• 한국농공학회논문집
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• 제57권5호
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• pp.129-137
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• 2015

The objective of this study was to test the non-point source pollution (NPS) control by the vegetated ridge and silt fence through field monitoring. The experiment plots were established with three sizes which are 5 m width by 22 m length with 8 %, 3 % slope and 15m width by 15 m length with 6 % slope. Flumes with the floating type stage gages were installed at the outlet of each plot to monitor the runoff. For a rainfall monitoring, tipping bucket rain gage was installed within the experiment site. Water quality samples were monitored during the heavy rainfall occurred. The amount of rainfall from 4 monitored events ranged from 27.6 mm to 130 mm. The runoff reduction rate could vary depending on slope, soil, crop growth condition, rainfall amount, rainfall intensity, antecedent moisture condition, and many other factors. The runoff from vegetated ridge and silt fence treatment plots was 24.05 % and -8.28 % lower than that from control plot, respectively. The monitoring results showed that the average pollution loads reduced by vegetated ridge compared to control were BOD 36.62~53.60 %, SS 40.41~73.71 %, COD 39.34~56.41 %, DOC 49.08~53.67 %, TN 26.74~67.23 %, and TP 52.72~91.80 %; by silt fence compared to control were SS 41.73 %, COD 1.93 %, and TN 2.38 %. The paired t-test result indicated that the vegetated ridge and silt fence were statistically significant effect in SS load reduction, with a 5 % significant level. Monitored results indicated that vegetated ridge and silt fence were both effective to reduce the pollutant from the field surface runoff.

• 환경영향평가
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• 제22권1호
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• pp.39-50
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• 2013

Occurrence of landslides has been increasing due to extreme weather events(e.g. heavy rainfall, torrential rains) by climate change. Pyeongchang, Korea had seriously been damaged by landslides caused by a typhoon, Ewiniar in 2006. Moreover, the frequency and intensity of landslides are increasing in summer due to torrential rain. Therefore, risk assessment and adaptation measure is urgently needed to build resilience. To support landslide adaptation measures, this study predicted landslides occurrence using MaxEnt model and suggested susceptibility map of landslides. Precipitation data of RCP 8.5 Climate change scenarios were used to analyze an impact of increase in rainfall in the future. In 2050 and 2090, the probability of landslides occurrence was predicted to increase. These were due to an increase in heavy rainfall and cumulative rainfall. As a result of analysis, factors that has major impact on landslide appeared to be climate factors, prediction accuracy of the model was very high(92%). In the future Pyeongchang will have serious rainfall compare to 2006 and more intense landslides area expected to increase. This study will help to establish adaptation measure against landslides due to heavy rainfall.

• 대한원격탐사학회지
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• 제36권4호
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• pp.627-635
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• 2020

With the increasing severity of climate change, intense torrential rains are occurring more frequently globally. Flooding due to torrential rain not only causes substantial damage directly, but also via secondary events such as landslides. Therefore, accurate and prompt flood detection is required. Because it is difficult to directly access flooded areas, previous studies have largely used satellite images. Traditionally, water indices such asthe normalized difference water index (NDWI) and modified normalized difference water index (MNDWI) which are based on different optical bands acquired by satellites, are used to detect floods. In addition, as flooding likelihood is greatly influenced by the weather, synthetic aperture radar (SAR) images have also been used, because these are less influenced by weather conditions. In this study, we compared flood areas calculated from SAR images and water indices derived from Landsat-8 images, where the images were acquired at similar times. The flooded area was calculated from Landsat-8 and Sentinel-1 images taken between the end of May and August 2019 at Lijiazhou Island, China, which is located in the Changjiang (Yangtze) River basin and experiences annual floods. As a result, the flooded area calculated using the MNDWI was approximately 21% larger on average than that calculated using the NDWI. In a comparison of flood areas calculated using water indices and SAR intensity images, the flood areas calculated using SAR images tended to be smaller, regardless of the order in which the images were acquired. Because the images were acquired by the two satellites on different dates, we could not directly compare the accuracy of the water-index and SAR data. Nevertheless, this study demonstrates that floods can be detected using both optical and SAR satellite data.

• 한국습지학회지
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• 제16권1호
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• pp.93-102
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• 2014

2000년대 후반 이래로 홍수터를 활용한 생태공원이나 체육시설 등과 같은 다양한 친수시설들이 조성되었다. 또한 최근 강우강도 및 홍수 빈도의 증가로 인해 관련 피해가 급증하고 있으며, 이는 홍수터에 설치된 공원과 같은 친수시설들의 침수피해와 직접적으로 연관되므로, 극한강우 시 홍수터에서의 수치해석이 필요하다고 판단된다. 본 연구에서는 홍수터에서의 수위상승과 하강에 따른 수리학적 영향을 분석하기 위해 마름/젖음 모의가 가능한 준부정류 흐름해석모형인 FaSTMECH와 부정류 흐름해석모형인 Nays2D 모형을 이용하여 각 모델간의 태풍 사상시 시간에 따른 침수심 및 유속분포를 비교 분석하였다. 태풍 사상시 홍수터에서의 유속분포는 주수로에서의 유속에 비해 매우 낮은 유속을 보이고 있었으며, 홍수터에서는 침식보다는 토사퇴적 문제가 더 높을 것이라 판단된다.

• 통합자연과학논문집
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• 제1권2호
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• pp.89-114
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• 2008

Interrelationship between heavy rainfalls and related with low-level jets(LLJ) is analyzed by using fifty cases of heavy rainfall events occurred over the Korean peninsula from 1992 to 2001. Those cases are classified with four synoptical features. There are 32% chances that the low pressure exist in heavy rainfall over than 150 mm per day case by case. Secondly Changma front and front zone account for 28% of all cases. The ratio of marine tropical boundary type and trough type record 22% and 18% respectively. The moist and warm south-westerly winds associated with low-level jets have been induced convective instability and baroclinic instability. Therefore, heavy rainfall due to the approach of a low pressure occurred at September and before Changma. During the period of Changma, this type has been happened heavy rainfall when low pressure and stationary front has vibrated south and north. Changma type has longer the duration time of precipitation than other types. Third type, located with marine Tropical boundary, have mainly rained in August and September. The last trough case locally downpoured in short time with developing cell. The occurrence low-level jets related to heavy rainfall has increased over 12.5 m/s wind speed. The result is that 43 heavy rainfalls out of 50 cases reach peak at the time of maximum precipitation intensity. Also, the variation of wet number and K-index corresponded with the variation of wind speed. It is found that the number of frequency of low-level jets with southwestward direction has been increased and these jets are mainly passed from the southwest toward to the northeast of the Korean peninsula in that time.

• 한국전자통신학회논문지
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• 제15권2호
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• pp.371-378
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• 2020

강우는 토양 침식을 일으키는 가장 능동적인 힘 중 하나이다. 다양한 속도와 운동에너지를 가지고 낙하하는 우적은 토양에 충격을 주는 침식력으로 작용한다. 우적의 변동 속도와 운동에너지는 우적의 직경에 직접적으로 의존한다. 이 연구의 목적은 브라질 Alagoas주 Maceió 지역에서 강우에 의한 토양 침식을 산정 할 수 있는 알고리즘을 결정하는 것이다. 이를 위해 1분 간격의 강우 분포를 지속적으로 자동 측정하는 RD-69 디즈드로미터를 사용하여 2003년부터 2006년까지 침식성 강우 자료를 수집하였다. 독립 변수가 강수량인 지수 관계식과 독립 변수가 지속 시간과 최대 강도인 지수 관계식 형태로 최적화된 알고리즘이 결정되었다.

• Journal of the Korean Data and Information Science Society
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• 제27권5호
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• pp.1119-1131
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• 2016

Neyman-Scott 구형펄스모형 (Neyman-Scott rectangular pulses model; NSRPM)은 강우의 발생, 강우세포의 강우강도 그리고 지속시간으로 표현되는 점과정에 기초한 강우생성 모형으로, 기존의 구형펄스모형 (rectangular pulse model)과 비교해서 강우사상의 군집특성을 잘 반영하기 때문에 여러 연구에서 많이 사용되는 모형이다. 하지만 NSRPM의 매개변수를 추정하는데 있어서 모멘트를 이용한 여러가지 최적화 기법들은 그 계산이 복잡하고 또한 목적함수의 구성에 따라 추정값의 변동도 크게 나타난다. 이를 보완하기 위해서, 최근 누적강수량에 대한 근사적인 우도함수 (approximated likelihood function)와 이를 통해 NSRPM의 매개변수를 추정하는 방법이 소개되었다. 본 논문에선 이 근사적 우도함수를 바탕으로 계층적 베이지안 모형을 이용하여 NSRPM에 공간구조를 표현하고 이를 통해 강우생성 모형의 공간적 특성을 알아보고자 한다.

• 한국수자원학회논문집
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• 제38권1호
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• pp.59-71
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• 2005

빈번하게 발생하고 있는 산불은 산지유역에 과도한 토사유출 문제를 일으키고 있다. 산불 이후 산지사면에서 강우에 의한 토사유출은 지표식생인자에 의해 지배되며 지표식생은 시간의 경과에 따라 점차 회복되고 이는 토사유출을 저감시킨다. 본 연구에서는 민감도를 강우에너지에 대한 유출 및 토양침식량의 비로 정의하고, 지표인자 변화에 따른 유출 및 토양침식 민감도의 특성을 분석하였다. 그 민감도에 대한 매개변수들의 상관관계를 분석한 결과 지표식생지수와의 상관성이 가장 높았으며 지수함수적인 관계를 나타내었다. 산불이후 경과시간에 따른 민감도는 산불피해복구 대책공법과 산불의 강도 모두 적합한 감소 기울기를 보였다. 산불발생 년도에 따른 토양침식민감도의 변화에서는 산불발생 이후 약 5년이 경과하면 토양침식민감도 변화가 적어 안정적인 범위 이내로 접어드는 것이 확인되었다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2012년도 학술발표회
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• pp.20-25
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• 2012

New Zealand suffers from regular floods, these being the most common source of insurance claims for damage from natural hazard events in the country. This paper describes the origin and distribution of the largest floods in New Zealand, and describes the systems used to monitor and predict floods. In New Zealand, broad-scale heavy rainfall (and flooding), is the result of warm moist air flowing out from the tropics into the mid-latitudes. There is no monsoon in New Zealand. The terrain has a substantial influence on the distribution of rainfall, with the largest annual totals occurring near the South Island's Southern Alps, the highest mountains in the country. The orographic effect here is extreme, with 3km of elevation gained over a 20km distance from the coast. Across New Zealand, short duration high intensity rainfall from thunderstorms also causes flooding in urban areas and small catchments. Forecasts of severe weather are provided by the New Zealand MetService, a Government owned company. MetService uses global weather models and a number of limited-area weather models to provide warnings and data streams of predicted rainfall to local Councils. Flood monitoring, prediction and warning are carried out by 16 local Councils. All Councils collect their own rainfall and river flow data, and a variety of prediction methods are utilized. These range from experienced staff making intuitive decisions based on previous effects of heavy rain, to hydrological models linked to outputs from MetService weather prediction models. No operational hydrological models are linked to weather radar in New Zealand. Councils provide warnings to Civil Defence Emergency Management, and also directly to farmers and other occupiers of flood prone areas. Warnings are distributed by email, text message and automated voice systems. A nation-wide hydrological model is also operated by NIWA, a Government-owned research institute. It is linked to a single high resolution weather model which runs on a super computer. The NIWA model does not provide public forecasts. The rivers with the greatest flood flows are shown, and these are ranked in terms of peak specific discharge. It can be seen that of the largest floods occur on the West Coast of the South Island, and the greatest flows per unit area are also found in this location.

• 한국수자원학회논문집
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• 제51권10호
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• pp.887-893
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• 2018

본 연구에서는 신뢰성해석기법을 이용하여 우수관에 대한 최적설계기법을 제시하였다. 최근 빈번히 일어나고 있는 국지성호우에 대해 기존의 결정론적 설계기법으로는 우수관의 용량을 초과하여 도시침수가 일어나기 쉽다. 이러한 문제를 해결하기 위해서는 우수관의 설계변수들을 확률변수로 인식하는 추계학적 기법이 필요하다. 이를 위해서 본 연구에서는 FORM (First Order Reliability Method)을 사용하여 우수관의 신뢰성해석모형을 개발하였다. 개발된 신뢰성해석기법은 5개 지역의 실제 구축된 우수관에 적용하여 안전도를 분석하고 공사비증가에 따른 안전도의 변화를 분석하였다. 다섯 개 지역의 빈도별 강우강도를 분석하고 신뢰성해석을 통해 우수관의 용량초과확률을 정량적으로 산정할 수 있었다.