확률강우량을 초과하는 호우사상의 발생특성 분석

조덕준,전병훈 한국방재학회 2012 한국방재학회논문집 Vol.12 No.2

The present paper describes applicability in practice for the design rainfall by the analysis of characteristics of the probability rainfall. In general, the size of hydraulic structures is determined by the rainfall suitability of the design rainfall is very important. To this end, in the last 50 years historical hourly rainfall data for each return period and duration of rainfall issued by more than the probability for rainfall occurrence and rainfall characteristics such as size and periodicity causes were analyzed. In addition,the annual trend of average rainfall events greater than the probability were analyzed. This study shows excess rainfall caused by the number of occurrence of rainfall return period were much more than that, the average rainfall exceeds the rainfall was growing up. Therefore, to adopt the probable rainfall as the design rainfall can not meet the flood protection as it aims. 본 연구에서는 확률강우량의 특성분석을 통하여 실무 설계강우량의 적합성을 평가하였다. 일반적으로 수공구조물의 크기는 강우량으로 결정되므로 설계강우량의 적합성은 매우 중요한 요소이다. 이를 위하여 지난 50년간의 시간강우자료에 대하여 각 재현기간 및 지속시간별로 확률강우량 보다 큰 호우사상에 대하여 발생횟수, 호우규모 등의 특성과 발생주기성 등을 분석하였다. 또한 확률강우량보다 큰 호우사상들의 평균값에 대한 연변화 추세를 분석하였다. 연구결과 확률강우량을 초과하여 발생한 호우사상의 발생도수가 재현기간을 크게 상회하였으며, 초과호우사상의 평균강우량도 증가하는 추세로 나타났다. 이는 현재의 확률강우량을 그대로 설계강우량으로 적용하는 것은 목표로 하는 홍수방재을 충족시킬 수 없음을 의미한다.

Runoff Analysis of an Urban Drainage System Using Radar Rainfall: A Case Study of the Guro-Gu Town Drainage System, Seoul, Korea

Narae Kang,Yonsoo Kim,Hui Seung Noh,Hung Soo Kim 한국방재학회 2016 Journal of Disaster Management Vol.1 No.4

Rainfall has recently begun to show different properties in space and time. In particular, although localized heavy rainfall is frequent, rain gauges on the ground can only observe rainfall at one point. In other words, ground-based rain gauges have limitations in spatial and temporal resolution for measuring rainfall. As a result, there is a need to utilize radar rainfall measurements that can consider the spatial distribution of the change in rainfall based on the direction of the storm. In this study, we tried to apply radar rainfall for a runoff simulation of an urban drainage system. The study area was Guro-gu, Seoul City, Korea, and we divided the study area into sub-basins based on the rain gauge network of the AWS (Automatic Weather Station). Then, the radar rainfall data were adjusted using the rainfall data of the rain gauge stations, and the areal rainfall amounts were obtained. The runoffs were simulated using the XP-SWMM model in the sub-basins of an urban drainage system. As a result, the adjusted radar rainfalls underestimated the ground-based measurement data by 60 to 95%. Therefore, differences in runoffs simulated by the adjusted radar and the gauge rainfall amounts are found. The peak runoff time from the radar rainfall occurred earlier than that from the gauge rainfall. This result is due to the fact that the radar rainfall can reflect the spatial variability of the rainfall in time by taking into consideration the movement of a storm.

선행강우를 고려한 산사태 유발 강우기준(ID curve) 분석

홍문현,김정환,정경자,정상섬 한국지반공학회 2016 한국지반공학회논문집 Vol.32 No.4

This study was conducted to suggest a landslide triggering rainfall threshold (ID curve) for landslide prediction byconsidering the effect of antecedent rainfall. 202 rainfall data including domestic landslide and rainfall records wereused in this study. In order to consider the effect of antecedent rainfall, rainfall data were analyzed by changing InterEvent Time Definition (IETD) and IETD based ID curve were presented by regression analysis. Compared to the findingsof the previous studies, the presented ID curve has a tendency to predict the landslides occurring at a relatively lowrainfall intensity. It is shown that the proposed ID curve is appropriate and realistic for predicting landslides throughthe validation of proposed ID curve using records of landslides in 2014. Based on this analysis, it is found that thelonger IETD, the greater the effect of antecedent rainfall, and the steeper the gradient of ID curve. It is also foundthat the rainfall threshold (intensity) is higher for the short period rainfall and lower for the long period rainfall.

Uncertainty of Areal Average Rainfall and Its Effect on Runoff Simulation: A Case Study for the Chungju Dam Basin, Korea

유철상,김정호,윤정수 대한토목학회 2012 KSCE Journal of Civil Engineering Vol.16 No.6

This study investigated the relationship between the errors involved in the areal average rainfall estimation and the runoff simulation (hereafter, rainfall and runoff errors). The error statistics of the observed areal average rainfall were estimated and used for the generation of input data for the runoff simulation. The Clark instantaneous unit hydrograph was used for this runoff simulation. The runoff model parameters were estimated using several sets of rainfall-runoff data observed, whose statistics were then used for the sensitive analysis of the model simulation on the parameter sets. The rainfall error in this study was defined as the relative difference between the observed and generated areal average rainfall. On the other hand, the runoff error was designed to consider the runoff volume, peak flow and peak time, respectively. This study was applied to the Chugnju Dam Basin, Korea. The results obtained are as follows: (1) The variation of model parameters estimated in this study were about 30% of their means. Also, the effect of this error in model parameter estimation on runoff simulation was found to be maximum 15% of the peak flow. (2) The estimation error of areal average rainfall was found roughly proportional to the areal average rainfall itself. Both the rainfall and runoff errors were found to have no obvious biases. However, the variance of the peak flow error was found to be significantly higher. (3) The relationship between rainfall error and runoff volume error was roughly one to one, however, the rainfall error has become amplified by more than 50 % and transferred to the peak flow error.

Estimation of optimal runoff hydrograph using radar rainfall ensemble and blending technique of rainfall-runoff models

Lee, Myungjin,Kang, Narae,Kim, Jongsung,Kim, Hung Soo 한국수자원학회 2018 한국수자원학회논문집 Vol.51 No.3

최근 기후변화로 인한 국지성 호우 및 태풍 피해가 자주 발생하고 있다. 이와 같은 피해를 저감하기 위해서는 정확한 강우의 예측과 홍수량 산정이 필요하다. 그러나 지점 및 레이더 강우 시 ․ 공간적 오차를 포함하고 있고, 유출 모형에 의한 유출수문곡선 역시 보정을 실시하더라도 관측유량과 오차를 가지고 있어 불확실성이 존재한다. 따라서 본 연구에서는 확률론적 강우 앙상블을 생성하여 강우의 불확실성을 확인하였다. 또한 유출 결과를 통해 수문 모형의 불확실성을 확인하였고, 블랜딩 기법을 이용하여 하나의 통합된 유출 수문곡선을 제시하였다. 생성된 강우앙상블은 강우강도 및 지형적인 영향으로 레이더가 과소 관측이 될 때, 강우 앙상블의 불확실성이 큰 것을 확인하였고, 블랜딩 기법을 적용하여 산정된 최적 유출 수문곡선은 유출모형의 불확실성을 크게 줄이는 것으로 나타났다. 본 연구 결과를 활용한다면, 정확한 홍수량 산정 및 예측을 통해 집중호우로 인한 피해를 줄일 수 있을 것으로 판단된다. Recently, the flood damage by the localized heavy rainfall and typhoon have been frequently occurred due to the climate change. Accurate rainfall forecasting and flood runoff estimates are needed to reduce such damages. However, the uncertainties are involved in guage rainfall, radar rainfall, and the estimated runoff hydrograph from rainfall-runoff models. Therefore, the purpose of this study is to identify the uncertainty of rainfall by generating a probabilistic radar rainfall ensemble and confirm the uncertainties of hydrological models through the analysis of the simulated runoffs from the models. The blending technique is used to estimate a single integrated or an optimal runoff hydrograph by the simulated runoffs from multi rainfall-runoff models. The radar ensemble is underestimated due to the influence of rainfall intensity and topography and the uncertainty of the rainfall ensemble is large. From the study, it will be helpful to estimate and predict the accurate runoff to prepare for the disaster caused by heavy rainfall.

Rainfall variability over Zimbabwe and its relation to large‐scale atmosphere–ocean processes

Mamombe, Vimbai,Kim, WonMoo,Choi, Yong‐,Sang John Wiley Sons, Ltd 2017 International journal of climatology Vol.37 No.2

<P><B>ABSTRACT</B></P><P>The relationship between interannual variability of Zimbabwe rainfall and atmosphere–ocean interaction processes is established using high‐resolution rainfall station datasets. Empirical orthogonal function (EOF) analysis is used to extract the spatiotemporal modes that explain most of the variations in the rainfall pattern. Results suggest strong homogeneity in the rainfall pattern that is dominantly described by EOF mode 1. The correlation analysis of mode 1 with sea surface temperatures (SSTs) supports the assumption that El Niño Southern Oscillation (ENSO) has a significant influence on Zimbabwe summer rainfall. Significant correlations exist between rainfall and SSTs over large regions of the tropical Indian and Pacific Oceans. The seasonal response of rainfall to the southern annular mode is reflected in both modes 1 and 2. Mode 1 suggests homogeneity in rainfall variations within the country and mode 2 describes the north–south rainfall fluctuations in the country. Although the magnitudes of their loadings are small, modes 3 and 4 extracted distinct rainfall regions within the country. This could be attributed to the use of more reliable, higher resolution rainfall data. These findings will assist to bring profound improvements to seasonal rainfall forecasting techniques around the country.</P>

2011년 집중호우로 인한 산사태 발생특성 분석

김석우 ( Suk Woo Kim ),전근우 ( Kun Woo Chun ),김진학 ( Jin Hak Kim ),김민식 ( Min Sik Kim ),김민석 ( Min Seok Kim ) 한국산림과학회 2012 한국산림과학회지 Vol.101 No.1

Rainfall is widely recognized as a major landslide-triggering factor. Most of the latest landslides that occurred in South Korea were caused by short-duration heavy rainfall. However, the relationship between rainfall characteristics and landslide occurrence is poorly understood. To examine the effect of rainfall on landslide occurrence, cumulative rainfall (mm) and rainfall intensity (mm/hr) of serial rain and antecedent rainfall (mm) were analyzed for 18 landslide events that occurred in the southern and central regions of South Korea in June and July 2011. It was found that all of these landslides occurred by heavy rainfall for one or three days, with the rainfall intensity exceeding 30 mm/hr or with a cumulative rainfall of 200 mm. These plotted data are beyond the landslide warning criteria of Korea Forest Service and the critical line of landslide occurrence for Gyeongnam Province. It was also found that the time to landslide occurrence after rainfall start(T) was shortened with the increasing average rainfall intensity(ARI), showing an exponential-decay curve, and this relation can be expressed as「T = 94.569·exp (-0.068·ARI)(R2= 0.64, p<0.001)」. The findings in this study may provide important evidences for the landslide forecasting guidance service of Korea Forest Service as well as essential data for the establishment of non-structural measures such as a warning and evacuation system in the face of sediment disasters.

지역특성을 고려한 강우 앙상블 멤버 생성 기법 제안

강민석(Kang, Minseok),나우영(Na, Wooyoung),유철상(Yoo, Chulsang) 한국방재학회 2019 한국방재학회논문집 Vol.19 No.7

본 연구에서는 지역적인 특성을 고려하여 강우 앙상블 멤버를 생성하는 기법을 제안하였다. 지역특성으로는 강우의 이동방향과 강우강도의 공간적 분포를 고려하였다. 본 연구에서는 적용 사례로 지상우량계의 분포밀도가 조밀한 서울특별시에 대해 모의 격자망을 구축하고, 앙상블 기법을 적용하였다. 격자별 특성방향과 강우강도 가중치는 최근 10년 동안 발생한 주요 호우사상의 관측자료를 토대로 결정하였다. 앙상블 멤버는 특성방향의 통계치로부터 유도된 베타분포를 기반으로 생성하였다. 강우의 이동모의를 100회 수행하면 총 100개의 앙상블 멤버가 생성되고, 이 앙상블 멤버들을 단순평균한 결과가 앙상블 평균이 된다. 생성된 앙상블 멤버와 강우 앙상블 평균에 대한 평가는 강우강도 가중치를 기준으로 수행되었다. 여러 형태의 가상의 강우장을 입력하여 생성한 앙상블 멤버는 강우강도 가중치의 공간적 분포와 상당히 유사함을 확인하였다. 또한, 강우 앙상블 평균은 강우 앙상블 멤버들의 평균적인 특성을 가지는 것으로 나타났다. 이러한 결과는 2018년에 발생한 실제 호우사상을 입력한 경우에서도 확인할 수 있었다. This paper proposes a method for generating rainfall ensemble members by considering regional characteristics. The movement directions of storms (characteristic direction) and spatial distribution of rainfall intensity (rainfall-intensity weight) are considered as the regional characteristics. As a case study, grids for the ensemble simulation are set in Seoul, Korea, where the rain-gauge density is quite high. The characteristic direction and rainfall-intensity weight of each grid are determined based on observations of major storm events that occurred in Seoul during the last 10 years. The rainfall ensemble members are generated by considering the characteristic directions quantified using the beta distribution. A total of 100 rainfall ensemble members are generated by repeating the simulation of the storm movement. The result from the simple average of these ensemble members is considered as the ensemble mean. The rainfall ensemble members and ensemble mean are evaluated based on the rainfall-intensity weights. The rainfall ensemble members generated using various types of rainfall fields are found to be very similar to the spatial distribution of the rainfall-intensity weights. The ensemble mean is also found to exhibit average characteristics of the rainfall ensemble members. The same results are also derived from the simulation of the storm event that occurred in 2018.

춘천시에서 발생한 산사태 유발강우의 특성 분석

김상욱,백경오 한국안전학회 2022 한국안전학회지 Vol.37 No.6

Every year, particularly during the monsoon rainy season, landslides at the Chuncheon province of South Korea cause tremendous damage to lives, properties, and infrastructures. More so, the high rainfall intensity and long rainfall days that occurred in 2020 have increased the water content in the soil, thereby increasing the chances of landslide occurrences. Besides this, the rainfall thresholds and characteristics responsible for the initiation of landslides in this region have not been properly identified. Therefore, this paper addresses the rainfall thresholds responsible for the initiation of landslides at Chuncheon from a regional perspective. Using data obtained from rainfall measurements taken from 2002 to 2011, we identify a threshold relationship between rainfall intensity and rainfall duration for the initiation of landslides. In addition, we identify the relationship between the rainfall intensity using a 3-day, 7-day, and 10-day antecedent rainfall observation. Specifically, we estimate the rainfall data at 8 sites where debris flow occurred in 2011 by kriging. Following this, the estimated data are used to construct the relationship between the intensity (I), duration (D), and frequency (F) of rainfall. The results of the intensity-durationfrequency (IDF) analysis show that landslides will occur under a rainfall frequency below a 2-year return period at two areas in Chuncheon. These results will be effectively used to design structures that can prevent the occurrence of landslides in the future. -

Spatio-Temporal Variability of Rainfall over Bangladesh During the Time Period 1969-2003

Shamsuddin Shahid,Osman Salleh Khairulmaini 한국기상학회 2009 Asia-Pacific Journal of Atmospheric Sciences Vol.45 No.3

Spatial and temporal variability of rainfall in Bangladesh has been studied in this paper from thirty-five years (1969-2003) of rainfall data recorded at 24 rain gauges distributed over the country. Long-term annual average rainfall, coefficient of variation of annual rainfall, precipitation concentration and aridity indices at each station have been computed and then interpolated using kriging method within a geographic information system to show the temporal and spatial variability of rainfall. Mann-Kendall test has been used to analyze the trend in rainfall data in different recording stations and the Sen’s slope method has been used to determine the magnitude of change. A moderate variation in inter-annual rainfall and high variation in intra-annual rainfall in Bangladesh have been observed. Non-significant positive trend of annual, monsoon and pre-monsoon rainfall, and a negative trend in winter rainfall are found in Bangladesh. Spatial distribution of rainfall trends shows that rainfall is increasing in the coastal zone and northern Bangladesh, and decreasing in the central part of the country. A declining trend of precipitation concentration is also observed in most of the stations. These results may be a first indication of the precipitation response to global warming ? a hypothesis which needs to be further investigated by means of climate model projections.