• Title/Summary/Keyword: Nakdong River Estuary

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Study on Water Level and Salinity Characteristics of Nakdong River Estuary Area by Discharge Variations at Changnyeong-Haman Weir(1) (창녕·함안보 방류량에 따른 하류지역 및 하구역의 수리환경특성에 관한 연구(1))

  • Kim, Tae-Woo;Yang, Hyun-Soo;Park, Byeong-Woo;Yoon, Jong-Sung
    • Journal of Ocean Engineering and Technology
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    • v.32 no.5
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    • pp.361-366
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    • 2018
  • The present study analyzed the variation factors in inducing a salinity change using the existing observation network in the section between the Nakdong River Estuary Barrage and Changnyeong-Haman Weir, and also examined the seasonal changes in precipitation, salinity, and discharge. Furthermore, this study analyzed the causes of a salinity increase by collecting observational data during a period when abnormal salinity occurred, and further investigated the salinity transfer time in a section of approximately 5.3 km from the Nakdong River Estuary Barrage to Nakdong River Bridge to understand the behavioral characteristics of the salinity moving upstream. The study results would make it possible to control the increase in salinity and block salt water from moving upstream by understanding the salinity variation characteristics according to the discharge amount. This will provide stability in collecting water from various residential, agricultural, and industrial sources through water intake facilities scattered near the Nakdong River Estuary Barrage.

The Analysis of Inflowing Sediments Behavior around the Sandbar in Nakdong River Estuary (낙동강 하구역 사주 주변에서의 퇴적물질의 유압거동 해석)

  • KIM KYUNG-HOI;LEE IN-CHEOL
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2004.11a
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    • pp.133-136
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    • 2004
  • In-situ collection experiments were performed to analyze inflowing sedilnents behavior as a basic study of topographical change in Nakdong River Estuary. Sediment rate and bed load flux ranged from 0.0004 to $0.472\;g/cm^2/day\;and\;0.0005\~1.7579\;g/cm^2/day$, respectively. The settling velocity of suspended particulate matter was estimated in tire range of $0.339\~1.010\;cm/sec$, The grain size analysis shows that surface sediments in backside of sandbar and bed load in front of dike have a similar grain size distribution. It is considered that the source of surface sediments in backside of sandbar were flowed in from Nakdong River. In order to verify the characteristics of inflowing sediments behavior, detailed surveys around Nakdong River Estuary need to be carried out, continuously.

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Using the Contingent Valuation Method Based on Multi-attribute Utility Theory to Measure the Environmental Value of the Nakdong-river Estuary (다속성 효용이론에 근거한 조건부 가치측정법을 이용한 낙동강 하구의 환경가치 추정)

  • Yoo, Seung-Hoon
    • Ocean and Polar Research
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    • v.29 no.1
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    • pp.69-80
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    • 2007
  • This paper attempts to measure the environmental value of the Nakdong-river estuary, which is ecologically important but confronted with the threat of development. Especially, in order to elicit the environmental values of its four attributes, contingent valuation method(CVM) based on multi-attribute utility theory is applied and the CVM survey was rigorously designed to comply with the guidelines for best-practiced CVM studies. We surveyed a randomly selected sample of 400 and 350 households in Busan and six large cities(Seoul, Incheon, Daegu, Daejeon, Gwangju, and Ulsan), respectively and asked respondents questions in person-to-person interviews about how they would willing to pay for the estuary conservation and management program. Respondents overall accepted the contingent market and were willing to contribute a significant amount(2,457 won in Busan and 3,560 won in six large cities), on average, per household per year, which implies that there exists a large difference between the two. The aggregate values of the Nakdong-river estuary in Busan and six large cities amount to 2.92 and 22.32 billion won, respectively, per year. In addition, expanding the values to Korea produces 51.34 billion won per year. The quantitative values can be utilized in planning and decision-making about development versus conservation of the estuary.

Measurements of $^{224}Ra\;and\;^{223}Ra$ in the Nakdong River estuary and the South Sea of Korea

  • Hwang, Dong-Woon;Kim, Gue-Buem;Yang, Han-Soeb
    • Journal of the korean society of oceanography
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    • v.38 no.2
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    • pp.80-86
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    • 2003
  • The horizontal distributions of $^{224}Ra$ (half life=3.4 days) and $^{223}Ra$ (half life=11.3 days) were measured in surface seawaters of the Nakdong River estuary and the South Sea of Korea in April and October 2002. In order to determine these short-lived Ra isotopes, we used a delayed coincidence counter which is much more rapid and accurate than traditional methods. In an estuarine mixing zone (salinity, ~l6 ppt), the activities of $^{224}Ra\;and\;^{223}Ra$ were much greater than what would be expected from a mixture of freshwater and seawater in the Nakdong River estuary. This excess Ra may be a result of Ra desorption from fresh sediments originating from the river upstream. However, in the more open areas of the Nakdong River estuary (salinity>30 ppt) and the South Sea of Korea, $^{224}Ra\;and\;^{^{223}Ra$ activities decreased exponentially as a function of distance offshore. Using the decrease of $^{223}Ra$ with distance offshore in the South Sea of Korea, we estimated the apparent horizontal eddy diffusivities. The apparent eddy diffusion coefficients in South Sea of Korea are calculated to be approximately $3500-8000\;\textrm{m}^2/sec$.

Prediction of DO Concentration in Nakdong River Estuary through Case Study Based on Long Short Term Memory Model (Long Short Term Memory 모델 기반 Case Study를 통한 낙동강 하구역의 용존산소농도 예측)

  • Park, Seongsik;Kim, Kyunghoi
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.33 no.6
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    • pp.238-245
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    • 2021
  • In this study, we carried out case study to predict dissolved oxygen (DO) concentration of Nakdong river estuary with LSTM model. we aimed to figure out a optimal model condition and appropriate predictor for prediction in dissolved oxygen concentration with model parameter and predictor as cases. Model parameter case study results showed that Epoch = 300 and Sequence length = 1 showed higher accuracy than other conditions. In predictor case study, it was highest accuracy where DO and Temperature were used as a predictor, it was caused by high correlation between DO concentration and Temperature. From above results, we figured out an appropriate model condition and predictor for prediction in DO concentration of Nakdong river estuary.

Delta Development in the Nakdong River Estuary: a Literature Survey (낙동강 하구역 삼각주 발달에 관한 문헌 고찰 연구)

  • Yoon, Han-Sam;Yoo, Chang-Ill;Kang, Yoon-Koo;Ryu, Cheong-Ro
    • Journal of Ocean Engineering and Technology
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    • v.21 no.2 s.75
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    • pp.22-34
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    • 2007
  • We present basic data for developing new research topics and closely examine the existing data on the development and organization of the Nakdong River Estuary Delta by analyzing various studies of the area, including ocean engineering, coastal engineering, ocean environmental engineering, geomorphological, and geological studies. We first defined the general concepts related to the estuary and delta and reviewed the historical development of the Nakdong River Estuary Delta over the past 100 years. We then examined the origin and core elements of the estuary deposits that constitute the delta. In addition, we scrutinized the main factors affecting the development of the delta and analyzed existing research on delta development mechanisms by core researchers. The construction of an estuary barrage is one of the main factors effecting estuarine circulation and has altered the physical oceanic environment, area of deposition, atmospheric environment, and vegetation community of the delta. These factors affect the estuary circulation in turn, altering the delta. Along the Nakdong River, an unsteady-state sandy barrier appears at approximately three times the distance of the wavelength of incident offshore waves, and this terrain forms approximately 10-15 years after reclamation in the interdistributary upper stream and transforms the shoreline. It is necessary to develop a technique to predict terrain change that reproduces the erosion and accumulation of estuarine deposits. To determine the parameters and variables necessary to reproduce this system, continuous on-site monitoring is necessary. The existing research did not fully examine the terrain changes in Nakdong River Estuary or the periodic developmental characteristics. To understand the future process of estuary delta development, it is necessary to establish an integrated management system.

Effects of Meteorological and Oceanographic Properties on Variability of Laver Production at Nakdong River Estuary, South Coast of Korea (낙동강 하구 해양환경 및 기상 요인이 김P(orphyra yezoensis) 생산량 변화에 미치는 영향)

  • Kwon, Jung-No;Shim, JeongHee;Lee, Sang Yong;Cho, Jin Dae
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.46 no.6
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    • pp.868-877
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    • 2013
  • To understand the effects of marine environmental and meteorological parameters on laver Porphyra yezoensis production at Nakdong River Estuary, we analyzed marine environmental (water temperature, salinity, nutrients, etc.) and meteorological properties (air temperature, wind speed, precipitation, sunshine hours) with yearly and monthly variations in laver production over 10 years (2003-2013). Air and water temperature, wind speed, sunshine hours and precipitation were major factors affecting yearly variability in laver production at the Nakdong River Estuary. Lower air and water temperatures together with higher levels of nutrients and sunshine and stronger wind speeds resulted in higher laver harvests. Salinity and nitrogen did not show clear correlations with laver production, mainly due to the plentiful supply of nitrogen from river discharge and the low frequency of environmental measurements, which resulted in low statistical confidence. However, environmental factors affecting monthly laver production were related to the life cycle (culturing stage) of Porphyra yezoensis and were somewhat different from factors affecting annual laver production. In November, a young laver needs lower water temperatures for rapid growth, while a mature laver needs much stronger winds and more sunshine, as well as lower temperatures for massive production and effective photosynthesis, mostly in December and January. However, in spring (March), more stable environments with fewer fluctuations in air temperature are needed to sustain the production of newly deployed culture-nets ($2^{nd}$ time culture). These results indicate that rapid changes in weather and marine environments caused by global climate change will negatively affect laver production and, thus, to sustain the yield of and predict future variability in laver production at the Nakdong River estuary, environmental variation around laver culturing farms needs to be monitored with high resolution in space and time.

Evaluation of Water Quality using Principal Component Analysis in the Nakdong Rivev Estuary (주성분 분석법을 이용한 낙동강 하구 해역의 수질 평가)

  • Sin, Seong-Gyo;Park, Cheong-Gil;Song, Gyo-Uk
    • Journal of Environmental Science International
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    • v.7 no.2
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    • pp.171-176
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    • 1998
  • This study was conducted to evaluate water quality utilizing principal component analysis in the Nakdong River Estuary. From the results of analysis, water quality in the Nakdong River Estuary could be explained up to 65.3 Percente by three factors which were Included In river loadlnwastes from the Nakdong River and rainfalls : 39.1%1, sediment resuspension(13.7BS) and metabolism(12.5%). In the eastern part of estuary In flowing the Nakdong River, river loading factor score(factor 1 Pas higher than that In western part. Sediment resuspension factor score(factor 2) was high in shallow water, while metabolism factor score(factor 3) was high in deeper water. For seasonal variations of factors score, factor 1 was h19h- 1y related to rainfall season.

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Grain size distribution of sediment around Jinudo in Nakdong River Estuary (낙동강 진우도 주변 해역의 모래입도 분포)

  • Yoo, Chang-Ill;Yoon, Han-Sam;Lee, In-Cheol;Ryu, Cheoung-Ro
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2006.11a
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    • pp.441-444
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    • 2006
  • Nakdong river estuary is located at south-eastern coast if the Korea. Especially, Complicating topography change is generated by interaction of much sediment, wave and tide. This study is investigated into observation data of grading size distribution in the post and surface sediment characteristics is investigated into grading size analysis using sieve analysis in Nakong river estuary. As a result, mean diameter of surface sediment is distributed to front of shoal as a size with 0.1~0.2 mm and mean diameter of the last generated shoal is about 0.2~0.3 mm.

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Morphological Change in Seabed Surrounding Jinwoo-Island Due to Construction of New Busan Port - Qualitative Evaluation through Numerical Simulation (부산신항 건설이 진우도 주변 해저지형 변화에 미치는 영향 - 수치실험을 통한 정성적 평가)

  • Hong, Namseeg
    • Journal of Ocean Engineering and Technology
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    • v.32 no.3
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    • pp.192-201
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    • 2018
  • In this study, a qualitative evaluation of the morphological changes in the seabed surrounding Jinwoo-Island due to the construction of the new Busan port were determined through a numerical simulation. Various scenarios for the discharge of the Nakdong river estuary dam and construction stage of the new Busan port were established and utilized for an indirect and qualitative investigation through simulation using the numerical model implemented in this study. It was concluded through a qualitative study that the morphological changes in the seabed surrounding Jinwoo-Island were typical estuary seabed changes due to the discharge of the Nakdong river estuary dam and waves from the open sea. The effects from the construction of the new Busan port were relatively small.