• 한국수자원학회논문집
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• 제38권10호
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• pp.801-810
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• 2005

자연 하천으로부터 홍수유출을 추정할 경우, 반드시 고려해야 할 중요한 인자들 중의 하나는 지체시간이다. 지체 시간은 집수형상디스크립터로 표현될 수 있는 유역의 형태적 특성의 영향아래 있음이 잘 알려져 있다. 본 논문에서는 Moussa(2003)에 의하여 제안된 등가타원의 기하학적 특성에 대한 개념을 유역 출구에 대한 지형학적 순간단위도 (GIUH)의 지체시간 산정에 적용한다. 강우-유출 관측 자료에 대한 지체시간은 Nash(1957)가 제안한 적률법을 이용하여 산정하고, GIUH 유도에는 지형학에 기초한 절차가 적용된다. 국내 3개 유역에 대한 적용사례를 통하여, 유역의 형태적 특성과 수문학적 응답사이의 관계를 고찰한다. 또한 상류지역으로부터 하류지역까지 등가타원 형상의 변화양상이 시험된다. 그 결과, 수문학적 응답특성과 디스크립터 사이에는 비교적 우수한 관계가 존재함이 확인되었고 타원의 형상은 하류방향을 따라 원의 형태로 접근해 감을 확인할 수 있었다. 본 연구 결과는 미계측 유역으로 확대 적용이 가능할 것으로 판단된다.

• Journal of Forest and Environmental Science
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• 제34권4호
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• pp.293-303
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• 2018

Sumber Jaya (54,194 hectares) is a district in West Lampung, Indonesia, located at the upper part of Tulang Bawang watershed. This watershed is one major water resource for Lampung Province, but has become a focal point of discussion because of the widespread conversion of forestland to coffee plantations and human settlements which lead to environmental and hydrological problems. This research aimed to evaluate Sumber Jaya watershed affecting by rapid land use change using hydrological methods as a base for watershed management. Nested catchment structure consisted of eight sub-catchments was employed in this research to assess scaling issues of land use change impacts on rainfall-runoff connections. Six tipping bucket rain gages were installed on the hill slopes of each sub-catchment and Parshall flumes were installed at the outlets of each sub-catchment to monitor stream flow. First, unit hydrograph that expressed the relationship of rainfall and runoff was computed using IHACRES model. Second, unit hydrograph was also constructed from observations of input and response during several significant storms with approximately equal duration. The result showed that most of the storm flow from these catchments consisted of slow flow. A maximum of about 50% of the effective rainfall became quick flow, and only less than 10% of remaining effective rainfall which was routed as slow flow contributed to hydrograph peaks; the rest was stored. Also, comparing peak responses and recession rates on the hydrograph, storm flow discharge was generally increased slowly on the rising limb and decreased rapidly on the falling limb. These responses indicated the soils in these catchments were still able to hold and store rain water.

• 대한토목학회논문집
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• 제40권2호
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• pp.209-215
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• 2020

자연적인 가뭄의 발생특성을 이해하는 데 있어서는 서로 다른 유형의 가뭄 사이의 시공간적 관계를 해석하는 것이 매우 중요하다. 본 연구에서는 가뭄 지속시간과 3차원(즉, 위도, 경도 및 시간)의 공간 범위가 겹치는 것을 고려하여 기상 및 수문학적 가뭄사상을 정의하고 전이특성을 해석하였다. 이는 시공간적 가뭄 특성인자(지속기간, 면적, 심도, 중심)를 기반으로 하여 가뭄의 공간적 재현특성과 더불어 시간이라는 연속적인 개념을 결합한다는 것을 의미한다. 이처럼 개발된 시공간적 가뭄전이 특성을 고려한 가뭄지도는 향후 국지적으로 빈번히 발생하는 수문학적 가뭄의 발생 원인을 발견하고, 가뭄에 대한 효율적인 대응방안을 마련하는 데 활용도가 매우 높을 것으로 기대된다.

• 한국물환경학회지
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• 제32권6호
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• pp.582-588
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• 2016

The hydrological simulation program FORTRAN (HSPF) is a comprehensive watershed model that employs the hydraulic function table (FTABLE) (depth-area-volume-flow relationship) to represent the geometric and hydraulic properties of water bodies. The hydraulic representation of the HSPF model mainly depends on the accuracy of the FTABLES. These hydraulic representations determine the response time of water quality state variables and also control the scour, deposition, and transport of sediments in the water body. In general, FTABLES are automatically generated based on reach information such as mean depth, mean width, length, and slope along with a set of standard assumptions about the geometry and hydraulics of the channel, so these FTABLES are unable to accurately describe the geometry and hydraulic behavior of rivers and reservoirs. In order to compensate the weakness of HSPF for hydraulic modeling, we generated alternate method to improve the accuracy of FTABLES for rivers, using the surveyed cross sections and rating curves. The alternative method is based on the hydraulics simulated by HEC-RAS using the surveyed cross sections and rating curves, and it could significantly improve the accuracy of FTABLES. Although the alternate FTABLE greatly improved the hydraulic accuracy of the HSPF model, it had little effect on the hydrological simulation.

• Environmental Engineering Research
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• 제25권3호
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• pp.267-273
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• 2020

This Hydrokinetic energy system is the process of extracting energy from rivers, canals and others sources to generate small scale electrical energy for decentralized usage. This study investigates the application of Soil and Water Assessment Tool (SWAT) in Geographical Information System (GIS) environment to evaluate the theoretical hydrokinetic energy potentials of selected Rivers (Asa, Awun and Oyun) all in Asa watershed, Kwara state, Nigeria. SWAT was interfaced with an open source GIS system to predict the flow and other hydrological parameters of the sub-basins. The model was calibrated and validated using observed stream flow data. Calibrated flow results were used in conjunction with other parameters to compute the theoretical hydrokinetic energy potentials of the Rivers. Results showed a good correlation between the observed flow and the simulated flow, indicated by ash Sutcliffe Efficiency (NSE) and R² of 0.76 and 0.85, respectively for calibration period, and NSE and R² of 0.70 and 0.74, respectively for the validation period. Also, it was observed that highest potential of 154.82 MW was obtained along River Awun while the lowest potential of 41.63 MW was obtained along River Asa. The energy potentials obtained could be harnessed and deployed to the communities around the watershed for their energy needs.

• 한국수자원학회논문집
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• 제44권3호
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• pp.231-248
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• 2011

본 연구에서는 기후변화 요소를 반영하여 홍수취약성지표 (Flood Vulnerability Index, FVI)를 개발하였고 이를 북한강 유역의 6개 중권역에 적용하였다. 기후변화 요소를 고려하기 위해 IPCC의 CGCM3 모형의 A1B와 A2 시나리오를 이용하였고 일단위로 축소화하기 위해 SDSM (Statistical Downscaling Model) 모형을 이용하였다. 홍수취약성 인자를 선정하기 위해 지속가능성 평가모형인 추진력-압력-상태-영향-반응 (Driver-Pressure-State-Impact-Response, DPSIR) 모형을 이용하였고 기후변화로 인한 홍수유출의 특성분석은 연속유출모의모형인 HSPF (Hydrological Simulation Program-Fortran)를 이용하였다. 본 연구에서 개발된 홍수취약성지수는 유역의 현상태 및 기후변화의 영향으로 인한 잠재적 취약성을 정량적인 하나의 지수로 간결하게 표현할 수 있어서 장기 수자원 및 유역관리 정책수립에 사용될 수 있을 것으로 기대된다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.649-654
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• 2005

Shallow slope failures in residual soil during periods of prolonged infiltration are common over the world. One of the key factors that dominate slope stability is hydrological response associated with infiltration. Hence, the soil-water profile during rainfall infiltration into unsaturated soil must me examined to evaluate slope stability. However, the hydraulic response of unsaturated soil is complicated by inherent uncertainties of the soil hydraulic properties. This study presents a methodology for assessing the effects of parameter uncertainty of hydraulic properties on the response of a analytical infiltration model using first-order reliability method. The unsaturated soil properties are considered as uncertain variables with means, standard deviations, and marginal probability distributions. Sensitivities of the probabilistic outcome to the basic uncertainties in the input random variables are provided through importance factors.

• 한국수자원학회논문집
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• 제50권5호
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• pp.347-358
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• 2017

본 연구에서는 호우 방향성에 의한 유역 유출응답 특성을 살펴보았다. 이를 위해 호우와 하천망의 방향적 특성을 확률밀도함수로 정량화하였고, 각 방향성 함수를 회선적분하여 호우 방향성의 고려 유무에 따른 유출응답 특성을 비교하였다. 그 결과, 호우 방향성을 고려한 유출모의 결과는 호우 방향성을 고려하지 않은 경우에 비해 관측 유출자료와 더욱 유사함을 알 수 있었다. 이러한 결과는 호우 방향성을 고려한 유역 반응함수에 의해 유출모의 결과가 보다 개선될 수 있음을 나타낸다. 따라서 본 연구성과는 호우 방향성에 따른 유역 반응함수의 비선형성을 고려함으로써 유출모의의 불확실성을 줄이는데 기여할 수 있을 것으로 기대된다.

• 한국농공학회논문집
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• 제65권5호
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• pp.37-49
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• 2023

The drought risk has been increasing recently due to climate change causing the extreme climate to be more frequent. In order to supply agricultural water stably under drought, it is necessary to operate an agricultural reservoir in response to drought. To this end, it is crucial to establish appropriate drought response operation rules considering weather conditions and reservoir status. In the reservoir operation simulation, the supply amount differs from the actual reservoir supply for many reasons, including maintaining water levels for supply and accommodating farmers' requests. So, for a more realistic reservoir operation simulation, it is necessary to reflect the reservoir operation rules of the actual water management site. Therefore, in this study, through a survey, the standards for limitation of agricultural water supply applied to agricultural reservoirs in Korea were investigated, and the criteria for drought response reservoir operation (DRO) were established based on the survey. Then, the DRO was applied to the irrigation period for nine subject reservoirs. The applicability was evaluated by comparing the DRO result to the operation result of HOMWRS (Hydrological Operation Model for Water Resources System). The reservoir drought index, storage rate, and daily supply were compared for evaluation. From the result, DRO showed more stable operation results in most cases against drought as it has fewer days of water supply limitation and a somewhat reservoir storage rate which can be utilized for prolonged drought.

• 한국지하수토양환경학회지:지하수토양환경
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• 제28권5호
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• pp.12-24
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• 2023

The Songji lagoon is brackish environment with a mixture of saline and fresh water, and the interaction of groundwater-lagoon water creates a physicochemical gradient. Although some studies have been conducted on the hydrological and geochemical characteristics of the Songji lagoon, microbial ecological studies have not yet been conducted. In this study, we investigated the effect of groundwater and surface water interaction on water quality as well as microbial community changes in the Songji Lagoon using 16S rRNA gene sequencing. Hydrochemical analyses show that samples were classified as 5 hydrochemical facies (HF) and hydrochemical facies evolution (HFE) revealed the intrusion phase was more dominant (57.9%) than the freshening phase (42.1%). Higher microbial diversity was found in freshwater in comparison to saline water samples. The microbial community at the phylum level shows the most dominance of Proteobacteria with an average of 37.3%, followed by Bacteroidota, Actinobacteria, and Patescibacteria. Heat map analyses of the top 18 genera showed that samples were clustered into 5 groups based on type, and Pseudoalteromonas could be used potential indicator for seawater intrusion.