Impacts of hydropeaking and thermopeaking on the downstream habitat in the Dal River, Korea

Choi, Byungwoong,Choi, Sung-Uk Elsevier 2018 Ecological Informatics Vol.43 No.-

<P><B>Abstract</B></P> <P>Dams located upstream only release water during the period of hydropower generation. This induces short-term fluctuations of water discharge in the downstream reach, which is called hydropeaking. As occurs quite often, if the temperature of the water released form the upstream dam is different from the water that is flowing in the downstream reach, the water temperature also tends to show short-term fluctuations, which is called thermopeaking. This study investigates the impacts of both hydropeaking and thermopeaking on the downstream habitat. The study area is a 2.3km long reach located downstream from the Goesan Dam in the Dal River, Korea. To assess such impacts, this study conducted physical habitat simulations. The CMS-Flow model was used for the computation of the flow and water temperature, and the GEP model for the habitat simulation. Three physical habitat variables, flow depth, velocity, and water temperature, were used. The <I>Zacco platypus</I> was selected as the target fish in the study area. Simulation results indicated that the hydropeaking flows significantly reduced both the CSI and the WUA when compared with the natural flow regime. In addition, the use of the water temperature in the physical habitat simulations further decreased both CSI and WUA, indicating that thermopeaking is as important as hydropeaking in this type of assessment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Physical habitat simulations were performed to see the impacts of hydropeaking and thermopeaking on the downstream habitat. </LI> <LI> The study area is a 2.3km long reach located downstream from the Goesan Dam in the Dal-cheon Stream, Korea. </LI> <LI> The CMS-Flow model was used to predict the flow and water temperature, and the GEP model was used for the habitat simulation. </LI> <LI> The hydropeaking flows were found to reduce both CSI and WUA significantly when compared with natural flow regime. </LI> <LI> The simulation results also indicated that the thermopeaking is as important as the hydropeaking in this type of assessment. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>This study investigated the impacts of both hydropeaking and thermopeaking on the downstream habitat. The study area is a 2.3km long reach located downstream from the Goesan Dam in the Dal River, Korea. To assess such impacts, physical habitat simulations were carried out. The CMS-Flow model was used for the computations of flow and water temperature, and the GEP model for the habitat simulation. The above figure shows the CSI distributions in the winter. In the figure, in order to investigate the impact of hydropeaking, the CSI distribution for the drought flow is provided. In addition, the CSI distributions obtained from the physical habitat simulations with and without temperature for the physical habitat variables are compared. It is found that hydropeaking operations significantly decrease the CSI when compared with the CSI distribution for the constant flow and the inclusion of the water temperature in the physical habitat simulation further decreases the CSI.</P> <P>[DISPLAY OMISSION]</P>

Prediction of local scour around bridge piers using the ANFIS method

Choi, Sung-Uk,Choi, Byungwoong,Lee, Seonmin SPRINGER INTERNATIONAL 2017 NEURAL COMPUTING AND APPLICATIONS Vol. No.

<P>Local scour around bridge piers is a complicated physical process and involves highly three-dimensional flows. Thus, the scour depth, which is directly related to the safety of a bridge, cannot be given in the form of the exact relationship of dependent variables via an analytical method. This paper proposes the use of the adaptive neuro-fuzzy inference system (ANFIS) method for predicting the scour depth around a bridge pier. Five variables including mean velocity, flow depth, size of sediment particles, critical velocity for particles' initiation of motion, and pier width were used for the scour depth. For comparison, predictions by the artificial neural network (ANN) model were also provided. Both the ANN model and ANFIS method were trained and validated. The findings indicate that the modeling with dimensional variables yields better predictions than when normalized variables are used. The ANN model was applied to a field-scale dataset. Prediction results indicated that the errors are much larger compared to the case of a laboratory-scale dataset. The MAPE by the ANN model trained with part of the field data was not seriously different from that by the model trained with the laboratory data. However, the application of the ANFIS method improved the predictions significantly, reducing the MAPE to the half of that by the ANN model. Five selected empirical formulas were also applied to the same dataset, and Sheppard and Melville's formula was found to provide the best prediction. However, the MAPEs for the scour depths predicted by empirical formulas are much larger than MAPEs by either the ANN or the ANFIS method. The ANFIS method predicts much better if the range of the training dataset is sufficiently wide to cover the range of the application dataset.</P>

Impact of Baseflow on Fish Community in the Ungcheon Stream, Korea

Choi, Byungwoong,Oh, Woo Seok,Kim, Nam Shin,Cha, Jin Yeol,Lim, Chi Hong National Institute of Ecology 2021 국립생태원회보(PNIE) Vol.2 No.4

This study investigated the impact of baseflow on fish community in the Ungcheon stream (16.5 km long) located downstream of the Boryeong Dam, Korea. Based on field monitoring, there were five dominant fish species in the Ungcheon Stream accounting for 75% of the total fish community: Zacco platypus, Zacco koreanus, Tridentiger brevispinis, Rhinogobius brunneus, and Pungtungia herzi. These five fish species were selected as target species. HydroGeoSphere (HGS) and River2D models were used for hydrologic and hydraulic simulations, respectively. A habitat suitability index model was used to simulate fish habitat. To assess the impact of baseflow, each representative discharge was examined with or without baseflow. The HGS model was used to calculate baseflow within the study reach. This baseflow was observed to increase gradually with longitudinal distance. Validation of the hydraulic model dem onstrated that computed water surface elevated when baseflow was included, which was in good agreement with measured data, as opposed to the result when baseflow was excluded. Composite suitability index distributions and weighted usable area in the study reach were presented for target species. Simulations indicated that the baseflow significantly increased habitat suitability for the entire fish community. These results demonstrate that there should be a substantial focus on the baseflow for physical habitat simulation.

AI 기법을 이용한 군집종의 물리서식처 분석

최병웅(Choi, Byungwoong),임동균(Im, Dongkyun),최성욱(Choi, Sung-Uk) 대한토목학회 2016 대한토목학회 학술대회 Vol.2016 No.10

보 수문 운영에 따른 수생 서식처 변화 연구

최병웅(Byungwoong Choi),이남주(Namjoo Lee) 응용생태공학회 2020 Ecology and resilient infrastructure Vol.7 No.4

본 연구는 다기능 보의 수문 운영 여부에 따라 수생 서식처의 변화를 파악하기 위하여 물리서식처 분석을 수행하였다. 대상 구간은 금강이며, 대상 어종은 피라미를 대상으로 하였다. 흐름 분석은 2차원 모형인 River2D 모형을 사용하였으며, 서식처 분석은 서식처 적합도 곡선을 이용하여 서식처의 양과 질을 산정하는 서식처 적합도 모형을 사용하였다. 수문 개방 여부에 따라 서식처의 변화를 살펴보기 위하여 수문 미개방과 부분개방에 대하여 설정하였다. 그 결과 수문을 부분개방하였을 때 현상태 대비 가중가용면적이 약 13배 향상되는 것으로 나타났다. This study was conducted to evaluate the impact of weir gate operation in aquatic fish habitats through a physical habitat simulation of Geum River, Korea. The target species was Zacco platypus, which is a dominant species in the study area. The River2D model was used to compute the flow, and the habitat suitability index model was used to estimate the quality and quantity of the habitat using a habitat suitability curve. An unopened case and a partially opened case were investigated to assess the impact of weir gate operation on the aquatic fish habitat. The simulation results showed that the aquatic habitats of the target species in the partially opened case improved significantly, compared to the case without a gate opening. Furthermore, the weighted usable area increased by a factor of approximately 13, owing to weir gate operation in the study area.

식생된 개수로에서의 부유사 농도 변화에 관한 수치해석

최성욱(Choi Sung-Uk),최병웅(Choi Byungwoong) 대한토목학회 2009 대한토목학회 학술대회 Vol.2009 No.10

영산강의 시공간적 수리-수질-조류 모델링 분석

최병웅(Choi, Byungwoong),강태우(Kang, Tae-Woo),박종환(Park, Jonghwan),신동석(Shin, Dong-Seok),최지연(Choi, Jiyeon) 대한토목학회 2022 대한토목학회 학술대회 Vol.2022 No.10

비점오염원 관리를 위한 영산강유역의 오염하천 목록 설정 연구

최지연 ( Choi Jiyeon ),최병웅 ( Choi Byungwoong ),이영재 ( Lee Youngjea ),신동석 ( Shin Dong-seok ) 한국물환경학회 2022 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2022 No.-

여울-소 출현 복원을 통한 다양한 어종의 서식처 변화 연구

최흥식(Heung Sik Choi),최종근(Jonggeun Choi),최병웅(Byungwoong Choi) 응용생태공학회 2020 Ecology and resilient infrastructure Vol.7 No.1

본 연구는 복원기법을 다양하게 조성하였을 때 어류의 서식처의 변화를 파악하기 위하여 물리서식처 모의를 수행하였다. 대상 구간은 원주천이며, 대상 어종은 돌고기, 피라미, 참갈겨니를 대상으로 하였다. 흐름 분석은 2차원 모형인 River2D 모형을 사용하였으며, 서식처 분석은 서식처 적합도 곡선을 이용하여 서식처의 양과 질을 산정하는 서식처 적합도 모형을 사용하였다. 생태학적으로 적합한 여울-소 출현에 따른 서식처의 변화를 확인하기 위하여 조성 구간을 50 m, 100 m, 200 m, 300 m으로 설정하였다. 그 결과 대상 어종별로 약간의 차이는 발생하였지만, 여울-소 복원기법을 200 m 구간으로 설정하였을 때 서식처가 현상태와 비교하였을 때 가중가용면적이 약 53% 향상되는 것으로 나타났다. The present study aimed to investigate the impact of the restoration of the restoration technique on fish habitat using a physical habitat simulation in the Wonju-cheon Stream, Korea. The target species were Pungtungia herzi, Zacco platypus, and Zacco Koreanus, a dominant and sub-dominant species in the Wonju-cheon Stream. The River2D model was used for the computation of the flow and the habitat suitability index model was used to estimate the quality and quantity of habitat using habitat suitability curve. To assess the impact of pool-riffle sequence on change of fish habitat, this present study conducted using the each representative distance, namely, 50 m, 100 m, 200 m, and 300 m. Simulation results indicated that the pool-reffle sequence significantly increased the habitats for the target species than the result without considering pool-riffle sequence. On average, 53% of the Weighted Usable Area (WUA) increased due to pool-riffle sequence in the study area.

Stable Carbon Isotope Signature of Dissolved Inorganic Carbon (DIC) in Two Streams with Contrasting Watershed Environments: A Potential Indicator for Assessing Stream Ecosystem Health

Kim, Chulgoo,Choi, Jong-Yun,Choi, Byungwoong,Lee, JunSeok,Jeon, Yonglak,Yi, Taewoo National Institute of Ecology 2021 국립생태원회보(PNIE) Vol.2 No.4

We conducted a study to investigate the characteristics of the carbon cycle of two streams (located in Shig a Prefecture, Japan), having similar size, namely, the Adokawa stream (length: 52 km, area: 305 km², watershed population: 8,000) and the Yasukawa stream (length: 62 km, area: 380 km², watershed population: 120,000), but with different degree of human activity. Samples were collected from these two streams at 14 (Adokawa stream) and 23 (Yasukawa stream) stations in the flowing direction. The dissolved inorganic carbon (DIC) concentration and the stable carbon isotope ratio of DIC (δ¹³C-DIC) were measured in addition to the watershed features and the chemical variables of the stream water. The δ¹³C-DIC (-9.50 ± 2.54‰), DIC concentration (249 ± 76 µM), and electric conductivity (52 ± 13 µS/cm) in Adokawa stream showed small variations from upstream to downstream. However, the δ¹³C-DIC (-8.68 ± 2.3‰) upstream of Yasukawa stream was similar to that of Adokawa stream and decreased downstream (-12.13 ± 0.43‰). DIC concentration (upstream: 272 ± 89 µM, downstream: 690 ± 37 µM) and electric conductivity (upstream: 69 ± 17 µS/cm, downstream: 193 ± 37 µS/cm) were higher downstream than upstream of Yasukawa stream. The DIC concentration of Yasukawa stream was significantly correlated with watershed environmental variables, such as, watershed population density (r = 0.8581, p<0.0001, n = 23), and forest area percentage of the watershed (r = -0.9188, p<0.0001, n = 23). δ¹³C-DIC showed significant negative correlation with the DIC concentration (r = -0.7734, p<0.0001, n = 23), electric conductivity (r = -0.5396, p = 0.0079, n = 23), and watershed population density (r = -0.6836, p = 0.0003, n = 23). Our approach using a stable carbon isotope ratio suggests that DIC concentration and δ¹³C-DIC could be used as indicators for monitoring the health of stream ecosystems with different watershed characteristics.