• Journal of Environmental Impact Assessment
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• v.20 no.2
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• pp.227-234
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• 2011

In the study, CE-QUAL-W2 was used and its examination and correction were conducted targeting 2001 and 2003 when the condition of rainfall was contradicted. Using the proved model in 2003, a scenario was implemented with management of locations for dewatering outlets and actual data for dam management in 1987 when inflow and outflow level were almost same. In case of the scenario which the location of dewatering outlets was 5m higher than usual location, exclusion efficiency for turbid water inflow at the beginning of precipitation was good. In case of the scenario which the location of dewatering outlets was 10m lower than usual location, exclusion efficiency for excluding turbid water remained in a reservoir after the end of precipitation. However, the scenario applying dam management data in 1987, exclusion efficiency was relatively low. In the scenario, power-generating water release spot at EL.57m for first four days after the beginning of precipitation, EL.52m for 5th to 8th and EL.42m from 9th days. An analysis of the scenario reveals that both excessive days exceeded 30 NTU and average turbidity levels were decreased comparing before and after the alteration on outlets. The average turbidity levels were decreased by minimum of 55% to maximum of 70% and 30NTU exceeding days were decreased by 45 days at maximum. Also, since it could exclude most of turbid water in a reservoir before the destatifcation, the risk for turbid water evenly distributed in a reservoir along with turn-over could be decreased as well.

• Journal of Korean Society on Water Environment
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• v.22 no.1
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• pp.128-133
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• 2006

The paved areas in nonpoint source are highly polluted landuses because of high imperviousness and high pollutant mass emissions from vehicle activities. Particularly, the metal pollutants are a big issue in the paved area. It is usually washed-off during storms by adsorbing on sediments or soluble status. Therefore, this research was achieved for understanding the characteristics of metal pollutants in stormwater runoff in highways. Five monitoring sites were equipped with an automatic rainfall gage and an automatic flow meter. This manuscripts will summarize the washoff characteristics of metal pollutants and its concentration changes during storms. Usually first flush phenomenon was observed for all of the storm events and visibly confirmed with hydro- and polluto-graphs. Also it was coincided with the tendency of particulates and organic matters. The decrease rate per total reduced amount for metals during initial 30-min storm duration was obtained on 80%. The result may be able to use for determining the economical treatment criteria for stormwater runoff in highways.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.1
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• pp.37-45
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• 2015

Recent droughts in South Korea have had large economic and environmental impacts across the country. Changes in rainfall and hydrologic patterns due to climate change can potentially increase the occurrence of extreme droughts and affect the future availability of water resources. Therefore, it is necessary to evaluate drought vulnerability for water resources planning and management, and identify the appropriate mitigation actions to conduct a drought risk analysis in the context of climate change. The objective of this study is changes in the temporal trends of drought characteristics in South Korea to examine drought impacts under climate change. First, the changes of drought occurrence were analyzed by applying the Standardized Precipitation Evapotranspiration Index (SPEI) for meteorological data on 54 meteorological stations, and were analyzed for the past 30 years (1981-2010), and Representative Concentration Pathways (RCP) climate change scenarios (2011-2100). Second, the changes on the temporal trends of drought characteristics were performed using run theory, which was used to compare drought duration, severity, and magnitude to allow for quantitative evaluations under past and future climate conditions. These results show the high influence of climate change on drought phenomenon, and will contribute to water resources management and drought countermeasures to climate change.

• Journal of Environmental Science International
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• v.19 no.1
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• pp.115-124
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• 2010

Urban watershed can be found in the visible changes in technology, the most realistic satellite images is to use the data. Satellite image data on the indicators for progress on the nature of the change of land use is consistent and repetitive information, regular observation makes possible the detailed analysis of space-time. These remote sensing techniques and the type of course and, by using the time series history, the past, the dynamic model and the randomized prediction methodology for the conversion process if the city and river basin cooperation of the space changes effectively will be able to extrapolate. For each of the main changes in river flow, depending on the area of urbanization as determined according to reproduce the duration of the relationship between the urbanization of the area and runoff can be represented as a linear polynomial expression was, if a linear expression in the two fast slew rate of 0.858 to 0.861 showed up, and fast slew rate of 0.934 to 0.974 for the polynomial are reported. Change of land use changes in the watershed of the flow is one of the most affecting elements. Therefore, changes in land use of the correct classification of rivers is a more accurate calculation of the amount of the floodgate. In particular, using the Landsat images through the image of the land use category, land use past data and calculated using the Markov Chain model and predict the future land use plan in the water control project will be used for large likely.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.1
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• pp.231-238
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• 2017

Water supply safety index plays an important role on assessing the water supply capacity of hydrologic system. Due to the absence of consistent guidance, however, practical problems have been brought up on data period used for dam design and performance evaluation. Therefore, this study employed bivariate drought frequency analysis which is able to consider drought severity and duration simultaneously, in order to evaluate water supply capacity of multi-purpose dams. Drought characteristics were analyzed based on the probabilistic approach, and water supply capacity of five multi-purpose dams in Korea (Soyang River, Chungju, Andong, Daecheong, Seomjin River) were evaluated under the specific drought conditions. As a result, it would be possible to have stable water supply with their own inflow during summer and fall, whereas water shortage would occur even under the 1-year return period drought event during spring and winter due to low rainfall.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1434-1438
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• 2010

수문자료의 계절성은 수자원관리의 관점에서 매우 중요한 요소로서 계절성의 변동은 댐의 운영, 홍수조절, 관계용수 관리 등 다양한 분야와 밀접한 관계를 가지고 있다. 그러나 지금까지의 수문 자료의 계절성 평가는 주로 이수과점에서 이루어지고 있으며 치수관점에서 극치수문량의 계절성을 평가하는 연구는 미진한 실정이다. 이는 극치수문량을 해석하는 방법론으로서 연최대치계열(annual maxima) 즉, Block Maxima가 이용됨에 따라 나타나는 문제점이다. 그러나 부분기간치계열(partial duration series)을 활용하게 되면 자료의 확충뿐만 아니라 자연적으로 극치수문량의 계절성에 대한 평가 또한 가능하다. 이러한 분석과정을 POT(peak over threshold)분석이라 하며 일정 기준값(threshold) 이상의 자료를 모두 취하여 빈도해석에 이용하는 방법으로서 기존 방법의 경우 연최대값이 일반적으로 7월과 8월에만 존재하게 되지만 POT 분석의 경우 여러 달에 걸쳐 빈도해석을 위한 자료가 구성되게 된다. 이를 빈도해석으로 연계시키기 위해서는 계절성을 비정상성으로 고려하여 모형화 할 수 있는 방법론의 개발이 필요하다. 본 연구에서는 이러한 목적을 위해서 계절성을 고려할 수 있는 비정상성빈도해석 기법의 개념을 제시하고 모형으로 개발하고자 한다. GEV 또는 Gumbel 분포의 매개변수와 계절성을 연계시키기 위해서 Fourier 급수가 활용되며 매개변수는 Bayesian 기법을 통해 최적화 된다. 이를 통하여 설계강수량의 계절적 분포를 정량적으로 해석할 수 있으며 미래의 극치강수량에 대한 분포특성 또한 확률적으로 해석이 가능하다. 본 연구에서 제안된 방법은 국내외 시간강수량자료에 적용되어 적합성과 적용성이 평가된다.

• Journal of Korean Society on Water Environment
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• v.23 no.4
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• pp.490-497
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• 2007

A Combined sewer overflows (CSOs) are themselves a significant source of water pollution. Therefore, the control of urban drainage for CSOs reduction and receiving water quality protection is needed. Examples in combined sewer systems include downstream storage facilities that detain runoff during periods of high flow and allow the detained water to be conveyed by an interceptor sewer to a centralized treatment plant during periods of low flow. The design of such facilities as stormwater detention storage is highly dependant on the temporal variability of storage capacity available (which is influenced by the duration of interevent dry periods) as well as the infiltration capacity of soil and recovery of depression storage. As a result, a continuous approach is required to adequately size such facilities. This study for the continuous long-term analysis of urban drainage system used analytical probabilistic model based on derived probability distribution theory. As an alternative to the modeling of urban drainage system for planning or screening level analysis of runoff control alternatives, this model have evolved that offer much ease and flexibility in terms of computation while considering long-term meteorology. This study presented rainfall and runoff characteristics of the subject area using analytical probabilistic model. This study presented the average annual COSs and number of COSs when the interceptor capacity is in the range $3{\times}DWF$ (dry weather flow). Also, calculated the average annual mass of pollutant lost in CSOs using Event Mean Concentration. Finally, this study presented a decision of storage volume for CSOs reduction and water quality protection.

• Journal of agriculture & life science
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• v.45 no.4
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• pp.29-35
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• 2011

A forest fire was one of the huge disasters and damaged human lifes and a properties. Therefore, many countries operated forest fire forecasting systems which developed from forest fire records, weather data, fuel models and etc. And many countries also estimated future state of forest fire using a long-term climate forecasting like GCMs and prepared resources for future huge disasters. In this study, we analyzed relationships between forest fire occurrence and meteorological factors (the minimum temperature ($^{\circ}C$), the relative humidity (%), the precipitation (mm), the duration of sunshine (hour) and etc.) for developing a estimating tools, which could forecast forest fire regime under future climate change condition. Results showed that forest fires in this area were mainly occurred when the maximum temperature was $10{\sim}200^{\circ}C$, when the relative humidity was 40~60%, and when the average wind speed was under 2m/s. And forest fires mainly occurred at 2~3 day after rainfall.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.139-139
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• 2016

가능최대홍수량(Probable Maximum Flood, PMF)이란 대규모 수공구조물을 설계하고자 할 때 막대한 경제적 손실 및 인명피해 등을 막기 위해 기준으로 삼는 설계홍수량이며, 통계학적으로는 약 10,000년 빈도에 해당된다. 우리나라의 호우 특성은 방위, 진행방향 및 위에 따른 해석이 매우 복잡하여 강우를 정형화하기 어렵다. Kim and Won(2004)은 이동성 호우의 경우 강우의 깊이-면적-지속기간(Rainfall Depth-Area-Duration)의 분석결과에서 상당한 오차를 야기하는 문제점을 지닌다고 주장하였다. 따라서 오차를 포함한 DAD의 산정결과는 가능최대강수량(Probable Maximum Precipitation, PMP) 및 가능최대홍수량 산정에도 영향을 미치기 때문에 정확도 높은 DAD 분석을 통한 PMF 산정이 요구된다. 본 연구에서는 유역을 선정하고 각 지점의 시계열 강우 자료를 활용하여 공간분포화한 강우자료에 격자기반의 자동 강우장 탐색기법을 이용하여 DAD 분석을 실시하였다. 기존의 PMP 산정방법에서는 한반도 전역에서 발생했던 130 mm이상의 호우사상을 선정한 후에 각 호우의 범위에 있는 우량관측소의 강우자료를 이용하여 PMP를 산정한다. 그렇기 때문에 만약 상대적으로 긴 지속기간의 경우 호우의 범위가 우리나라 전역을 포함할 가능성이 크기 때문에 PMP 산정방법은 복잡하고, 기상이변이 잦지 않는 지역에서 산정된 PMP를 이용하여 PMF를 산정할 경우, 유역의 특성을 반영하지 않았기 때문에 과대산정의 우려가 있다. 이에 따라 본 연구에서는 먼저 연구대상유역을 선정한 뒤, 유역 내에 발생했던 호우경보와 호우주의보를 기준으로 호우사상을 선정하여 DAD 분석 후 PMP를 산정하였다. 그 후, 강우-유출관계를 파악하여 PMF를 산정하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.17-17
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• 2019

IPCC (Intergovernmental Panel on Climate Change) 기후변화 전망보고서에 따르면 RCP 4.5 시나리오 기준, 21세기 전 지구 평균기온은 $2.5^{\circ}C$ 상승(한반도 $+3.0^{\circ}C$)하며, 전 지구 평균강수량은 4.1% 증가(한반도 +16.0%)할 것이라 전망하고 있다(기상청, 2012). 최근 기후변화와 기상이변에 따른 도심지 폭우특성이 변화하고 있음을 많은 연구결과에서 말해주고 있으며, 그 발생 빈도와 강도가 점차 증가하고 있는 추세이다. 특히, 서울시의 경우 인구와 재산이 밀집해 있어 폭우 발생에 의한 시민의 인명과 재산 피해 우려가 크다. 따라서 본 연구에서는 서울시를 대상으로 근미래(~2050년) 기후변화 하에서의 재현기간에 따른 확률강우량 변화 특성을 분석하여 비교 평가한 후 설계 강우량 산정에 활용하고자 하였다. 관측자료 기반 강수량의 변동 특성 분석과 Non-stationary GEV방법을 이용한 비정상성 빈도해석을 수행하였으며, 근미래 폭우특성 변화분석을 위하여 CMIP5 (Coupled Model Intercomparison Project 5)에 참여한 GCMs(General Circulation Models)을 활용한 강우빈도해석을 수행하였다. Mann-Kendall Test와 Quantile Regression을 통한 서울지점 여름철 강수량(June to September)과 기준강수량 초과 강수(30, 50, 80, 100mm/hr), 연간 10th 최대 강수량(Annual Top 10th Precipitation) 등을 분석한 결과 최근 증가 경향이 뚜렷하게 나타났으며, 비정상성 빈도해석에 의한 확률강우량 분석의 가능성과 신뢰성을 확인하였다. 또한 19-GCMs을 통하여 모의된 일(Daily) 단위 강수량자료를 비모수통계적 상세화(Nonparametric Temporal Downscaling) 기법을 적용하여 시간(Hourly) 강우로 다운스케일링하였으며, 서울시 미래 확률강우량에 대한 IDF 곡선(Intensity-Duration-Frequency Curve)을 작성하여 비교?분석한 결과 지속시간 1시간 강우에 대하여 재현기간 30년, 100년 조건에서 확률강우량이 약 4%~11% 수준에서 증가하고 있음을 확인하였다. 본 연구의 결과는 도심지 수공구조물의 설계빈도 영향을 진단하고, 근미래 발생가능한 확률강우량 변화에 따른 시간당 목표 강우량설정의 방법론을 제시하였다는데 의의가 있으며, 서울시의 방재성능목표 설정과 침수취약지역 해소를 위한 기후변화에 따른 수공구조물 설계 시 활용이 가능할 것으로 기대된다.