큰 특성을 가지고 있었다. 이러한 비교 결과들은 세계도시를 대상으로 하는 수해위험도 평가방법의 개발뿐만 아니라 향후 수해방지대책의 방향설정에 유용하게 사용될 수 있을 것으로 판단된다.

Bayesian Regression Model for Seasonal Forecast of Precipitation over Korea

조성일,임예지,이재용,Hyun-Suk Kang,오희석 한국기상학회 2012 Asia-Pacific Journal of Atmospheric Sciences Vol.48 No.3

In this paper, we apply three different Bayesian methods to the seasonal forecasting of the precipitation in a region around Korea (32.5oN-42.5oN, 122.5oE-132.5oE). We focus on the precipitation of summer season (June-July-August; JJA) for the period of 1979-2007 using the precipitation produced by the Global Data Assimilation and Prediction System (GDAPS) as predictors. Through cross-validation, we demonstrate improvement for seasonal forecast of precipitation in terms of root mean squared error (RMSE) and linear error in probability space score (LEPS). The proposed methods yield RMSE of 1.09 and LEPS of 0.31 between the predicted and observed precipitations, while the prediction using GDAPS output only produces RMSE of 1.20 and LEPS of 0.33 for CPC Merged Analyzed Precipitation (CMAP) data. For stationmeasured precipitation data, the RMSE and LEPS of the proposed Bayesian methods are 0.53 and 0.29, while GDAPS output is 0.66and 0.33, respectively. The methods seem to capture the spatial pattern of the observed precipitation. The Bayesian paradigm incorporates the model uncertainty as an integral part of modeling in a natural way. We provide a probabilistic forecast integrating model uncertainty.

전국 확률강수량 산정을 위한 비정상성 빈도해석 기법의 적용

김광섭,이기춘,Kim, Gwang-Seob,Lee, Gi-Chun 한국농공학회 2012 한국농공학회논문집 Vol.54 No.5

In this study, we estimated probable precipitation amounts at the target year (2020, 2030, 2040) of 55 weather stations in Korea using the 24 hour annual maximum precipitation data from 1973 through 2009 which should be useful for management of agricultural reservoirs. Not only trend tests but also non-stationary tests were performed and non-stationary frequency analysis were conducted to all of 55 sites. Gumbel distribution was chosen and probability weighted moment method was used to estimate model parameters. The behavior of the mean of extreme precipitation data, scale parameter, and location parameter were analyzed. The probable precipitation amount at the target year was estimated by a non-stationary frequency analysis using the linear regression analysis for the mean of extreme precipitation data, scale parameter, and location parameter. Overall results demonstrated that the probable precipitation amounts using the non-stationary frequency analysis were overestimated. There were large increase of the probable precipitation amounts of middle part of Korea and decrease at several sites in Southern part. The non-stationary frequency analysis using a linear model should be applicable to relatively short projection periods.

HEC-HMS와 HEC-RAS를 이용한 댐 붕괴 해석

홍승진(Hong Seung-Jin),김수전(Kim Soo-Jun),김형수(Kim Hung-Soo),경민수(Kyung Min-Soo) 대한토목학회 2009 대한토목학회논문집 B Vol.29 No.4B

본 연구에서는 HEC-HMS와 HEC-RAS 모형을 이용하여 소양강댐에 가능최대강수량이 발생하여 소양강댐이 붕괴할 경우 두 모형간의 소양강댐 직하류의 유출량을 산정해 그 결과를 비교하였다. 가능최대강수량은 태풍 루사의 호우사상을 사용하여 강릉지역의 면적별평균강우량과 수분최대화방법을 이용하여 산정하였다. 산정된 가능최대강수량은 지속시간(6 hr, 12 hr, 18 hr, 24 hr)별로 각각을 비교하였으며, HEC-HMS 모형의 입력자료로 이용하였고, HEC-HMS로 산정되어진 유입량자료를 HEC-RAS에서의 유입량 자료로 이용하여 부정류 해석을 실시하였다. 두 모형의 댐 붕괴 조건은 동일하게 입력하였으며, HEC-HMS 모형으로 산정되어진 첨두유출량은 HEC-RAS 모형보다 크게 산정되었다. HEC-RAS와 HEC-RAS와 댐 붕괴 해석을 이용해 두 모형의 적용성을 판단하였는데, HEC-HMS 모형보다는 HEC-RAS 모형이 댐 붕괴 해석에 대한 적용성에서 보다 실제에 가까운 모의를 할 수 있었다. 하지만 HEC-HMS 모형은 자료 구축이 용이하다는 측면에서 신속한 댐 붕괴 모의를 필요로 할 때 적용성이 있을 것으로 판단된다. 두 모형의 경우 댐 붕괴 해석에 대한 정확한 자료와 함께 각기 다른 붕괴해석 개념에 대한 가이드라인의 생성이 중요하다고 판단된다. 또한 두 모형이 모두 불확실성을 포함하고 있기 때문에 보다 자세한 지형인자와 실제 하천과 비슷한 자료의 구축의 필요성이 있다고 판단된다. This study simulates the dam break situation by a probable maximum precipitation of Soyang-River Dam using HEC-HMS model and HEC-RAS model and compares the simulated results. The probable maximum precipitation was calculated using the flood event of the typhoon Rusa occurred in 2002 and using the mean areal precipitation of the Gangreung region and the moisture maximization method. The estimated probable maximum precipitations were compared for the duration of 6, 12, 18, and 24 hrs and were used as input data for the HEC-HMS model. Moreover, the inflow data calculated by HEC-HMS were utilized as ones for HEC-RAS, and then unsteady flow analysis was conducted. The two models were used for the dam break analysis with the same conditions and the peak flow estimated by HEC-HMS was larger than that of the HEC-RAS model. The applicability of two models was performed from the dam break analysis then we found that we could simulate more realistic peak flow by HEC-RAS than HEC-HMS. However, when we need more fast simulation results we could use HEC-HMS. Therefore, we may need the guidelines for the different utilizations with different purposes of two models. Furthermore, since the two models still include uncertainties, it is important to establish more detailed topographical factors and data reflecting actual rivers.

Power 모형을 이용한 비정상성 확률강수량 산정

김광섭,이기춘,김병권,Kim, Gwangseob,Lee, Gichun,Kim, Beungkown 한국농공학회 2014 한국농공학회논문집 Vol.56 No.4

In this study, we performed a non-stationary frequency analysis using a power model and the model was applied for Seoul, Daegu, Daejeon, Mokpo sites in Korea to estimate the probable precipitation amount at the target years (2020, 2050, 2080). We used the annual maximum precipitation of 24 hours duration of precipitation using data from 1973 to 2009. We compared results to that of non-stationary analyses using the linear and logistic regression. The probable precipitation amounts using linear regression showed very large increase in the long term projection, while the logistic regression resulted in similar amounts for different target years because the logistic function converges before 2020. But the probable precipitation amount for the target years using a power model showed reasonable results suggesting that power model be able to reflect the increase of hydrologic extremes reasonably well.

월 PMP 개념의 적용에 관한 연구

최한규,김남원,최용묵,윤희섭 江原大學校 産業技術硏究所 2001 産業技術硏究 Vol.21 No.B

Normally at a flood season the operation of the dam depends on a short range weather forecast that makes many difficulties of the management at a dry season. It is needed to study the pattern of the long period rainfall. The concept of PMP(Probable Maximum Precipitation) was used for designing dam. From the concept, this study is applied the concept of monthly probable maximum precipitation for operating dam. It can be possible to let us know the appropriateness of a limiting water level at a rainy season. For the operation of dam at a dry season this study can predict roughly the flood season's pattern of precipitation by month or period, therfore the prediction of precipitation can rise efficient operation of a dam.

월 PMP 개념의 적용에 관한 연구

최한규(Choi Han Kyu),김남원(Kim Nam Won),최용묵(Choi Yong Mook),윤희섭(Yoon Hee Sub) 강원대학교 산업기술연구소 2001 産業技術硏究 Vol.21 No.1

Normally at a flood season the operation of the dam depends on a short range weather forecast that makes many difficulties of the management at a dry season. It is needed to study the pattern of the long period rainfall. The concept of PMP(Probable Maximum Precipitation) was used for designing dam. From the concept, this study is applied the concept of monthly probable maximum precipitation for operating dam. It can be possible to let us know the appropriateness of a limiting water level at a rainy season. For the operation of dam at a dry season this study can predict roughly the flood season’s pattern of precipitation by month or period, therfore the prediction of precipitation can rise efficient operation of a dam.