• Journal of Korea Water Resources Association
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• v.48 no.3
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• pp.169-183
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• 2015

As a basic work for river restoration, analysis on fluvial geomorphological characteristics is made using past and present data to understand close-to-nature geomorphic status. The Miho and the Naesung Rivers are targets of this study. Fluvial geomorphic variables including valley-floor width, sinuosity, bankfull width, channel gradient, bed material size, bankfull discharge and unit stream power are evaluated with dominant processes. Though common sand-bed rivers with similar catchment area, the Miho and the Naesung Rivers are different in terms of valley-floor width, channel shape variables and dominant processes related with longitudinal location. In addition, analyses on interrelationship among the geomorphological variables are carried. Bankfull width is shown to be proportional to bankfull discharge, as is in a rough agreement with the previous studies. Relationship of bankfull discharge and channel gradient shows meandering and braiding are prevalent in the Miho River, whereas the most of the sub-reaches of the Naesung River fall to braiding. Relationship of channel gradient with width-depth ratio indicates dune-ripple processes are dominant in the Miho River, while the Naesung River shows longitudinal diversity from braiding in the downstream sub-reaches to riffle-pool and plane-bed along the upper ones. Analyses based on the past data on a river in a close-to-nature status are thought to be rather reasonable in comparison with those on the same river in a engineered condition.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.1
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• pp.107-113
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• 2009

This study has been conducted for the long-term riverbed change prediction on Geum River and Miho Stream surrounding the planned Multifunctional Administrative City and the neighboring regions by the construction of a small dam. Based on the analysis of vertical riverbed changes of the cross-sectional data for the years 1988, 2002 and 2007, minimum bed elevation significantly decreased in both Geum River and Miho Stream in 2007 as compared to 1988. Compared to 2002, however, a slight elevation change was observed. To make a long-term prediction on riverbed changes by the construction of a small dam, a one dimensional HEC-RAS 4.0 model has been used. By the fixed bed model test, the water levels were calibrated. By using the cross-sectional data of 1988 and 2002, verification was conducted under a movable bed model. According to the prediction of riverbed changes for each scenario with varying height of small dam, minor impact is expected around Miho Stream while major impact is expected around Geum River by 2017, as the small dam height increases. If the small dam is 7m-high, for example, it's been simulated that 1.59m deposition would be expected around the upper stream of Miho Stream Confluence while 1.98m scour would be expected around the downstream of the small dam.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1125-1130
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• 2009

우리나라 연간 총수자원 1240억$m^3$ 가운데 42%에 해당하는 517억$m^3$는 증발산을 통해서 하늘로 올라가고 나머지 58%인 723억$m^3$는 하천으로 흘러간다(국토해양부, 2008). 이와 같이 증발산량은 지구 표면에서 대기로의 수증기 이동 현상으로 강수와 더불어 대기의 물 순환 및 수분 이동의 파악에 매우 중요한 지표로 사용되고 있다. 현재 기상청에서는 세계기상기구의 관측 기준에 따라 증발산량을 측정하고, 점추정 자료를 내삽법을 이용하여 유역면적 전체에 적용시키고 있다. 그러나 자연상태에서 증발산에 영향을 주는 요인이 매우 다양하기 때문에 점추정 자료를 통해 유역면적 전체에 대한 증발산량을 추정하는 방법은 많은 오차를 가져올 수 있다(유진웅, 2003). 이를 극복하기 위한 방법으로 RS 기법에 의한 증발산량 추정 방법과 함께 위성으로부터 획득할 수 있는 지표 및 대기 정보를 이용하여 광범위한 지역 내에서 공간적으로 불균일한 수분 분포를 추정하기 위하여 많은 알고리즘이 제안되었다. 본 연구에서는 위성영상을 이용하여 증발산량을 추정하는 모형가운데 SEBAL(Surface Energy Balance Algorithm for Land) Model을 상용소프트웨어에서 구현하고 충청북도에 위치한 미호천 유역에 대해 모형을 적용하여 증발산량을 추정하였다. 위성자료로는 2006년 9월 22일의 Landsat 5 TM 영상을 사용하였으며, DEM은 USGS DEM, 기상자료로는 청주시 기상연보를 활용하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.991-995
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• 2009

최근 기후변화 등으로 우리나라의 경우 강수일수는 감소한 반면 집중호우의 발생빈도는 증가하고 있다. 실제 가뭄과홍수와 같은 극치사상의 피해가 증가될 가능성과 이러한 재해로부터 인명 및 재산을 보호하고 효율적인 수자원 활용을 위해서는 장기간 강우-유출과정의 정확한 해석이 필수적이다. 본 연구는 미호천 유역을 대상으로 장기유출을 모의하기 위해 개념적 강우유출모형을 적용하였다. 본 연구의 개념적 강우유출모형은 PDM(Probability Distributed Model)으로 유역을 한 개의 단위구역으로 사용한 집중형(lumped) 모형이고, 분포형 모형에 비하여 간단 (parsimonious)하며 영국의 수자원 및 홍수 관리 목적으로 널리 사용되고 있다. 모형의 검정은 MC(Monte Carlo) 방법과 SCE-UA(Shuffled Complex Evolution-University of Arizona) 방법을 적용하였으며, NSE(Nash Sutcliffe Efficiency) 목적함수를 사용하여 모형의 성능을 검토하였다. 그 결과, MC 방법과 SCE-UA 방법 모두 NSE의 값 0.9 이상으로 만족할 만한 모의성능을 나타내었다. 분포형 모형에 비하여 적은 수문자료 및 검정변수를 갖는 PDM 모형을 수문자료의 취득이 용이하지 않은 중 소규모 유역에 적용하여 모형의 검정 및 유량산정에 있어 우수함을 확인하였다. 이에 우리나라 전역에 걸쳐 다양한 유역을 대상으로 PDM 모형의 검토가 요구되고, 향후 우리나라의 홍수량 산정 및 수자원 관리에 적용될 수 있다고 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.285-285
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• 2011

우리나라의 하천 상류지역의 유역들은 신뢰할 수 있는 수문자료의 미비로 인하여, 관행적으로 모형의 변수를 산정하여 강우유출모형을 적용하고 있다. 그러나 상류지역의 빈번한 홍수 피해 및 수자원관리의 문제발생 등으로 인하여 이러한 상류지역의 중소유역의 신뢰할 수 있는 홍수량산정 방법이 요구되고 있다. 이는 영국의 국가 홍수량 산정 표준방법(Flood Estimation Handbook)과같이 강우유출모형의 지역화를 통하여 해결 할 수 있다. 지역화를 위한 강우유출모형의 선정을 위하여 9개의 개념적 강우유출모형을 충청북도 미호천 상류 7개의 소유역에 적용하여 모형의 성능을 평가하였다. 이는 유효우량 산정을 위한 3개의 개념적 토양저류함수 모형(Soil Moisture Accounting: Modified Penman Type Model(MP), Catchment Wetness Index Model(CWI), Probability Distribution Model(PDM))과 3개의 유역유출을 위한 3개의 개념적 유출모형(Routing: 2-Conceptual Reservoir Model(2PAR), 3-Conceptual Reservoir Model(3PAR), Marcropore Model(2PMP))의 조합으로 총 9개의 모형을 검토하였다. 이를 검정기간(2004.01.01-2007.12.31) 과 검증기간(2008.01.01-2009.12.31)의 장단기 유출성능을 Nash Sutcliffe Efficiency 로 평가한 결과, 시간 단위의 단기모의에서는 CWI-2PMP와 PDM-2PMP모형이, 일 단위의 장기모의에서는 CWI-3PAR와 PDM-2PMP가 우수한 성능을 보이고 있다. 향후 금강 상류유역의 기본 강우유출모형으로 PDM-2PMP모형을 선정한다.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.1 s.24
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• pp.57-66
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• 2007

The purpose of this study is both the variation of hydrologic topographical informations extracted by using WMS and the quantitative effect of rainfalll-runoff simulation due to dividing watershed. Miho stream basin in Geum river was selected by this study. Watershed dividing method are determined by area, channel slope and channel length. Hydrological response of divided watershed using Clark method, SCS method and Snyder method was compared with actual measured flood hydrograph. As a results, area-based watershed dividing method are particularly suitable the hydrologic applications using SCS method. This study can be used as basic data for the phase of the runoff variation in Miho stream basin.

• Journal of Korea Water Resources Association
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• v.38 no.1
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• pp.49-57
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• 2005

The investigation and evaluation of river naturalness was conducted for sample rivers-Hongchungang, Mihochun, Naesungchun - using the method from previous paper 'The Evaluation of River Naturalness for Habitat Restoration : I. Proposal of Evaluation Method'. As a result, Hongchungang and Naesungchun, Mihochun showed 2$^{nd}$ Grades with averaged point 1.92, 1.43, and 2.31. Also comparison and examination of the relationship between water quality and river naturalness shows a little relation with coefficient of correlation 0.575. This result means that the evaluation of river naturalness can be possibly used as index to evaluate river ecology, from a different standpoint with water quality.oint with water quality.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.323-323
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• 2020

그래픽 처리 장치(Graphic Processing Unit: GPU)는 그래픽 처리 작업에 특화된 다수의 산술논리 장치(Arithmetic Logic Unit: ALU)로 구성되어 있어서 중앙 처리 장치(Central Processing Unit: CPU)보다 한 번에 더 많은 연산 수행이 가능하다. 본 연구는 GPU 가속 운동파모형을 실제 유역에 적용하여, GPU 가속 운동파 강우유출모형 결과에 대한 정확성과 연산 소요 시간에 대한 효율성을 확인하였다. GPU 가속 운동파모형은 분포형 강우유출모형의 수치모의 연산시간을 단축시키기 위해 CUDA 포트란을 이용하여 개발되었다. 분포형모형의 지배방정식은 운동파모형과 Green-Ampt모형으로 구성되었고, 운동파모형은 유한체적법을 이용하여 이산화 하였다. GPU 가속 운동파모형을 이용하여 금강의 미호천 유역에서 발생하는 강우유출현상을 모의 하였고, 동일한 유한체적법을 이용한 CPU(Central Processing Unit) 기반의 강우유출모형과 비교하였다. 그 결과 GPU 가속모형의 결과는 미호천 유역 하류단에서 관측한 결과와 유사한 결과를 나타냈다. 또한, 연산소요시간은 CPU 기반의 강우유출모형의 연산소요시간보다 단축되었으며, 본 연구에 사용된 장비를 기준으로 최대 100배 정도 단축되었다.

• Journal of Environmental Impact Assessment
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• v.27 no.6
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• pp.548-561
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• 2018

The objectives of this study were to construct a three-dimensional (3D) hydrodynamic and water quality model (EFDC) for the river reach between the Daecheong dam and the Sejong weir, which are directly affected by Gap and Miho streams located in the middle of the Geum River, and to evaluate the trophic status and water quality improvement effect according to the flow control and pollutant load reduction scenarios. The EFDC model was calibrated with the field data including waterlevel, temperature and water quality collected from September, 2012 to April, 2013. The model showed a good agreement with the field data and adequately replicated the spatial and temporal variations of water surface elevation, temperature and water quality. Especially, it was confirmed that spatial distributions of nutrients and algae biomass have wide variation of transverse direction. Also, from the analysis of algal growth limiting factor, it was found that phosphorous loadings from Gap and Miho streams to Sejong weir induce eutrophication and algal bloom. The scenario of pollutant load reduction from Gap and Miho streams showed a significant effect on the improvement of water quality; 4.7~18.2% for Chl-a, 5.4~21.9% for TP at Cheongwon-1 site, and 4.2~ 17.3% for Chl-a and 4.7~19.4% for TP at Yeongi site. In addition, the eutrophication index value, identifying the tropic status of the river, was improved. Meanwhile, flow control of Daecheong Dam and Sejong weir showed little effect on the improvement of water quality; 1.5~2.4% for Chl-a, 2.5~ 3.8% for TP at Cheongwon-1 site, and 1.2~2.1% for Chl-a and 0.9~1.5% for TP at Yeongi site. Therefore, improvement of the water quality in Gap and Miho streams is essential and a prerequirement to meet the target water quality level of the study area.

• Ecology and Resilient Infrastructure
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• v.9 no.1
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• pp.68-76
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• 2022

In this study, the Habitat Suitability Index (HSI) was calculated in the Miho stream of the Geum river system, and the environmental ecological flow by point was evaluated. Two points (St.3 and St.8) representing the up and downstream of Miho Stream were selected, in order to calculate the Habitat Suitability Index, the depth and velocity at point where each species is appeared were investigated. The Habitat Suitability Index (HSI) was calculated by the Washington Department of Fish and Wildlife (WDFW) method using the number collected by water depth and velocity section and the results of the flow rate survey. Two target species were selected in this study; dominant species and swimming species sensitive to flow. In the case of a single species of Zacco platypus, the water depth was 0.1 - 0.5 m and the velocity was 0.2 - 0.5 m/s. For species of swimming fish, the water depth was 0.2 - 0.5 m and the velocity was 0.2 - 0.5 m/s. The discharge-Weighted Useable Area (WUA) relationship curve and habitat suitability distribution were simulated at the Miho Stream points St.3 and St.8. At the upstream St.3 of Miho Stream, the optimal discharge was simulated as 4.0 m³/s for swimming fishes and 2.7 m³/s for Zacco platypus. At the downstream point of St.8, species of swimming fish were simulated as 8.8 m³/s and Zacco platypus was simulated as 7.6 m³/s. In both points, the optimal discharge of swimming fish was over estimated. This is a result that the Habitat Suitability Index for swimming fish requires a faster flow rate than the habitat conditions of the Zacco platypus. In the calculation of the minimum discharge, the discharge of Zacco platypus is smaller and is evaluated to provide more Weighted Useable Area. In the case of swimming fishes, narrow range of depth and velocity increases the required discharge and relatively decreases the Weighted Useable Area. Therefore, when calculating the Habitat Suitability Index for swimming fishes, it is more advantageous to calculate the index including the habitat of all fish species than to narrow the range.