• Title, Summary, Keyword: Juksan Weir

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Analysis of Environmental Factors Associated with Cyanobacteria Dominance in Baekje Weir and Juksan Weir (백제보와 죽산보에서 남조류 우점 환경요인 분석)

  • Kim, Sung-Jin;Chung, Se-Woong;Park, Hyung-Seok;Cho, Young-Cheol;Lee, Hee-Suk;Park, Yeon-Jeong
    • Journal of Korean Society on Water Environment
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    • v.35 no.3
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    • pp.257-270
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    • 2019
  • Followingthe Four Rivers Project, cyanobacterial blooms have been frequently observed in the upstream of the installed weirs. The aim of this study was to characterize the major environmental factors that are associated with the cyanobacteria dominance in Baekje Weir (Geum River) and Juksan Weir (Youngsan River) based on intensive experiments and systematic data mining methods. The factors related to the cyanobacteria dominance include7-days cumulative rainfall (APRCP7), 7-days averaged flow (Q7day), water temperature (Temp), stratification strength (${\Delta}T$), electronic conductivity (EC), DO, pH, $NO_3-N$, $NH_3-N$, TN, TP, $PO_4-P$, Chl-a, Fe, BOD, COD, TOC, and $SiO_2$. The most highly correlatedfactors to the dominant cyanobacteria were found to be EC, Temp, Q7day, $PO_4-P$ in theBaekje Weir. On the other hand, those dominant in the Juksan Weir were ${\Delta}T$, TOC, Temp, EC and TN. The EC showed a strong correlation with cyanobacteria dominance in both weirs because a high EC represents a persisted low flow condition. The cyanobacteria dominance was as high as 56 % when the EC was equal or greater than $418{\mu}S/cm$ in Baekje Weir. It was as high as 63% when the ${\Delta}T{\geq}2.1^{\circ}C$ in the Juksan Weir. However, nutrients showed a minor correlation with cyanobacteria dominance in both weirs. The results suggest that the cyanobacteria dominate in astate where the water flow rate is low, water temperature is high and thermal stratification is strengthened. Therefore, the improvement of flow regimes is the most important to prevent persistent thermal stratification and formation of cyanobacteria bloom in theBaekje and JuksanWeirs.

Chemical Water Quality and Fish Component Analyses in the Periods of Before- and After-the Weir Constructions in Yeongsan River

  • Kwak, Sang Do;Choi, Ji-Woong;An, Kwang-Guk
    • Journal of Ecology and Environment
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    • v.39 no.1
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    • pp.99-110
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    • 2016
  • The objective of this study was to analyze chemical water quality, ecological characteristics of fish compositions, and ecosystem health before- (Bwc; 2008-2009) and after-the weir construction (Awc; 2011-2012) at Juksan Weir and Seungchon Weir of Yeongsan River watershed. Suspended solids (SS) and chlorophyll-a (Chl-a) in Juksan Weir increased, whereas nutrients such as total nitrogen (TN) and total phosphorus (TP) decreased in the epilimnetic water. In Juksan and Seungchon weirs, fish species distribution analysis in the periods of Bwc and Awc showed that sensitive species were rare and tolerant species were dominant in the community. In the analysis of trophic guild, relative abundance of carnivore species are increased to 22% and 12%, respectively, after the constructions of Seungchon Weir and Juksan Weir. Mann-Whitney U-tests of nonparametric statistical analysis indicated that omnivore and carnivore species had significant differences (p < 0.05) between the Bwc and Awc. The massive population growth of an exotic species, Micropterus salmoides, was evident in Seungchon Weir to influence on the structures of fish communities. The model values of mean Index of Biological Integrity (IBI), based on fish assemblages, were < 15, which indicates "poor" condition in the river health, and the significant difference of IBI values was not found between the Bwc and Awc.

The Evaluations of Fish Survival Rate and Fish Movements using the Tagging Monitoring Approach of Passive Integrated Transponders (PIT) (수동형 전자발신장치(Passive Integrated Transponder, PIT) 모니터링 기법 적용에 따른 어종별 생존율 평가 및 어도에서 어류이동성 평가)

  • Choi, Ji-Woong;An, Kwang-Guk
    • Journal of Environmental Science International
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    • v.23 no.8
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    • pp.1495-1505
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    • 2014
  • The objective of this study was to evaluate survival rate and fish movement (migration) using a tagging approach of passive integrated transponder (PIT) in Juksan Weir, which was constructed as a four major river restoration projects. For this study, survival rates of each fish species and the mobility of fish individuals were analyzed during 2 weeks by the insertion of PIT tags to various fish species in the laboratory. According to tagging tests in the laboratory, the survival rate 37.5% (30 survivals of 80 individuals) after the insertion of PIT tags. The survival rate of Carassius auratus and Hemibarbus labeo was 100% and 80% after the insertion of the tags, respectively, whereas it was only 13.3% for Zacco platypus. In the field experiments of Juksan Weir, 6 species and 157 individuals from 8 species (563 individuals) were detected in the fixed automatic data-logging system, indicating a detection rate of 27.9% in the fishway of Juksan Weir. In the meantime, some species with no or low detection rates in the fixed automatic data-logging system were turn out to be stagnant-type species, which prefer stagnant or standing water to live.

Analyzing the Effect of a Weir Construction on the Groundwater Flow System (보 건설이 주변지역 지하수 흐름계에 미치는 영향)

  • Jeong, Soo-Jeong;Koo, Min-Ho
    • Journal of Soil and Groundwater Environment
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    • v.17 no.3
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    • pp.39-48
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    • 2012
  • Visual MODFLOW, a three dimensional groundwater flow model, was used to analyze effects of a weir construction in an alluvial stream on the nearby groundwater flow system. A hypothetical conceptual model was developed to investigate how the groundwater level and the water budget could change after a weir construction depending on the location of tributary streams. A site example, dealing with the Juksan weir installed in the Yeongsan River, was also demonstrated to predict the effects of the weir construction. Model results show that impacts of a weir construction on the groundwater flow system greatly vary depending on how far a tributary is located and whether it is located downstream or upstream from the weir. Therefore, consideration of the location of tributaries in planning the location of a weir could effectively minimize the impacts of a weir construction on the groundwater flow system. It is also demonstrated that model results are highly dependent upon how the model is dealing with small tributaries and agricultural drainage channels, which can be easily found nearby the main streams, acting as major water bodies for groundwater discharge. The model for the Juksan area shows that the weir construction will change the direction of groundwater flow in some areas, leading to changes of groundwater quality and interaction of the Yeongsan River to the aquifer from a gaining to a losing stream. The model also predicted the areas where rise of groundwater level caused by the Juksan weir could adversely affect plant growth, and thereby suggested installing new drainage channels as a countermeasure to drawdown the groundwater level.

Fish Passage Assessments in the Fishway of Juksan Weir Constructed in the Downstream Area of Youngsan-River Watershed (영산강수계의 죽산보에 설치된 어도에서 어류의 이동성 평가)

  • Park, Chan-Seo;An, Kwang-Guk
    • Journal of Environmental Science International
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    • v.23 no.8
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    • pp.1513-1522
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    • 2014
  • Fish passage asssessments were conducted in the fishway at Juksan Weir, which was constructed as a four-major rivers project in the downstream area of Youngsan-River Watershed. For the research, fish-movements/migrations were analyzed for seven times from April ~ October, 2013 using an approach of fish trap-setting. Fish fauna and compositions were analyzed in the fishway, and seasonal- and diel-movement patterns were analyzed in relation to current velocity in the fishway. Also, abundances of exotic fishes such as bluegill sunfish (Lepomis macrochirus), large-mouth bass (Micropterus salmoides), and white curcian carp (Carassius cuvieri) were monitored in the fishway. Current velocity(n = 18) in the fishway showed large variations ($0.82{\pm}0.63m/s$) depending on the location of the fish trap-setting and this physical factor influenced the fish movements. Fish movements, based on the CPUE of individuals, in the fishway was greater in slower velocity (mean: 0.36 m/s, range: 0.10~1.54 m/s) than faster velocity (mean: 1.51 m/s, range: 0.90~1.90 m/s). Seasonal analysis of fish movements showed that most frequent uses (8 speices and 591 individuals, 66.2% of the total) of the fishway occurred in spring period(i.e., June). Diel movement analysis, in the mean time, showed highest in the time period of 00:00 ~ 3:00 am (7 species and 281 individuals, 20.9% of the total). The efficient managements in the fishway at Juksan Weir are required in relation to the hydrological regime.

Effect of major pollution sources on algal blooms in the Seungchon weir and Juksan weir in the Yeongsan River using EFDC (EFDC를 이용한 영산강 주요 오염 부하 저감에 따른 승촌보 및 죽산보 녹조 현상 개선 효과 분석)

  • Kim, Jinsoo;Kim, Jaeyoung;Seo, Dongil
    • Journal of Korea Water Resources Association
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    • v.53 no.5
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    • pp.369-381
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    • 2020
  • In this paper, observed water quality, algal blooms and flow rates in the Yeongsan River and its boundaries including 8 tributaries and 2 wastewater treatment plants for two years of 2018-2019 were analyzed. It seems effects of non-point source load inputs from basin areas to the river may be significant though the field data availability was limited. The EFDC model was calibrated against data collected from 6 water level monitoring stations and 6 water quality monitoring stations, respectively, in the study area. Water quality improvement scenarios were developed assuming 50% and 75% reductions of major pollution sources including treatment plants and tributaries. The developed scenarios were applied to the EFDC model to estimate effects on algal bloom occurrences in the Seungchon weir and Juksan weir. Improvement of the effluent of Gwangju 1 WWTP by 75% did not show any effect on algal blooms for two weir locations. The major tributary affecting algal blooms in the Seungchon weir was the Hwangryong River. The Jisuk stream was found as the most important tributary for the Juksan weir followed by the effect of the Hwangryong River. Though it seems other scattered small nonpoint source load input to the Yeongsan river also seem to be important, it was not possible to reflect their effects appropriately due to field data availability.

Development of Fishway Assessment Model based on the Fishway Structure, Hydrology and Biological Characteristics in Lotic Ecosystem

  • Choi, Ji-Woong;Park, Chan-Seo;An, Kwang-Guk
    • Journal of Ecology and Environment
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    • v.39 no.1
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    • pp.71-80
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    • 2016
  • The main goal of this study is to develop a multi-metric fishway assessment model (Mm-FA) and evaluate the efficiency of fishway. The Mm-FA model has three major fishway components with nine metrics: structural characteristics, hydraulic/hydrologic features, and biological attributes. The model was developed for diagnosing and assessing fishway efficiency and tested to Juksan Weir at the Yeongsan River Watershed. Structural characteristics of fishway included slope of the fishway (M1), ratios of fishway width to stream width (M2), and the proportion of orifice clogging and orifice size (M3). Hydraulic/hydrologic characteristics included depth of fishway entrance head (M4), depth of exit tail (M5), and current velocity of inner fishway (M6). Biological characteristics included fish species ratio of inner fishway to upper-lower weir (M7), fish length distribution (M8), and the proportion of migratory fish species to the total number of species (M9). Overall, the assessment of fishway efficiency showed the total score of the Mm-FA model was 25 in the Juksan Weir, indicating "good condition" by the criteria of the five-level classification system. The Mm-FA model may be used as a key tool for the assessment of fishway efficiency, especially on the 16 weirs constructed for the "Four Rivers Restoration Project" after a partial calibration of Mm-FA model.

Prediction of short-term algal bloom using the M5P model-tree and extreme learning machine

  • Yi, Hye-Suk;Lee, Bomi;Park, Sangyoung;Kwak, Keun-Chang;An, Kwang-Guk
    • Environmental Engineering Research
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    • v.24 no.3
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    • pp.404-411
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    • 2019
  • In this study, we designed a data-driven model to predict chlorophyll-a using M5P model tree and extreme learning machine (ELM). The Juksan weir in the Youngsan River has high chlorophyll-a, which is the primary indicator of algal bloom every year. Short-term algal bloom prediction is important for environmental management and ecological assessment. Two models were developed and evaluated for short-term algal bloom prediction. M5P is a classification and regression-analysis-based method, and ELM is a feed-forward neural network with fast learning using the least square estimate for regression. The dataset used in this study includes water temperature, rainfall, solar radiation, total nitrogen, total phosphorus, N/P ratio, and chlorophyll-a, which were collected on a daily basis from January 2013 to December 2016. The M5P model showed that the prediction model after one day had the highest performance power and dropped off rapidly starting with predictions after three days. Comparing the performance power of the ELM model with the M5P model, it was found that the performance power of the 1-7 d chlorophyll-a prediction model was higher. Moreover, in a period of rapidly increasing algal blooms, the ELM model showed higher accuracy than the M5P model.

Characteristics of Nitro-nutrients and Phytoplankton Dynamics in the Yeongsan River after Weir Construction (보 건설 이후 영산강 보 구간에서의 질소계열 영양염류 및 식물플랑크톤 동태)

  • Seo, Kyung-Ae;Na, Jeong-Eun;Ryu, Hui-Seong;Kim, Kyunghyun
    • Journal of Korean Society on Water Environment
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    • v.34 no.4
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    • pp.423-430
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    • 2018
  • Insomuch as it is important to manage water quality, from the perspective of water management, it is essential to understand the effect of the weirs on water quality and phytoplankton dynamics in various regions. The purpose of this study is to investigate the characteristics of nitro-nutrients, as well as occurrences and succession patterns of phytoplankton, in the river sections of the two weirs in the Yeongsan River for the five years (from 2012 to 2016) after the weir construction. In respect to this data, the average water temperature measured at the representative point in the section of the Seungchon Weir ($17.1^{\circ}C$) was higher than that of the Juksan Weir ($16.6^{\circ}C$) by comparison. By way of an analysis of this data, it was found that the water quality variables such as, organic matter, nitrogen nutrients and phosphorus nutrients were improved gradually during the period, but the degree of the improvement differs as noted and measured between the weirs. Under the circumstances, it is especially noted that the $NH_3-N$ concentration was higher for the point of the Seungchon Weir (2.204 mg/L) than that of the Juksan Weir (1.157 mg/L). This indicates that effluent as seen from sewage treatment plants and hydrological feature near the densely population area, could be the main cause for the incidence of water pollution in the upstream section of the Seungchon Weir. Additionally, the phytoplankton analysis showed that a relative abundance of diatoms and green algae were 56.9 % and 25.8 % respectively. However, it is noted that the cyanobacteria was measured lower as 10.7 %. Also, in the study sites cell density and occurrence frequency of cyanobacteria were relatively lower than compared to the same measurements noted in other rivers.

Summer Patterns and Diel Variations of Fish Movements Using Fish Trap Sampling Technique in the Juksan Weir (죽산보의 어도에서 트랩 샘플링 기법을 이용한 하절기, 일주기별 어류 이동성 평가)

  • Han, Jeong-Ho;Ko, Dae-Geun;Lim, Byung Jin;Park, Jong-Hwan;An, Kwang-Guk
    • Journal of Environmental Impact Assessment
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    • v.21 no.6
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    • pp.879-891
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    • 2012
  • The objective of this study was to evaluate seasonal patterns and diel variations of fish movements in the Juksan Weir which was constructed in 2010 at the down-stream of Yeongsan-River watershed. For this study, we monitored day-and-night movement(24 Hr cycle) and seasonal fish migration(June ~ August) patterns in 2011 along with species compositions and abundances depending on the locations of the traps within the fishway. Total number of species sampled was 14 and the total number of individuals was 1,263 with only the size-fractions(as total length) of the fish < 20 cm during the study. Seasonal analysis of fish movement in the fish way showed that highest frequency in the movement occurred in June - July, which is closely associated with a spawning peak season. The most dominant species using the fishway was Squalidus chankaensis tsuchigae, and this species turned out to be 26.9% of the total in the use rate of fishway. Daily monitoring of fish movements showed that most frequent movements occurred between 18:00 PM and 21:00 PM when the fish have a feeding time generally. The migratory fish were not found in the fishway during the study. Mean current velocity during the study $0.42{\pm}0.02ms^{-1}$(n = 42), and there were no significant statistical differences(p > 0.05) among the daily and monthly velocities in the fishway. The use rate of fish passage, in terms of fish species, was 48%, compared with total sampling of fish species(29 species) at the down-river regions during the same period, indicating a low use rate. Further continuous long-term monitoring should be conducted to evaluate the impacts of the weir construction in the river.