Localized Heavy Rainfall Research Articles

HEC-RAS 모델을 이용한 신천 시험유역의 하도 특성연구

In recent localized heavy rainfalls have been arising from abnormal climate change. People are concerning about damages with increasing the frequency of flooding. Therefore, we need to understand river hydraulic characteristics and management to reduce damage from flooding. To study hydraulic characterization of Sincheon experimental catchment HEC-RAS (Hydrologic Engineering Center River Analysis System) model which provided by U.S Army Corps of Engineers (USACE) was applied. This study analyzed and compared water level the frequency flood for 100 years and 200 years by clark unit Hydrography. The change of the water level of Daejeon bridge, Sincheon bridge and Singi bridge showed increased for all conditions. The flow rate for the Daejeon bridge and the Sincheon bridge showed an increase, but the Sinki bridge showed a decreasing flow rate overally, except for 1hour-100 years. The verification result showed that the model was able to simulate the water level with 0.4709 coefficient of determination and error ration ranging from 1 to 3%.

Monitoring System for Atmospheric Water Vapor with a Ground-Based Multi-Band Radiometer: Meteorological Application of Radio Astronomy Technologies

High-resolution estimation of thermodynamic properties in the atmosphere can help to predict and mitigate meteorological disasters, such as local heavy rainfall and tornadic storms. For the purposes of short-term forecasting and nowcasting of severe storms, we propose a novel ground-based measurement system, which observes the intensity of atmospheric radiation in the microwave range. Our multi-band receiver system is designed to identify a rapid increase in water vapor before clouds are generated. At frequencies between 20 and 30 GHz, our system simultaneously measures water vapor as a broad absorption peak at 22 GHz as well as cloud liquid water. Another band at 50–60 GHz provides supplementary information from oxygen radiation to give vertical profiles of physical temperature. For the construction of this cold receiver system, novel technologies originally developed for observations of cosmic microwave background radiation were applied. The input atmospheric signal is amplified by a cold low-noise amplifier maintained below 10 K, while the spectrum of this amplified signal is measured using a signal analyzer under ambient conditions. The cryostat also contains a cold black body at 40 K to act as a calibration signal. This calibration signal is transported to each of the receivers via a wire grid. We can select either the atmospheric signal or the calibration signal by changing the orientation of this wire. Each receiver can be calibrated using this setup. Our system is designed to be compact (\(<\)1 m\(^{3}\)), with low power consumption (\(\sim \)1.5 kW). Therefore, it is easy to deploy on top of high buildings, mountains, and ship decks.

Effect of the early and late onset of summer monsoon over the Bay of Bengal on Asian precipitation in May

The impact of early and late Bay of Bengal (BoB) summer monsoon (BoBSM) onset on Asian precipitation in May is investigated. When the BoBSM occurs earlier (later), May rainfall tends to be enhanced (suppressed) in the southern Indian peninsula (SIP), the Indochinese peninsula (ICP), southwest China (SWC) and the South China Sea (SCS), while south China (SC) rainfall tends to be suppressed (enhanced). When the BoBSM occurs earlier than the climatological mean (late April), strong convective activity emerges earlier over the BoB, which causes local strong convective heating earlier. Then, earlier spread of heating in the BoB towards both sides leads to earlier retreat of the subtropical highs in the western Pacific (WPSH) and Indian Ocean outwards the BoB. Thus, compared to the climatological mean, the two subtropical highs present larger retreat outwards the BoB and smaller meridional extent over the SCS and Arabian Sea in May, which contributes to positive heating anomalies over the SCS and Arabian Sea. Therefore, anomalous cyclonic circulations occur over the BoB, SCS and Arabian Sea in May. Anomalous cyclonic circulation is favorable for low-level convergence over the SIP, and thus resulting in local heavy rainfall. Associated with cyclonic circulation anomalies over the BoB and SCS, anomalous low-level convergent winds and ascending flows favor positive precipitation anomalies in the ICP, SWC, and SCS, while anomalous northeasterlies and descending flows affected by the southward retreat of the WPSH lessen SC rainfall. In late onset years the opposite occurs.

강우장 추정을 위한 공간보간기법의 적용성 평가

In recent, the natural disaster like localized heavy rainfall due to the climate change is increasing. Therefore, it is important issue that the precise observation of rainfall and accurate spatial distribution of the rainfall for fast recovery of damaged region. Thus, researches on the use of the radar rainfall data have been performed. But there is a limitation in the estimation of spatial distribution of rainfall using rain gauge. Accordingly, this study uses the Kriging method which is a spatial interpolation method, to measure the rainfall field in Namgang river dam basin. The purpose of this study is to apply KED(Kriging with External Drift) with OK(Ordinary Kriging) and CK(Co-Kriging), generally used in Korea, to estimate rainfall field and compare each method for evaluate the applicability of each method. As a result of the quantitative assessment, the OK method using the raingauge only has 0.978 of correlation coefficient, 0.915 of slope best-fit line, and 0.957 of and shows an excellent result that MAE, RMSE, MSSE, and MRE are the closest to zero. Then KED and CK are in order of their good results. But the quantitative assessment alone has limitations in the evaluation of the methods for the precise estimation of the spatial distribution of rainfall. Thus, it is considered that there is a need to application of more sophisticated methods which can quantify the spatial distribution and this can be used to compare the similarity of rainfall field.

Asian Monsoon variation over the late Neogene–early Quaternary recorded by Anisotropy of Magnetic Susceptibility (AMS) from Chinese loess

This paper discusses the Anisotropy of Magnetic Susceptibility (AMS) records during late Neogene to early Quaternary from the Lantian loess section near the southern margin of the Chinese Loess Plateau. The AMS results for this site are shown to reflect variations in the direction of the paleomonsoon. The Lantian loess sediments are largely aeolian in origin, but also include a thin layer that exhibits secondary aqueous depositional features. The major ellipsoid axis AMS orientations in the loess samples indicate a pervasive Northwest–Southeast directional component since the late Neogene. Since that time, the W–E component gradually overtakes the N–S component, which may explain the trend toward increased aridity during that time. Finally, a local heavy rainfall event seemingly occurred in the Lantian region about 2.6 Ma, which may have been responsible for the aqueous redeposition of sediments observed in L33 layer in this study.

Meteorological Characteristics of Local Heavy Rainfall in the Fukuoka Plain

Heavy local rainfall has been increasingly observed in urban Fukuoka on fine summer afternoons in recent years. Such rainfall tends to occur suddenly on calm afternoons and is considered to be caused by local wind conditions influenced by local topography rather than by weather fronts or typhoons. This local rainfall is considered to be caused by a mechanism different from similar rainfalls occurring on fine Kanto plain afternoons. We set up 14 rain gauges in urban Fukuoka in this study to clarify and confirm actual local rainfall conditions there. Maximum local rain is about 64 km2lasting 10 to 30 minutes. The maximum 10-minute rainfall was 13.8 mm. The average surface air temperature on days with local rainfall differs 2°–3°C from that on fine days. Upper atmosphere humidity distribution differs greatly between fine days and those with heavy local rain. Accordingly, heavy local rain is more likely to occur if surface air temperature and humidity in upper atmosphere rise above a certain level. Some difference is seen between days of heavy local rainfall and fine day in terms of the K index (KI), a measure of atmospheric stability. We confirmed that the atmospheric state becomes more unstable on days with heavy local rainfall than on fine days. Heavy local rainfall often begins in either the eastern or western inland Fukuoka plain and moves toward the coast. That is, based on numerical simulation using the meteorological mesoscale weather research and forecasting (WRF) model, wind blowing opposite to the sea wind blows in the upper atmosphere, moving cumulonimbus clouds causing heavy local rainfall toward the coast. We also confirmed that heavy local rainfall tends to occur in eastern inland areas with wind from the west, but tends to occur in western areas with wind from the east. We therefore assumed that heavy local rainfall in urban Fukuoka was triggered by updrafts generated when wind struck the inland Fukuoka plain mountain system.

Improvement of rainfall and flood forecasts by blending ensemble NWP rainfall with radar prediction considering orographic rainfall

Summary Many basins in Japan are characterized by steep mountainous regions, generating orographic rainfall events. Orographic rainfall may cause localized heavy rainfall to induce flash floods and sediment disasters. However, the accuracy of radar-based rainfall prediction was not enough because of the complex geographical pattern of the mountainous areas. In order to reduce damage due to localized heavy rainfall, characteristics of orographic rainfall must be identified into a short-term rainfall prediction procedure. The accuracy of radar-based rainfall prediction performs best for very short lead time, however the accuracy of radar prediction rapidly decreases with increasing lead times. At longer lead times, higher accuracy QPFs are produced by Numerical Weather Prediction (NWP) models, which solve the dynamics and physics of the atmosphere. This study proposes hybrid blending system of ensemble information from radar-based prediction and numerical weather prediction (NWP) to improve the accuracy of rainfall and flood forecasting. First, an improved radar image extrapolation method, which is comprised of the orographic rainfall identification and the error ensemble scheme, is introduced. Then, ensemble NWP outputs are updated based on mean bias of the error fields considering error structure. Finally, the improved radar-based prediction and updated NWP rainfall considering bias correction are blended dynamically with changing weight functions, which are computed from the expected skill of each radar prediction and updated NWP rainfall. The proposed method is verified temporally and spatially through a target event and is applied to the hybrid flood forecasting for updating with 1 h intervals. The newly proposed method shows sufficient reproducibility in peak discharge value, and could reduce the width of ensemble spread, which is expressed as the uncertainty, in the flood forecasting. Our study is carried out and verified using the largest flood event by typhoon ‘Talas’ of 2011 over the two catchments, which are Futatsuno (356.1 km2) and Nanairo (182.1 km2) dam catchments of Shingu river basin (2360 km2), which is located in the Kii peninsula, Japan.

Construction and Application of Extreme Rainstorm Probability Prediction Based on Radar Echo Base Data

Based on a statistical relation betw een local Radar echo intensity base data and local heavy rainfall,to find the upstream echo areas that will move to the local raining region in next hour by the regional Lucas-Kanade optical flow method. Meanw hile to analyze the echo features at every scan surface,so that to learn the raining system stretching altitude. By analysis of the temporal and spatial characteristics of dynamic echo areas in current hour with information at scan surfaces every 10 minutes,to build the relation betw een Radar echo intensity features and local rainfall,then applied it on a predicting method of improved rainfall extreme probability,thus to construct forecast and warning index of extreme rainfall return period in next hour. The results will provide the technique support and professional reference for emergency schemes and strategy and tactics. The whole scheme is based on the Doppler radar echo intensity base data at scanning surfaces and the hourly precipitation data of Jianhu weather station during June,July,August in 2006-2011. Jianhu station is within the scanning area of the radar located at Yancheng. The echo dynamic upstream of the local heavy rainfall system is determined by the regional Lucas-Kanade optical flow method. The statistical probability correlation is calculated betw een echo intensity classification and precipitation series in day and night by Peirson III and Generalized Pareto Distribution methods. The probability characteristics of return period of graded extreme rainfall and the local extreme rainfall under the echo types are also calculated,then the statistic index is constructed betw een the radar echo dynamic features including the trend of evolution and the probability of local extreme rainfall in next hour,the index correlation and its test all get to 70%. The index can predict the probabilities of different grade extreme rainfall in return period at local place. It is an optimization method of radar dynamic statistics for now casting and warning of the extreme rainstorm in next hour.

무선 데이터 방송을 이용한 국지성 폭우 예보 서비스 프레임워크의 설계와 구현

무선 데이터 방송을 이용한 국지성 폭우 예보 서비스 프레임워크의 설계와 구현

Event Based Flood Inundation Mapping Under the Impact of Climate Change: A Case Study in Lower Kelani River Basin, Sri Lanka

The downstream low lying region of the Kelani River including the Colombo suburbs, experience severe inundation due to localized heavy rainfall events and high precipitation in the upper basin. Under the impact of climate change it is very likely that more frequent heavy rainfalls in tropics [1] will occur. Therefore it is extremely important to have a better understanding about future rainfall patterns and intensities in the basin and inundation extents of the low lying regions characterized by high population concentration and economic activities that form the suburbs of the commercial capital. This paper presents the extreme rainfalls occurrence potential and resulting flood inundation along the lower reach of Kelani River. Coarse grid atmospheric parameters provided by GCM models for A2 and B2 scenarios of IPCC [1] are downscaled to catchment scale by the application of Statistical Downscaling Model (SDSM). Flood discharge and inundation along the Kelani River reach below Hanwella was analyzed by the application of two-dimensional flood simulation model (FLO-2D). Inflow to the model at Hanwella, is estimated by the HEC- HMS model under future extreme rainfall events. Areas vulnerable for inundation under the above climate change scenarios are presented.

우수관로 경사 조정에 따른 토사 퇴적 특성 분석

관거 내에 퇴적된 토사로 인한 통수능 저감은 도심지 국지성 집중호우에 대한 내수침수의 위험성을 증가시키게 되므로 이에 대한 고려가 관거의 설계 및 유지관리상에서 이루어져야 한다. 그러나 현행 국내 우수관거 설계에 있어서 관거 내의 토사 퇴적에 대한 고려 및 이에 대한 연구는 매우 미흡한 상태이며, 따라서 이에 대한 향후 연구 및 설계기준 마련이 시급한 실정이다. 본 연구에서는 우수관거에서의 토사 퇴적을 저감하고 원활한 통수능 확보를 위하여 설계시 고려되어야 할 사항들에 대하여 검토해보았다. 이를 위해 가상의 관망에 대한 경사 조정을 통하여 토사 입경별 관거 내 퇴적 양상을 분석하였다. 또한 실제 도심지 우수관망에서의 관거 설계 변경에 따른 토사 퇴적 양상을 분석하기 위하여, 부산시 부전천 유역에 대하여 현재의 우수관로를 임의로 경사를 조정함으로써 관거 내 토사의 퇴적량을 저감시키고자 하였다. 분석 결과 부전천 유역의 우수관로에 대한 구간 경사 조정을 통하여 관로 내 토사의 퇴적 총량이 약 30%이상 감소될 수 있는 것으로 나타났다. 다만 퇴사량 총량과는 별도로 개개 관거의 토사 퇴적 깊이가 다양한 증감 양상을 나타냄으로 관로 전체의 안정성 측면에서는 토사의 퇴적량 및 퇴적 깊이를 동시에 고려할 수 있는 신뢰도 함수의 산정과 이에 따른 관로 설계가 중요한 것으로 나타났다. Reduction of discharge capacity due to sedimentation in sewer increase danger of the inundation risk because of occurrence of frequent localized heavy rainfall, we need to find the fundamental solution for sewer design and maintenance. However, internal researches considering sedimentation in sewer designs are very insufficient, should be urgently required by considering the characteristics about future research and design standards. In this study, examines the design concept for discharge capacity and reduction of sedimentation in sewer networks. The virtual sewer networks are designed to analysis and distribute the sedimentation of depositional patterns in the sewer conduits, while considering the sedimentation diameter, in order to reduce the inundation risk. Accordingly, to analyze detailed changes in conduit designs in urban sewer networks, tried to reduction of sedimentation in sewer networks using modified pipe slope in Bujeon stream catchment, Busan. The various sewer designs were applied to Bujeon stream catchment and then, the most effective reduction of sedimentation volume over 30%. Just, total sedimentation depth separately intended the variation cases contrary to total sedimentation volume, we need to consider about entirely adequate aspect of related to design safety. So, including both the volume and the depth consideration through estimating the reliability of sewer network systems.

유역단위 우수유출저감대책의 침수피해 저감효과 비교분석

본 연구는 도시지역 내 유역단위에서 우수유출저감시설의 효과를 비교 분석한다. 이를 위해 배수시설(하수관거), 저류시설, 침투시설로 구성된 총 3가지 대책시나리오를 구성하였으며, 각 시나리오별로 유출-범람모의를 수행하였다. 각 대안별 소요비용을 산정하여 침수피해 저감효과와 비교하였다. 그 결과, 유역단위에서 저류시설과 침투시설의 유출저감효과는 상대적으로 크진 않지만, 침수피해 저감을 목적으로 한 우수유출저감시설의 설치는 하수관거에 대한 보완적 수단으로써 효과적일 수 있음을 확인하였다. 또한 강우규모가 커질수록 하수관거 대안의 경제성은 상대적으로 감소하고, 우수유출저감시설의 경제성은 크게 증가함을 알 수 있었다. 이는 설계기준을 초과하는 집중호우에의 탄력적 대응을 위해 우수유출저감시설의 확대 운영이 필요함을 시사한다. The purpose of this study is to evaluate the flood reduction effects of stormwater storage and infiltration facilities at a urban catchment scale and to compare the cost-effectiveness with drainage system improvements. Three policy scenarios to mitigate flood damage were developed by considering drainage system improvements, storage installations, and infiltration facility installations. The installation costs and flood reduction effects of the scenarios were compared to each other. The result shows that, while the stormwater storage and infiltration facilities were marginally effective in reducing the amount of peak flow and runoff volume, they were more effective in reducing the inundation damage. As rainfall increases, the cost-effectiveness of drainage improvements measures decreases relatively, yet the cost-effectiveness of stormwater storage and infiltration facility measures increases remarkably. This result indicates that stormwater storage and infiltration facilities could be helpful to mitigate urban flood risk more fundamentally as local heavy rainfall increases.

여름철 한반도 강수의 시·공간적 특성 연구

This study investigated the temporal and spatial characteristics of summertime (June-August) precipitation over Korean peninsula, using Korea Meteorological Administration (KMA)is Automated Synoptic Observing System (ASOS) data for the period of 1973-2010 and Automatic Weather System (AWS) data for the period of 1998-2010.The authors looked through climatological features of the summertime precipitation, then examined the degree of locality of the precipitation, and probable precipitation amount and its return period of 100 years (i.e., an extreme precipitation event). The amount of monthly total precipitation showed increasing trends for all the summer months during the investigated 38-year period. In particular, the increasing trends were more significant for the months of July and August. The increasing trend of July was seen to be more attributable to the increase of precipitation intensity than that of frequency, while the increasing trend of August was seen to be played more importantly by the increase of the precipitation frequency. The e-folding distance, which is calculated using the correlation of the precipitation at the reference station with those at all other stations, revealed that it is August that has the highest locality of hourly precipitation, indicating higher potential of localized heavy rainfall in August compared to other summer months. More localized precipitation was observed over the western parts of the Korean peninsula where terrain is relatively smooth. Using the 38-years long series of maximum daily and hourly precipitation as input for FARD2006 (Frequency Analysis of Rainfall Data Program 2006), it was revealed that precipitation events with either 360 mm <TEX>$day^{-1}$</TEX> or 80 mm <TEX>$h^{-1}$</TEX> can occur with the return period of 100 years over the Korean Peninsula.

A Comparison of Two Heavy Rainfall Events during the Terrain-Influenced Monsoon Rainfall Experiment (TiMREX) 2008

Abstract Two contrasting localized heavy rainfall events during Taiwan’s early summer rainy season with the daily rainfall maximum along the windward mountain range and coast were studied and compared using a combination of observations and numerical simulations. Both events occurred under favorable large-scale settings including the existence of a moisture tongue from the tropics. For the 31 May case, heavy rainfall occurred in the afternoon hours over the southwestern windward slopes after a shallow surface front passed central Taiwan. The orographic lifting of the prevailing warm, moist, west-southwesterly flow aloft, combined with a sea breeze–upslope flow at the surface provided the localized lifting needed for the development of heavy precipitation. On 16 June before sunrise, pronounced orographic blocking of the warm, moist, south-southwesterly flow occurred because of the presence of relatively cold air at low levels as a result of nocturnal and rain evaporative cooling. As a result, convective systems intensified as they moved toward the southwestern coast. During the daytime, the cold pool remained over southwestern Taiwan without the development of onshore/upslope flow. Furthermore, with a south-southwesterly flow aloft parallel to terrain contours, orographic lifting aloft was absent and preexisting rain cells offshore diminished after they moved inland. Over northern Taiwan on the lee side, a sea breeze/onshore flow developed in the afternoon hours, resulting in heavy thundershowers. These results demonstrate the importance of diurnal and local effects on determining the location and timing of the occurrences of localized heavy precipitation during the early summer rainy season over Taiwan.

내수침수시나리오와 침수피해곡선을 활용한 도시지역 내수침수피해특성 분석

최근 우리나라에서는 기후변화에 의한 집중호우의 영향으로 여름철마다 내배수 시설물의 설계빈도를 벗어나는 강우사상이 빈번하게 발생하고 있다. 특히 불투수성이 큰 도시지역의 경우에는 우수관거 및 펌프장에 대한 의존도가 높아 극치강우로 인한 내수침수의 발생 및 그 피해가 증가하고 있다. 본 연구에서는 내수침수 위험도가 높은 지역의 내수침수피해 특성을 분석할 수 있는 방법을 제시하였다. 부산시 연제구 거제지구를 대상으로 다양한 지속시간과 강우강도를 고려한 강우시나리오를 구축하였으며, XP-SWMM을 활용하여 내수침수시나리오를 구축하였다. 본 연구에서는 다차원법을 바탕으로 만들어진 내수침수피해액 산정법을 활용하여, 침수심과 침수면적에 따른 침수피해액을 산정한 후, 내수침수시나리오에 따른 침수피해곡선을 작성하였다. 또한 이를 바탕으로 대상지역의 내수침수피해 특성을 분석하였다. 본 연구를 통하여 침수가 발생하기 시작하는 강우량 및 큰 침수피해를 유발하는 호우사상을 파악하며, 침수가 발생되는 지역의 침수면적, 침수심, 침수피해액을 예측하는 수단으로 활용할 수 있을 것이다. Recently, in Korea, localized heavy rainfall events have occurred frequently due to climate change. Especially, since urban areas depend heavily on pump and pipe systems, extreme rainfalls that exceed the design capacity of drainage facility result in increasing inland flood damage. This study proposed a methodology to analyze urban flood damage characteristics in inland flood prone areas. After firstly constructing rainfall scenarios which have various durations and intensities, inland flood scenarios were developed using XP-SWMM. This study presented the inland flood damage analysis (IFDA) to calculate inland flood damage from the inland flood scenarios. Based on the inland flood scenarios and corresponding flood damage curves, the characteristics of damage due to inland flood were analyzed using the relationships among precipitation depth, flood depth, and flood area. The proposed method can be used to identify the storm event resulting in heavy flood damage, and to predict the flood area, depth and damage from various storm events.

A comparison between the effects of artificial land cover and anthropogenic heat on a localized heavy rain event in 2008 in Zoshigaya, Tokyo, Japan

AbstractOn 5 August 2008, a localized heavy rainfall event caused a rapid increase in drainpipe discharge, which killed five people working in a drainpipe near Zoshigaya, Tokyo. This study compared the effects of artificial land cover and anthropogenic heat on this localized heavy rainfall event based on three ensemble experiments using a cloud‐resolving model that includes realistic urban features. The first experiment CTRL (control) considered realistic land cover and urban features, including artificial land cover, anthropogenic heat, and urban geometry. In the second experiment NOAH (no anthropogenic heat), anthropogenic heat was ignored. In the third experiment NOLC (no land cover), urban heating from artificial land cover was reduced by keeping the urban geometry but with roofs, walls, and roads of artificial land cover replaced by shallow water. The results indicated that both anthropogenic heat and artificial land cover increased the amount of precipitation and that the effect of artificial land cover was larger than that of anthropogenic heat. However, in the middle stage of the precipitation event, the difference between the two effects became small. Weak surface heating in NOAH and NOLC reduced the near‐surface air temperature and weakened the convergence of horizontal wind and updraft over the urban areas, resulting in a reduced rainfall amount compared with that in CTRL.

SWMM-LID를 이용한 상습침수유역 내 유출저감효과 분석

최근 기후변화에 의한 기상현상은 국지성 집중호우, 돌발홍수 등을 발생시켜 많은 인명과 재산의 피해를 가져오고 있다. 이로 인해 기록적인 폭우의 발생이 증가되고 있으며, 도시개발로 인해 자연공간이 감소하여 개발 전 지표면이 가지고 있던 유역 내 저류 및 지연효과가 현저하게 감소하고 시가지의 확대와 도로포장 등 유역 내 불투수층의 증가로 인하여 홍수유출량과 첨두유량이 점차 증가되고 있다. 이와 같은 원인으로 유출 출구점까지의 도달시간은 자연유역에 비해 현격하게 짧아져 과거 자연하천 유역과는 다른 수문학적 특성을 가지게 되며, 도시집중 현상으로 택지 및 시설부지의 부족현상이 가중됨으로써 하천범람 구역이나 홍수우려가 있는 범람원내 저지대까지 도시화가 이루어짐으로써 치수상 안전도가 상대적으로 저하되고 있다. 이에 본 연구에서는 도시유출해석모형인 SWMM 내 LID 모듈을 이용하여 대상유역내 적용 가능한 LID 기법 기술요소를 분석하여 적용하고 LID 기법에 따른 유출저감효과를 분석하였다. 분석결과, LID 영향 분석 시나리오는 각 기법의 적용에 따른 영향과 LID 적용전, 옥상녹화적용, 투수성포장의 적용 등 LID 3개의 시나리오를 선정하여 적용하였다. 시나리오 적용결과, 시나리오 A에 비하여 시나리오 B는 288.52ton, 시나리오 C는 240.26ton이 저감되었으며 각각 15.62%, 13.01%의 유출량 저감효과를 보였다. Recently meteorological phenomena caused by climate change have brought localized heavy rainfalls, flash-floods causing severe damage for human-life and property. They also increase the occurrence of record-breaking rainfall. Development in urban area decreases the portion of open spaces, landscapes, leading to significant diminution of storage and detention function of the basin. The expansion of impervious areas increases the extent of peak-runoff and runoff volume, especially the shorter time of concentraion due to development makes the basin have different hydrological characteristics compared to pre-development. In addition, urbanization worsen the requirement of site for residence and public facility so that even floodplain and inundated district are urbanized threatening safety for flood control. In this study, applicable LID techniques are analyzed and implemented using LID modules of SWMM, which is the model for urban stormwater-runoff management in the project area. Effects of implementing LID practices are also assessed and reviewed. The result shows that scenario B and C ruduced 288.52ton(15.62%), 240.26ton(13.01%) each in runoff simulations compared to scenario A.

2010년 9월 21일 추석 호우와 관련된 대류 세포의 위성 영상 분석

이 연구에서는 MTSAT-2 적외 영상과 수증기 영상을 이용하여 2010년 9월 21일 추석 호우 사례에 대하여 대류운 생애주기의 각 단계에서 나타나는 특징을 조사하였다. 추석 호우와 관련된 최초의 구름은 20일 1630~1900 UTC에 서해 중부 지역에서 관측된 다중 세포의 하층운이다. 이 구름 가운데 일부가 1930 UTC에 산동반도 부근에서 휘도온도 <TEX>$-45^{\circ}C$</TEX> 이하의 대류 세포로 발달한다. 이 때 이 지역은 수증기 영상에서 암역의 가장자리에 위치한다. 대류 세포는 동진하다가 한반도 중서부 해안 부근에서 21일 0030과 0430 UTC에 두 차례의 병합을 거쳐 급격히 발달한다. 이후 21일 0430에서 1000 UTC까지 약 6시간 동안 위성 영상에서 구름의 면적은 상대적으로 작고, 수평 이동속도는 느려졌다. 최저 휘도온도는 약 <TEX>$-75{\sim}-65^{\circ}C$</TEX>로 매우 낮게 유지되며, 잘 발달한 부세포가 반복적으로 형성되는 특징을 보인다. 레이더 자료에는 국지적으로 50 mm/hr 이상의 강우율을 보이는 좁은 띠 모양의 강우 밴드가 나타나고 이 밴드는 대류운의 남서쪽 가장자리에 위치한다. 그러나 수치 모델 자료의 종관 규모 역학적 강제항에는 뚜렷한 특징을 찾기 어렵다. 대류 세포의 구름 면적은 21일 1000 UTC 이후 짧은 시간에 급격한 증가를 보이고 뒤이어 소멸한다. 이러한 대류 세포의 발달과 관련된 위성 영상의 특징은 중규모 호우의 초단기 예보와 실시간 예보에 사용될 수 있을 것이다. On 21 September 2010, one of Chuseok holidays in Korea, localized heavy rainfalls occurred over the midwestern region of the Korean peninsula. In this study MTSAT-2 infrared and water vapor channel imagery are examined to find out some features which are obvious in each stage of the life cycle of convective cell for this heavy rain event. Also the kinematic and thermodynamic features probably associated with them are investigated. The first clouds related with the Chuseok heavy rain are detected as low-level multicell cloud (brightness temperature: <TEX>$-15{\sim}0^{\circ}C$</TEX>) in the middle of the Yellow sea at 1630~1900 UTC on 20 Sept., which are probably associated with the convergence at 1000 hPa. Convective cells are initiated in the vicinity of Shantung peninsula at 1933 UTC 20, which have developed around the edge of the dark region in water vapor images. At two times of 0033 and 0433 UTC 21 the merging of two convective cells happens near midwestern coast of the peninsula and then they have developed rapidly. From 0430 to 1000 UTC 21, key features of convective cell include repeated formation of secondary cell, slow horizontal cloud motion, persistence of lower brightness temperature (<TEX>$-75{\sim}-65^{\circ}C$</TEX>), and relatively small cloud size (<TEX>${\leq}-50^{\circ}C$</TEX>) of about <TEX>$30,000km^2$</TEX>. Radar analysis showed that this heavy rain is featured by a narrow line-shaped rainband with locally heavy rainrate (<TEX>${\geq}50$</TEX> mm/hr), which is located in the south-western edge of the convective cell. However there are no distinct features in the associated synoptic-scale dynamic forcing. After 1000 UTC 21 the convective cell grows up quickly in cloud size and then is dissipated. These satellite features may be employed for very short range forecast and nowcasting of mesoscale heavy rain system.

Use of ensemble simulations to evaluate the urban effect on a localized heavy rainfall event in Tokyo, Japan

Recently, localized heavy rainfall over highly urbanized areas has caused severe damage in Japan. Although studies have indicated that the presence of urban areas can intensify rainfall, the chaotic noise caused by differences in initial conditions can change the urban effect. Therefore, the usability of ensemble simulation methods for urban effects on a single localized heavy rainfall event must be clarified to synthesize state-of-the-art observations and numerical model studies. This study examined the difference in a localized heavy rainfall event under different initial conditions. We demonstrated the advantage of ensemble experiments using a cloud-resolving model to evaluate the urban effect. In this study, we focused on a localized heavy rainfall event that occurred over Tokyo on 5 August 2008 and killed five people working in a drainpipe. Two ensemble experiments were performed according to the lagged average forecasting (LAF) method. Each experiment had six members, with initial conditions spanning 6 h from 02 to 07 Local Standard Time (LST) on 5 August 2008. The model was integrated continuously through 18 LST for each run. The model had a horizontal grid resolution of 2 km. The first experiment (CTRL) used the actual land cover, anthropogenic heat, and geometric structures. The second experiment (PDDY) used an imaginary land cover in which the urban area was changed to paddy fields. Comparison of the ensemble means showed that the peak value of the maximum hourly rainfall decreased and the peak time was delayed in PDDY compared with CTRL. The smaller peak value and delayed peak time of rainfall in PDDY seemed to be caused by the weaker updraft associated with near-surface convergence, which was caused by weaker surface heating. Regardless of the difference caused by the initial conditions, the decrease in the peak value and the delay in the peak time were significant according to the t-test. Although the area was limited compared with near-surface temperature and horizontal wind convergence, a significant reduction in rainfall was also seen over the heavily urbanized area of Tokyo in the horizontal distribution of the difference in accumulated rainfall. These results indicate that although differences in the initial condition can change the modeled urban effect on rainfall, ensemble simulation methods can be used to examine the significance of the urban effect on a single localized heavy rainfall event.

기후변화 시나리오(RCP)를 이용한 도시지역 빗물펌프장의 미래 필요용량 산정

최근 기상이변의 증가로 인해 돌발성 집중호우가 빈번하게 발생하고 있다. 기상청에서는 이런 기후변화에 대비하기 위하여 최근 온실가스 증가경향을 반영한 새로운 온실가스 시나리오를 제시하였다. 따라서 본 연구에서는 새로운 온실가스 시나리오인 RCP 시나리오를 이용하여 인천광역시의 미래기간에 대한 목표기간별 확률강우량의 변화를 추정하였다. 이를 토대로 미래에 증가되는 빗물펌프장 용량을 추정하여 현 시설물의 필요(수요)용량을 산정하였다. 최악의 시나리오인 RCP 8.5에 따르면, 대상지역인 인천광역시의 9개 빗물펌프장 중 3개소는 미래 강우의 증가에도 어려움이 없을 것으로 판단되나, 나머지 6개 펌프장의 시설용량은 미래 강우를 수용하기에 부족한 것으로 나타났다. 특히, 목표기간III(2071-2100) 강우를 수용하기 위해선 현재 시설용량을 6배정도 증설해야할 것으로 예상되었다. 따라서 본 연구를 통해 도출된 결과를 토대로 인천지역의 미래 도시배수시스템의 용량을 검토하여 대비할 필요가 있을 것으로 판단된다. In the recent years, flash flood and local heavy rainfall have been frequently occurred in Korea and this may be due to the climate change. Korea Meteorological Administration(KMA) and IPCC AR5 reported new greenhouse gas scenario called RCPs(Representative concentration pathways). This study tries to analyze the variability and trend of future rainfall using the new RCP scenarios. Based on this, we estimate the needed capacity(demand) at existing pumping station for the future. The study area is Incheon-city, Korea which has 9 pumping stations. This study uses the RCP 8.5 which is the worst scenario of RCPs for the impact assessment of climate change and there will be no difficulty in the three of nine pumping stations for the future rainfall. But, the capacities of 6 pumping stations will not be sufficient for the future rainfall and runoff. It is expected to construct more pumping stations allowable 6 times of existing pump capacity especially for Target III(2071-2100). Therefore, we may need to prepare for the future flood damage potential by reviewing the capacity of future drainage system in Incheon city.