• Journal of The Geomorphological Association of Korea
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• v.15 no.2
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• pp.55-65
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• 2008

In order to examine the runoff characteristics of scoria cones in Jeju Island, hydrological observations were conducted in the experimental basin (5.1 ha) of Eoseungsaeng-oreum which has been predominantly covered with Carpinus laxiflora and Quercus serrata. Although runoff has continuously occurred during the observed period, the baseflow gradually increased from April and decreased from October. The peak flow approximately corresponded to every rainfall events except for the rainfall events which has slight total precipitation and no previous precipitation. The experimental basin shows flash runoff response and short lag time; the mean lag time is 35.8 minutes. Although the runoff ratio of quick flow is proportional to total precipitation, the increasing rate is low and the maximum runoff ratio is 24.7%. In addition, the runoff ratio is less than 1% in 68.3% of the rainfall events, suggesting that the portion of quick flow to total precipitation is low. The rainfall events with relatively long event time demonstrated a secondary peak generated by translatory flow. The runoff characteristics seem to be related to local impermeable beds in the experimental basin.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.5-5
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• 2023

제3차 우주개발 진흥 기본계획의 일환으로써 개발되는 차세대 중형위성 5호인 수자원위성은 수자원/수재해 감시 전용 위성으로 2025년 발사 예정이다. 수자원위성의 메인 센서인 C-band 영상레이더(Synthetic Aperture Radar, SAR)는 기상조건 및 주야 상관없이 지표면 관측이 가능한 센서로 급변하는 수재해 양상에 효과적으로 대응하기 위해 탑재된 센서이다. 본 연구사업은 차세대 수자원위성의 효과적 활용 방안 및 SAR 자료기반의 활용산출물 및 주제도 서비스를 위한 알고리즘 구조설계 및 표출시스템 시범개발을 목표로 하고 있으며, 홍수/가뭄/안전/환경모니터링을 주제로 수자원 및 원격탐사 분야의 다학제적 전문가들로 구성된 컨소시엄을 구성하여 추진하고 있다. 본 연구의 내용은 가뭄 모니터링을 위해 개발 중인 SAR 기반 토양수분과 농업적 가뭄지수 산정 알고리즘 개발 및 공간적 표출을 포함한다. 토양수분은 SAR 영상에서 지표피복별로 추출된 후방산란계수와 수문학적 개념의 융합을 통해 논/밭/산림에 대해 산정한다. 물리적 특성에 기반한 변화탐지모델을 활용해 토양수분량을 추출 후, 기계학습기법과 S C S - C N 방법에서 파생된 수문학적 개념 5일 선행강우량과 결합한 토양수분 산정 알고리즘을 개발하였다. 산정된 토양수분을 기반으로, 논 지역은 벼 재배에 따른 담수 시기를 고려한 토양의 포화/불포화상태, 밭 지역은 토양 종류에 따른 토양의 물리적 특성, 산림 지역은 수문학적 개념 및 식생지수를 활용하여 가뭄 판단 기준을 구축하고, 가뭄의 해갈 여부와 해갈되는 시점의 강우량을 산정 가능한 알고리즘을 개발하였다. 개발된 가뭄 모니터링 기법은 향후 고도화, 최적화 및 안정화를 통해 수자원위성의 핵심 활용기술로써 구현할 계획이다.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.05a
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• pp.249-254
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• 2003

분석에 이용된 격자망은 동곡, 고로, 미성, 병천, 효령 및 무성지점에 각각 12개, 30개, 45개, 76개, 46개 및 1265개의 조격자를 구성하였으며 하천의 수로방향 및 경사형태를 세분화하기 위하여 각 지점에 대하여 8개, 24개, 24개, 44개, 12개 및 64개의 세격자로 분할하였다. AGNPS를 이용한 첨두유량의 모의발생 결과치가 동곡, 고로, 미성, 병천, 효령 및 무성지점에서 측정값과 비교하여 각 호우사상별로 상대오차가 1.0~25.0%, 4.0~27.0%, 7.0~29.2%, 2.0~23.9%, 3.0~25.0% 및 3.6~21.0%의 차이를 나타내었다. 분석결과에서 AMCII조건에서는 관측치와 분석결과치가 유사하게 나타났으나 AMCI조건에 대해서는 상대적으로 작은 값을 보였으며 AMCIII조건에서는 다소 큰 값으로 분석되었다. SCS방법에서 제안하는 AMC조건별 CN값을 우리 실정에 적합하도록 수정 보완하기 위한 수정 유출곡선지수 $CN_{m}$ /I과 $CN_{m}$/III을 재구성하였으며, 여기에 적용되는 수정 유출 곡선지수식의 계수 a를 추정한 결과, 기왕에 발표된 연구결과와 거의 일치된 경향을 나타내었다. 제안된 수정 CN식을 이용하여 산정한 결과치와 관측치는 거의 유사하게 나타났다. AGNPS모델에 의한 유출량 산정에 있어 수문학적 토양피복형수(CN)의 결정을 위하여 선행강우량과 토양의 공극율 및 지형인자인 각 셀마다의 유역경사를 이용하여 관계식(CN =f($X_1$, $X_2$, $X_3$))을 유도하였으며, 분석 결과에서 CN이 선행강우량과 가장 밀접한 관계가 있음을 알 수 있었으며 유역경사, 토양의 공극율 순으로 나타났다..88mg/$\ell$~의 범위로 나타났다. 무태교 지점에서의 총인의 농도는 0.52mg/$\ell$~0.99mg/$\ell$~의 범위이었다. 신천에 금호강물을 혼합한 이후에도 부유물질, 생화학적산소요구량, 암모니아태 질소, 총인 등의 농도가 개선되지 않았다. 즉 금호강물의 혼합은 신천수질환경사업소에서 배출되는 방류수에 함유되어 있을 2차 오염물질의 희석이라는 이점외의 수질개선효과는 확인되지 않았다.l years and a new type of transfer crane has been developed. Design concepts and control methods of a new crane will be introduced in this paper.and momentum balance was applied to the fluid field of bundle. while the movement of′ individual material was taken into account. The constitutive model relating the surface force and the deformation of bundle was introduced by considering a representative prodedure that stands for the bundle movement. Then a fundamental equations system could be simplified considering a steady state of the process. On the basis of the simplified model, the simulation was performed and the results co

• Journal of Korean Society of Disaster and Security
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• v.12 no.2
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• pp.15-24
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• 2019

In the previous study, the rainfall data of 1 hour, 6 hours and 3 days were used as the rainfall criterion according to the grade to trigger the debris flow in the highway area, using the rainfall data of Gangwon area and the rainfall time-series data at the spot where the debris flow occurred. In this study, we propose an early warning criterion of the highway debris flow triggering through appropriate combination of three rainfall criteria selected through previous studies and adjustments of rainfall criterion in the highway debris flow triggering. In addition, simulations were conducted using the time-series rainfall data of 2010~2012, which had a large amount of precipitation for the five sites where debris flows occurred in 2013. As a result of the study, the criteria for the early warning of highway unsteadiness on the highway were prepared. In case of the grade-based adjustment, it is preferable to apply the unified rating to the grade B. Also, if the fatigue of the monitoring is not a problem, adjusting it to A or S may be a way to positively cope with the occurrence of highway debris flow.

• Journal of Korea Water Resources Association
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• v.56 no.2
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• pp.115-124
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• 2023

Currently, as the frequency of extreme weather events increases, the scale of damage increases when extreme weather events occur. This has been providing forecast information by investing a lot of time and resources to predict rainfall from the past. However, this information is difficult for non-experts to understand, and it does not include information on how much damage occurs when extreme weather events occur. Therefore, in this study, a risk matrix based on heavy rain damage rating was presented by using the impact forecasting standard through the creation of a risk matrix presented for the first time in the UK. First, through correlation analysis between rainfall data and damage data, variables necessary for risk matrix creation are selected, and PERCENTILE (25%, 75%, 90%, 95%) and JNBC (Jenks Natural Breaks Classification) techniques suggested in previous studies are used. Therefore, a rating standard according to rainfall and damage was calculated, and two rating standards were synthesized to present one standard. As a result of the analysis, in the case of the number of households affected by the disaster, PERCENTILE showed the highest distribution than JNBC in the Yeongsan River and Seomjin River basins where the most damage occurred, and similar results were shown in the Chungcheong-do area. Looking at the results of rainfall grading, JNBC's grade was higher than PERCENTILE's, and the highest grade was shown especially in Jeolla-do and Chungcheong-do. In addition, when comparing with the current status of heavy rain warnings in the affected area, it can be confirmed that JNBC is similar. In the risk matrix results, it was confirmed that JNBC replicated better than PERCENTILE in Sejong, Daejeon, Chungnam, Chungbuk, Gwangju, Jeonnam, and Jeonbuk regions, which suffered the most damage.

• Journal of Wetlands Research
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• v.6 no.3
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• pp.119-126
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• 2004

In recent, the critical rainfall duration concept is widely used but we do not have understandable criteria yet. However, the critical rainfall duration is usually calculated considering concentration time, runoff model using effective rainfall, and unit hydrograph for the estimation of design flood. This study is to derive the regression equations between the critical rainfall duration and hydrologic components such as the basin area, slope, length, CN, and so on. We use a GIS tool which is called the ArcView for the estimation of hydrologic components and the HEC-1 module which is provided in WMS model is used for the runoff computation. As the results, the basin area, basin slope, and basin length had a great influence on the estimations of peak runoff and critical rainfall duration. We also investigated the sensitivities for the peak runoff and critical duration of rainfall from the correlation analysis for the involved components in the runoff estimation.

• Journal of Korean Society of Forest Science
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• v.101 no.1
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• pp.28-35
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• 2012

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 = $94.569{\cdot}exp$($-0.068{\cdot}ARI$)($R^2$=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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6B
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• pp.597-603
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• 2006

The purpose of this study is to improve the short term rainfall forecast skill using neural network model that can deal with the non-linear behavior between satellite data and ground observation, and minimize the flood damage. To overcome the geographical limitation of Korean peninsula and get the long forecast lead time of 3 to 6 hour, the developed rainfall forecast model took satellite imageries and wide range AWS data. The architecture of neural network model is a multi-layer neural network which consists of one input layer, one hidden layer, and one output layer. Neural network is trained using a momentum back propagation algorithm. Flood was estimated using rainfall forecasts. We developed a dynamic flood inundation model which is associated with 1-dimensional flood routing model. Therefore the model can forecast flood aspect in a protected lowland by levee failure of river. In the case of multiple levee breaks at main stream and tributaries, the developed flood inundation model can estimate flood level in a river and inundation level and area in a protected lowland simultaneously.

• The Journal of Engineering Geology
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• v.3 no.2
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• pp.101-114
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• 1993

GIS technique was applied to identify the regional hydrologic units for groundwater exploitation and recharge analysis in a study area. The technique was very effective to identify the potential areas for groundwater exploitation, and for groundwater management & land use planning. GIS database of environmental resources was complied from a variety of sources and scales as the foundation for analysis, including digitizing and scanning of hardcopy maps. A DEM(Digital Elevation Model) was used to dassify slopes, and identify problematic drainage system. Quantitative analysis of environmental resources helps us to develop the scoring system of GIS model, which evaluates each resource in relation to the others and reflects the relative importance of each resource. ARC4NFO was used to construct digital database, and the cartographic simulation techniques were applied in order to create new maps.

• Journal of Wetlands Research
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• v.10 no.2
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• pp.105-114
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• 2008

Growth in population and urbanization has progressively increased the loadings of pollutants from non-point sources as well as point sources. Separated sewer overflows(SSO) have been considered as a major cause of water-quality deterioration of natural water-courses in the vicinity of the heavily urbanized areas. The factors defining the magnitude and occurrence of SSO are site-specific. It is important to know exact properties of pollutants contained in SSO to address water quality impacts that are caused by SSO inputs to the receiving waters. Site and event parameters found to have significant influences on urban runoff pollutant EMCs include total event rainfall, antecedent dry period, rainfall intensity. In this study, a field survey was carried out in some selected areas of Cheongju city. Literature from previous similar studies was consulted and some important factors affecting the runoff characteristics of urban drainage areas were analyzed for some selected survey points. It was found that the factors most affecting BOD are the number of dry days prior to rainfall and the intensity of the rainfall. The factor most affecting CODcr is the number of dry days prior to rainfall. The factors most affecting SS are the amount of rainfall and the number of dry days prior to rainfall. The factor most affecting TN is the amount of rainfall. The factor most affecting TP is the amount of rainfall and the number of dry days prior to rainfall.