• 한국농공학회논문집
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• 제58권1호
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• pp.27-38
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• 2016

More severe and frequent flood and drought have increased the attentions on the river management. In particular, baseflow is an important element among many streamflow characteristics because streamflow is mainly consisted of direct runoff and baseflow. In this regard, this study attempted to analyze the relationship between streamflow variability and baseflow contributions on Nakdong river basin. For this, two Streamflow Variability Indices (SVI) were used: Coefficient of Variation (CV) and Coefficient of Flow Regime (CFR). Furthermore, baselow separation was individually conducted by three methods (PART, WHAT and BFLOW), and based on this, Baseflow Index (BFI) was calculated. Also, we used the daily streamflow data retrieved from 27 gauge stations in Nakdong river basin for baseflow separation. The results showed that BFI calculated by three models ranges from 0.14 to 0.90 for 27 gauge stations. For SVI, BFI has much higher correlation with CV than with CFR. Also, the inversely proportional relationship between BFI and CV showed that higher baseflow contribution, less streamflow variability.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2022년도 학술발표회
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• pp.140-140
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• 2022

Recently an accurate quantification of streamflow under various climatological and anthropogenic factors and separation of their relative contribution remains challenging, because variation in streamflow may result in hydrological disasters. In this study, we evaluated the factors responsible for variation in streamflow in Korean watersheds, quantified separately their contribution using different Budyko-based functions, and identified hydrological breakpoint points. After detecting that the hydrological break point in 1995 and time series were divided into natural period (1966-1995), and disturbed period (1996-2014). During the natural period variation in climate tended to increase change in streamflow. However, in the disturbed period both climate variation and anthropogenic activities tended to increase streamflow variation in the watershed. Subsequently, the findings acquired from different Budyko-based functions were observed sensitive to selection of function. The variation in streamflow was observed in the response of change in climatic parameters ranging 46 to 75% (average 60%). The effects of anthropogenic activities were observed less compared to climate variation accounts 25 to 54% (average 40%). Furthermore, the relative contribution was observed to be sensitive corresponding to Budyko-based functions utilized. Moreover, relative impacts of both factors have capability to enhance uncertainty in the management of water resources. Thus, this knowledge would be essential for the implementation of water management spatial and temporal scale to reduce the risk of hydrological disasters in the watershed.

• 한국측량학회지
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• 제33권3호
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• pp.163-172
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• 2015

This study examined the potential effects of urban growth on streamflow in the Gyungan River watershed, Korea, using urban containment scenarios. First, two scenarios (conservation and development) were established, and SLEUTH model was adapted to predict urban growth into the year 2060 with 20 years interval under two scenarios in the study area. Urban growth was larger under scenario 2, focusing on development, than under scenario 1, focusing on conservation. Most urban growth was predicted to involve the conversion of farmland, forest, and grasslands to urban areas. Streamflow in future periods under these scenarios was simulated by the Soil and Water Assessment Tool (SWAT) model. Each scenario showed distinct seasonal variations in streamflow. Although urban growth had a small effect on streamflow, urban growth may heighten the problems of increased seasonal variability in streamflow caused by other factor, such as climate change. This results obtained in this study provide further insight into the availability of future water resource and can aid in urban containment planning to mitigate the negative effects of urban growth in the study area.

• Water Engineering Research
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• 제5권2호
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• pp.81-99
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• 2004

Long term streamflow regime under virtual climate change scenario was examined. Rainfall forecast simulation of the Canadian Global Coupled Model (CGCM2) of the Canadian Climate Center for modeling and analysis for the IPCC SRES B2 scenario was used for analysis. The B2 scenario envisions slower population growth (10.4 billion by 2010) with a more rapidly evolving economy and more emphasis on environmental protection. The relatively large scale of GCM hinders the accurate computation of the important streamflow characteristics such as the peak flow rate and lag time, etc. The GCM rainfall with more than 100km scale was downscaled to 2km-scale using the space-time stochastic random cascade model. The HEC-HMS was used for distributed hydrologic model which can take the grid rainfall as input data. The result illustrates that the annual variation of the total runoff and the peak flow can be much greater than rainfall variation, which means actual impact of rainfall variation for the available water resources can be much greater than the extent of the rainfall variation.

• 한국수자원학회논문집
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• 제47권5호
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• pp.491-500
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• 2014

하천수 가뭄을 평가하기 위하여 임계수준 방법을 이용한 하천수 가뭄지수 (streamflow drought index)를 소개하고 섬진강댐의 유입량을 대상으로 적용하였다. 사용한 임계수준은 고정, 월별 및 일별로써 연도별 가뭄의 1~3순위 분석결과, 1984년, 1988년과 1995년이 수문학적 가뭄의 크기도 컸고 오랫동안 지속되었다. 총 물 부족량과 지속기간의 극한값을 연도별로 비교해 본 바, 1984년, 1988년, 1995년과 2001년에 발생하였던 사상이 심각한 수준이었다. 또한 고정 임계수준은 계절 변동성을 반영하지못하는 단점이 있어서 최소한계절 이하의 임계수준 사용이 요구되었지만 월별과 일별로 정해진 임계수준은 적정한 것으로 판단되었다. 본 연구에서 제안한 방법론은 갈수예보 및 저수지 용량결정에 활용될 수 있겠다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2018년도 학술발표회
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• pp.317-317
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• 2018

Baseflow which is one of the unmeasurable components of streamflow and slowly flows through underground is important for water resource management. Despite various separation methods from researches preceded, it is difficult to find a significant separation method for baseflow separation. This study applied the MRC method and developed the improved approach to separate baseflow from total streamflow hydrograph. Previous researchers utilized the whole streamflow data of study period at once to derive synthetic MRCs causing unreliable results. This study has been proceeded with total nine areas with gauging stations. Each three areas are selected from 3 domestic major watersheds. Tool for drawing MRC had been used to draw MRCs of each area. First, synthetic MRC for whole period and two other MRCs were drawn following two different criteria. Two criteria were set by different conditions, one is flow condition and the other is seasonality. The whole streamflow was classified according to seasonality and flow conditions, and MRCs had been drawn with a specialized program. The MRCs for flow conditions had low R2 and similar trend to recession segments. On the other hand, the seasonal MRCs were eligible for the baseflow separation that properly reflects the seasonal variability of baseflow. Comparing two methods of assuming MRC for baseflow separation, seasonal MRC was more effective for relieving overestimating tendency of synthetic MRC. Flow condition MRCs had large distribution of the flow and this means accurate MRC could not be found. Baseflow separation using seasonal MRC is showing more reliability than the other one however, if certain technique added up to the flow condition MRC method to stabilize distribution of the streamflow, the flow conditions method could secure reliability as much as seasonal MRC method.

• 한국수자원학회논문집
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• 제36권1호
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• pp.33-44
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• 2003

유황곡선은 하천유량의 변동성을 함축적으로 나타내고 있다. 본 연구는 인위적인 유량조절이 없는 자연하천의 무차원 유황곡선을 조사하여 보았다. 유황분석은 IHP대표유역과 대하천 주요 수위관측 지점의 수문자료를 토대로 수행하였다. 유황은 유역면적에 의존하나 유황계수는 판수계수를 제외하면 유역면적의 변화에 민감하지 않았으며 특히 풍수계수는 일정한 값을 나타내었다. 본 연구에서 평수량에 대한 갈수량 및 저수량의 비로 정의한 유황변동계수는 유역면적이 증가하면 작아지고 하천 경사의 증가에 따라 커진다. 저수유황변동에 비하여 갈수유황 변동이 유역면적의 변화에 영향을 받는 것으로 보여진다.

• 한국농공학회논문집
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• 제59권3호
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• pp.41-50
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• 2017

The purpose of this study were to evaluate the effect of best management practices (BMPs) of Haean highland agricultural catchment ($62.8km^2$) under future climate change using SWAT (Soil and Water Assessment Tool). Before future evaluation, the SWAT was setup using 3 years (2009~2011) of observed daily streamflow, suspended solid (SS), total nitrogen (T-N), and total phosphorus (T-P) data at three locations of the catchment. The SWAT was calibrated with average 0.74 Nash and Sutcliffe model efficiency for streamflow, and 0.78, 0.63, and 0.79 determination coefficient ($R^2$) for SS, T-N, and T-P respectively. Under the HadGEM-RA RCP (Representative Concentration Pathway) 4.5 and 8.5 scenarios, the future precipitation and maximum temperature showed maximum increases of 8.3 % and $4.2^{\circ}C$ respectively based on the baseline (1981~2005). The future 2040s and 2080s hydrological components of evapotranspiration, soil moisture, and streamflow showed changes of +3.2~+17.2 %, -0.1~-0.7 %, and -9.1~+8.1 % respectively. The future stream water quality of suspended solid (SS), total nitrogen (T-N), and total phosphorus (T-P) showed changes of -5.8~+29.0 %, -4.5~+2.3 %, and +3.7~+17.4 % respectively. The future SS showed wide range according to streamflow from minus to plus range. We can infer that this was from the increase of long-term rainfall variability in 2040s less rainfalls and 2080s much rainfalls. However, the results showed that the T-P was the future target to manage stream water quality even in 2040s period.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.146-146
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• 2015

하천관리는 직접유출과 기저유출로 구성된 하천유량의 특성을 이해하는 것으로부터 시작된다. 따라서 직접유출과 기저유출의 특성은 직접적으로 하천유량의 변동성으로 전달된다. 이러한 점을 고려했을 때 전략적인 하천관리를 위해서는 직접유출/기저유출과 하천유량의 관계를 분석하는 것이 필요하다. 이를 대해 본 연구의 목적은 하천유량의 변동성과 기저유출비(Baseflow Index, BFI)의 관계를 분석하고, 이러한 관계를 일관성 있게 나타낼 수 있는 하천유량 변동성 지표(Streamflow Variability Index, SVI)를 제시하는 것이다. 본 목적을 달성하기 위해 국내 총 91개 유량관측소를 대상으로 유황계수, R-B Index(Richards-Baker Flashiness Index), 변동계수(Coefficient of Variation), Q5:Q95 ratio 등의 SVI를 적용하였다. 이와 더불어, BFI를 산정하기 위하여 기저유출 분리 모형인 WHAT, PART, HYSEP, BFLOW를 사용하였다. 연구결과는 BFI값이 증가 할수록 SVI의 값은 감소하는 경향을 나타냈다. 다양한 SVI 가운데 BFI에 대한 R-B Index의 평균 결정계수가 0.66로 가장 큰 값을 나타냈으며, 특히 WHAT 모델의 Local Minimum Method(LMM)과의 결정계수가 0.82로 가장 밀접한 관계를 나타냈다. 변동계수 또한 평균 결정계수 값이 0.60으로 높은 값을 보였다. 그 외 유황계수와 Q5:Q95의 평균 결정계수는 각각 0.04와 0.07로 매우 낮은 값을 보였다. 결론적으로 다양한 SVI 가운데 R-B Index가 여러 기저유출 방법으로 산정된 BFI 값들에 대하여 가장 일관성 있는 결과를 보였다. 본 연구의 결과는 하천의 생태적 기능 유지와 치수안정성을 확보를 고려한 하천관리에 기여할 것이다.

• 지질공학
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• 제33권4호
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• pp.627-638
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• 2023

본 연구에서는 김천부항댐이 위치한 감천유역을 대상으로 댐운영에 따른 하류하천 유량의 공간적인 변동성을 평가하고자 하였다. 특히, 다목적댐의 주요기능인 치수적인 측면에서의 홍수저감과 이수적인 측면에서의 갈수기 유량확보 효과를 정량적으로 분석하였다. 대상유역에 대하여 SWAT-K 모델링을 수행하여, 댐 하류하천의 4개 수위관측지점 관측유량과 모의유량을 비교한 결과, R²와 NSE 모두 0.75 이상의 적합도를 확보하였다. 댐의 홍수저감효과의 공간적 분석을 위해 연최대 홍수량을 중심으로 분석한 결과, 4개 지점에서의 홍수저감율은 8.5~25.0%로 나타났다. 갈수기 유량확보 효과에 대해서는 유황곡선을 중심으로 평가하였으며, 특히 평균갈수량의 경우에는 33~198%의 유량증가가 이루어짐을 알 수 있었다.