• Title, Summary, Keyword: Heavy rainfall

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A Study on the development of a heavy rainfall risk impact evaluation matrix (호우위험영향평가 매트릭스 개발에 관한 연구)

  • Jung, Seung Kwon;Kim, Byung Sik
    • Journal of Korea Water Resources Association
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    • v.52 no.2
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    • pp.125-132
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    • 2019
  • In this study, we developed a heavy rainfall risk impact matrix, which can be used to evaluate the influence of heavy rainfall risk, and propose a method to evaluate the impact of heavy rainfall risk. We evaluated the heavy rainfall risk impact for each receptor (Residential, Transport, Utility) on Sadang-dong using the heavy rainfall event on July 27, 2011. For this purpose, the potential risk impact was calculated by combining the impact level and the rainfall depth based on the grid. Heavy Rainfall Risk Impact was calculated by combining with Likelihood to predict the heavy rainfall impact, and the degree of heavy rainfall in the Sadang-dong area was analyzed and presented based on grid.

An improvement on the Criteria of Special Weather Report for Heavy Rain Considering the Possibility of Rainfall Damage and the Recent Meteorological Characteristics (최근 기상특성과 재해발생이 고려된 호우특보 기준 개선)

  • Kim, Yeon-Hee;Choi, Da-Young;Chang, Dong-Eon;Yoo, Hee-Dong;Jin, Gee-Beom
    • Atmosphere
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    • v.21 no.4
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    • pp.481-495
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    • 2011
  • This study is performed to consider the threshold values of heavy rain warning in Korea using 98 surface meteorological station data and 590 Automatic Weather System stations (AWSs), damage data of National Emergency Management Agency for the period of 2005 to 2009. It is in need to arrange new criteria for heavy rain considering concept of rainfall intensity and rainfall damage to reflect the changed characteristics of rainfall according to the climate change. Rainfall values from the most frequent rainfall damage are at 30 mm/1 hr, 60 mm/3 hr, 70 mm/6 hr, and 110 mm/12 hr, respectively. The cumulative probability of damage occurrences of one in two due to heavy rain shows up at 20 mm/1 hr, 50 mm/3 hr, 80 mm/6 hr, and 110 mm/12 hr, respectively. When the relationship between threshold values of heavy rain warning and the possibility of rainfall damage is investigated, rainfall values for high connectivity between heavy rain warning criteria and the possibility of rainfall damage appear at 30 mm/1 hr, 50 mm/3 hr, 80 mm/6 hr, and 100 m/12 hr, respectively. It is proper to adopt the daily maximum precipitation intensity of 6 and 12 hours, because 6 hours rainfall might be include the concept of rainfall intensity for very-short-term and short-term unexpectedly happened rainfall and 12 hours rainfall could maintain the connectivity of the previous heavy rain warning system and represent long-term continuously happened rainfall. The optimum combinations of criteria for heavy rain warning of 6 and 12 hours are 80 mm/6 hr or 100 mm/12 hr, and 70 mm/6 hr or 110 mm/12 hr.

Application of Images and Data of Satellite to a Conceptual Model for Heavy Rainfall Analysis (호우사례 분석을 위한 개념모델 구성에 위성영상과 위성자료의 활용 연구)

  • Lee, Kwang-Jae;Heo, Ki-Young;Suh, Ae-Sook;Park, Jong-Seo;Ha, Kyung-Ja
    • Atmosphere
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    • v.20 no.2
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    • pp.131-151
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    • 2010
  • This study establishes a conceptual model to analyze heavy rainfall events in Korea using multi-functional transport satellite-1R satellite images. Three heavy rainfall episodes in two major synoptic types, such as synoptic low (SL) type and synoptic flow convergence (SC) type, are analyzed through a conceptual model procedure which proceeds on two steps: 1) conveyer belt model analysis to detect convective area, and 2) cloud top temperature analysis from black body temperature (TBB) data to distinguish convective cloud from stratiform cloud, and eventually estimate heavy rainfall area and intensity. Major synoptic patterns causing heavy rainfall are Changma, synoptic low approach, upper level low in the SL type, and upper level low, indirect effect of typhoon, convergence of tropical air in the SC type. The relationship between rainfall and TBBs in overall well resolved areas of heavy rainfall. The SC type tended to underestimate the intensity of heavy rainfall, but the analysis with the use of water vapor channel has improved the performance. The conceptual model improved a concrete utilization of images and data of satellite, as summarizing characteristics of major synoptic type causing heavy rainfall and composing an algorism to assess the area and intensity of heavy rainfall. The further assessment with various cases is required for the operational use.

A Numerical Simulation Study of Orographic Effects for a Heavy Rainfall Event over Korea Using the WRF Model (WRF 모형을 이용한 한반도 집중 호우에 대한 지형 효과의 수치 모의 연구)

  • Lee, Ji-Woo;Hong, Song-You
    • Atmosphere
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    • v.16 no.4
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    • pp.319-332
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    • 2006
  • This study examines the capability of the WRF (Weather Research and Forecasting) model in reproducing heavy rainfall that developed over the Korean peninsula on 26-27 June 2005. The model is configured with a triple nesting with the highest horizontal resolution at a 3-km grid, centered at Yang-dong, Gyeonggi-province, which recorded the rainfall amount of 376 mm. In addition to the control experiment employing realistic orography over Korea, two consequent sensitivity experiments with 1) no orography, and 2) no land over Korea were designed to investigate orographic effects on the development of heavy rainfall. The model was integrated for 48 hr, starting at 1200 UTC 25 June 2005. The overall features of the large-scale patterns including a cyclone associated with the heavy rainfall are reasonably reproduced by the control run. The spatial distribution of the simulated rainfall over Korea agreed fairly well with the observed. The amount of predicted maximum rainfall at the 3-km grid is 377 mm, which located about 50 km southeast from the observed point, Yang-Dong, indicating that the WRF model is capable of predicting heavy rainfall over Korea at the cloud resolving resolutions. Further, it was found that the complex orography over the Korean peninsula plays a role in enhancing the rainfall intensity by about 10%. The land-sea contrast over the peninsula was fund to be responsible for additional 10% increase of rainfall amount.

A Study on the Heavy Rainfall Cases Associated with Low Level Jet Inflow along the Changma Front (장마전선상에서 하층제트 유입으로 인한 집중호우에 관한 연구)

  • Choi, Ji-Young;Shin, Ki-Chang;Ryu, Chan-Su
    • Journal of the Chosun Natural Science
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    • v.4 no.1
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    • pp.44-57
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    • 2011
  • In general, heavy rainfall in Korea is mostly associated with inflow of 850hPa low-level jet. It transports abundant heat and moisture flux to the Changma front. In this study, synoptic characteristics of heavy rainfall in Korea from a case study is examined by classifying heavy rainfall cases with synoptic patterns, in particular distribution of upper- and low-level jets, western North Pacific high, and moisture flux. The surface and upper-level weather charts including auxiliary analysis chart and radar and satellite images obtained from the Korea Meteorological Administration, and 500hPa geopotential heights from NCEP/NCAR are used and then KLAPS is applied to understand the local atmospheric structure associated with heavy rainfall. Results show that maximum frequency in 60 heavy rainfall cases with more than 150mm/day appears in the Changma type of 43 cases (a proportion in relation to a whole is 52%) including the combined Changma types with typhoon and cyclone. As indicated in previous studies, most heavy rainfall cases are related to inflow of low-level jet. In addition, synoptic characteristics based on the analyses of weather charts, radar and satellite images, and KLAPS in heavy rainfall case of 12 July, 2009 reveal that the atmospheric vertical structure in particular equivalent potential temperature favorable for effective inflow of warm and moist southwesterly into the Changma front is linked to large potential instability and the strong convergence accompanied with low-level jet around Suwon contributes to atmospheric upsliding along the Changma front, producing heavy rainfall.

Heavy Rainfall prediction using convective instability index (대류성 불안정 지수를 이용한 집중호우 예측)

  • Kim, Young-Chul;Ham, Sook-Jung
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.17 no.1
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    • pp.17-23
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    • 2009
  • The purpose of this study is possibility of the heavy rainfall prediction using instability index. The convective instability index using this study is Convective Available Potential Energy(CAPE) concerned the growth energy of the storm, Bulk Richardson Number(BRN) concerned the type and strength of the storm, and Sotrm Relative Helicity(SRH) concerned maintenance of the storm. To verify the instability index, the simulation of heavy rainfall case experiment by Numerical Weather Prediction(NWP) model(MM5) are designed. The results of this study summarized that the heavy rainfall related to the high instability index and the proper combination of one more instability index made the higher heavy rainfall prediction.

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A Study on the Characteristics of the Heavy Rainfall Events in Honam District along the Border of mT Airmass

  • Yang, Se-Hwan;Ryu, Chan-Su
    • Journal of the Chosun Natural Science
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    • v.5 no.4
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    • pp.220-228
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    • 2012
  • District of Korea affected by westerly wind and heavy rainfall is predominantly distributed in the west and south of Honam district. So, this study is becoming a necessity. In this study, it is investigated that the characteristics of heavy rainfall occurred frequently in Honam district along the border of mT airmass after the end of rainy season due to atmospheric instability, lower (850 hPa) convergence and topographic effect. Our results show that heavy rainfall occurred in Honam district along the border of mT airmass results from the appropriate mechanism of the unstable vertical structure and moisture flux in the expansion and contraction of the border of mT airmass. All things considered, the improvement of the predictability of heavy rainfall occurred in Honam district along the border of mT airmass could be possible by the generalization of the results of this study.

Rainfall analysis considering watershed characteristics and temporal-spatial characteristics of heavy rainfall (집중호우의 시·공간적 특성과 유역특성을 고려한 강우분석 연구)

  • Kim, Min-Seok;Choi, Ji-Hyeok;Moon, Young-Il
    • Journal of Korea Water Resources Association
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    • v.51 no.8
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    • pp.739-745
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    • 2018
  • Recently, the incidence of heavy rainfall is increasing. Therefore, a rainfall analysis should be performed considering increasing frequency. The current rainfall analysis for hydrologic design use the hourly rainfall data of ASOS with a density of 36 km on the Korean Peninsula. Therefore, medium and small scale watershed included Thiessen network at the same rainfall point are analyzed with the same design rainfall and time distribution. This causes problem that the watershed characteristics can not be considered. In addition, there is a problem that the temporal-spatial change of the heavy rainfall occurring in the range of 10~20 km can not be considered. In this study, Author estimated design rainfall considering heavy rainfall using minutely rainfall data of AWS, which are relatively dense than ASOS. Also, author analyzed the time distribution and runoff of each case to estimate the huff's method suitable for the watershed. The research result will contribute to the estimation of the design hydrologic data considering the heavy rainfall and watershed characteristics.

A Study on Variability of Extreme Precipitation by Basin in South Korea (한국의 유역별 호우변화에 관한 연구)

  • Lee, Seung-Ho;Kim, Eun-Kyung;Heo, In-Hye
    • Journal of the Korean association of regional geographers
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    • v.17 no.5
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    • pp.505-520
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    • 2011
  • This study is aimed to examine the change on extreme precipitation events in South Korea. The country is divided into six basins, and seven extreme precipitation indices-related to heavy rainfall are analyzed at sixty weather stations. The increasing trend in amount of heavy rainfall is more stable than that in days of heavy rainfall. The increasing trend is the most stable when days of rainfall are more than 50 mm, or rainfall is over the 95th percentile. The precipitation indices-related to heavy rainfall was mostly increasing during analysis period. Especially, basins of the Han river, the upper Nakdong river, and the Eastern coast show significantly increasing trends compared to the other basins. However, the increasing trends of the Geum river and the Seomjin river are not statistically significant. Heavy rainfall events had stably increased in the Han and the Nakdong rivers since the mid-1970s. However, the number of stably increasing regions has decreased since the mid-2000s. It means that the frequency and intensity of the recent heavy rainfall become more irregular.

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Studies on the Predictability of Heavy Rainfall Using Prognostic Variables in Numerical Model (모델 예측변수들을 이용한 집중호우 예측 가능성에 관한 연구)

  • Jang, Min;Jee, Joon-Beom;Min, Jae-sik;Lee, Yong-Hee;Chung, Jun-Seok;You, Cheol-Hwan
    • Atmosphere
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    • v.26 no.4
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    • pp.495-508
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    • 2016
  • In order to determine the prediction possibility of heavy rainfall, a variety of analyses was conducted by using three-dimensional data obtained from Korea Local Analysis and Prediction System (KLAPS) re-analysis data. Strong moisture convergence occurring around the time of the heavy rainfall is consistent with the results of previous studies on such continuous production. Heavy rainfall occurred in the cloud system with a thick convective clouds. The moisture convergence, temperature and potential temperature advection showed increase into the heavy rainfall occurrence area. The distribution of integrated liquid water content tended to decrease as rainfall increased and was characterized by accelerated convective instability along with increased buoyant energy. In addition, changes were noted in the various characteristics of instability indices such as K-index (KI), Showalter Stability Index (SSI), and lifted index (LI). The meteorological variables used in the analysis showed clear increases or decreases according to the changes in rainfall amount. These rapid changes as well as the meteorological variables changes are attributed to the surrounding and meteorological conditions. Thus, we verified that heavy rainfall can be predicted according to such increase, decrease, or changes. This study focused on quantitative values and change characteristics of diagnostic variables calculated by using numerical models rather than by focusing on synoptic analysis at the time of the heavy rainfall occurrence, thereby utilizing them as prognostic variables in the study of the predictability of heavy rainfall. These results can contribute to the identification of production and development mechanisms of heavy rainfall and can be used in applied research for prediction of such precipitation. In the analysis of various case studies of heavy rainfall in the future, our study result can be utilized to show the development of the prediction of severe weather.