• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.22 no.4
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• pp.172-186
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• 2017

Current study is a part of the efforts to assess the estuarine barrage effects on the coastal ecosystem induced by the Si flux changes. Surface sediments from Seomjin and Nakdong estuary and sediment cores from Nakdong estuary was analysed to investigate the effect of estuarine barrage on the distribution of grain size, organic matter (loss on ignition: LOI) and biogenic silica (BSi). The samples of Seomjin estuary were collected in March, 2015 and those of Nakdong estuary were collected in November, 2014. Generally, the longitudinal distribution of grain size, LOI and BSi in Seomjin estuary, natural estuary, was gradually changed. However mud (silt and clay), LOI and BSi increased from station mid-estuary where tide reaches year-round. The distribution of grain size, LOI and BSi in Nakdong estuary, however, were entirely different between inside and outside of estuarine barrage. The mud percentage and LOI were low and consistent in inside of the barrage except R05, inside of right gate, yet those of outside of the barrage were higher and varied by adjacent sluices. Mud, LOI and BSi of ND1 and ND2 decreased immediately after the construction of Nakdong estuarine barrage due to disturbance of sediment and decrease of sediment supply. To exclude the physical effects by the barrage, BSi excess ($BSi_{exc}$) was calculated using regression equation of BSi-LOI and BSi-mud of Seomjin estuary. $BSi_{exc}$ of Seomjin estuary decreased gradually from upper estuary to lower estuary. $BSi_{exc}$ of Nakdong estuary were positive in inside of the barrage and negative in outside of the barrage. BSi retention and shift of species composition of diatom by the barrage would affect $BSi_{exc}$ distribution. Before the construction of Nakdong estuarine barrage, $BSi_{exc}$ of ND2 was negative and consistent owing to high mud sedimentation. After the construction, $BSi_{exc}$ of ND2, however, fluctuated due to continuous disturbance of sediment due to construction of Eulsuk bridge and East gate.

• Proceedings of KOSOMES biannual meeting
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• 2007.11a
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• pp.23-28
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• 2007

This study estimated the behavior(movement) characteristics of floating marine debris flowing in the Nakdong River Estuary using a simple numerical particle-tracking model. This numerical experiment considered the maximum water discharge outflow from the Nakdong River barrage during the passage of typhoon Maemi in 2003. The simulation showed that the particle distribution and movement of floating marine debris in the Nakdong River Estuary reached a stable state at 72 hours after the typhoon had passed, during the flαxl period of river discharge. The quantity of floating particles distributed on the east coast of Gadeok and Jinu Islands increased by 40% at 33 hours after starting the model, while the change in other sea areas was $20{\sim}40%$.

• Journal of Wetlands Research
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• v.12 no.1
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• pp.83-94
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• 2010

Purpose of this study is to define the wise use of Nakdong River estuary based on the expert's survey aiming to identify the core conservation area, the buffering area and the transition area of the estuary. The boundary of the each area is determined by overlaying the expert's opinion of the conservation area, the Biotop conservation value evaluation carried out by Busan Metropolitan city and the designated legal boundary of conservation such as Cultural Reserve area and Wetland Reserve area. Then the concept for wise use of the core preservation area, the buffering area and the transition area is set by the discussion, brainstorming and several workshops. We believe this research leads the sustainable development in the area of the Nakdong River estuary and helps to minimize the conflict among the stakeholders.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.21-22
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• 2020

낙동강 하굿둑(이하 하굿둑)은 1987년 부산 사하구와 강서구 사이에 건설되어 하류 지역의 바닷물 유입을 막아 부산, 울산, 경남 등에 안정적으로 생활·농업·공업 등의 분야에 용수를 공급하는 역할을 해왔다. 현재, 하굿둑의 수문은 낙동강 상류로부터 하류로 흘러내려오는 민물(담수)을 방류하기 위해서만 하굿둑 수문을 개방하고 있다. 하구는 하천의 담수와 바다의 염수가 서로 만나는 구역으로 바닷물과 염수의 밀도차에 의한 혼합으로 자연상태의 하구에서는 담수와 염수가 섞이는 기수역이 형성되며, 이러한 특성으로 하구 인근의 지역에서는 일반적인 하천 및 해양, 연안과는 분명히 구별되는 생태계가 조성된다. 하굿둑 건설이후 바닷물(해수)과 민물(담수)이 만나는 낙동강 어귀에 기수생태계가 사라지면서 바닷물이 유입될 수 있도록 하여 생태계를 복원해야 한다는 필요성이 제기되어 왔으며, 하굿둑이 지역에 기여해온 사실은 분명하나 하굿둑으로 인해 생태계 단절이 발생하고 기수생태계가 파괴되었기 때문에 이를 해결하기 위해서는 하굿둑을 개방하여 과거 기수생태계를 복원해야 한다는 목소리가 높아지고 있다. 이에 따라 정부에서는 하굿둑의 기수생태계 복원을 위해서 관계기관 합동으로 의사결정을 하고 효율적인 개방 방안을 모색하는 실무협의회를 구성하여 운영 중이고, 실무협의회 논의를 통해 5개 주요 관계기관(환경부, 국토부, 해양수산부, 부산광역시, K-water) 공동으로 "낙동강하굿둑 운영개선 및 생태복원 방안 연구용역"을 추진 중이다. 2018년 1단계 용역이 완료되었으며, 2019년부터 2단계 연구용역을 추진 중이고 하굿둑 개방의 수준별로 각종 영향을 검토한 후 대책을 마련하여 기수생태계 복원 방안을 수립하는데 그 목적이 있다. 2단계 연구용역에서는 과학적이고 합리적인 기수생태계 복원방안 마련을 위해서 실제로 해수를 유입시키는 3차례의 실증실험 및 수리모형실험 등을 추진한다. 기존 연구들에서도 수문개방에 따른 해수유입 영향에 대해 모델링을 통해서 분석했지만 이는 검증이 이루어지지 않은 결과로 이번 용역에서는 실제 해수를 유입시키고 염분의 침투 및 각종 수생태 영향을 모니터링 한 후 그 결과를 반영하여 모델링을 고도화하고 있다. 최종적으로 고도화된 모델링 결과를 기반으로 기수생태계 조성 방안별로 염분, 수질, 수생태, 침퇴적 등 각종 분야에 대한 정확한 영향을 분석하고 이에 대한 대책을 포함하여 최종적으로 바람직한 기수생태계 복원 방안을 제시할 계획이다. 기수생태계 복원 방안이 계획에만 그치지 않고 실행으로 연결시키기 위해서 필요성에 대한 이해를 바탕으로 공감대를 형성해 나아가고 있으며 지역주민, 전문가, 관계기관 등 민(民)·관(官)·학(學) 다양한 의견을 수렴하여 하구지역내 수량-수질-수생태를 종합적으로 고려하여 복원 방안을 마련 후 사회적인 합의를 추진하여 확정할 예정이며, 하구의 안정적인 관리를 위해 AI 등 4차 산업혁명기술을 적극 적용하는 스마트한 하구물관리(Smart Estuary Watershed Management)"를 활용한 "하구통합물관리" (Estuary Integrated Watershed Management) 등 과학적인 관리를 추진할 계획이다.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2002.08a
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• pp.184-190
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• 2002

낙동강 하구는 서쪽으로 진해만, 동쪽으로는 부산항과 인집해 있으며 생태보호구역, 철새도래지로서 자연환경보전상 중요한 해역이다. 1987년 11월 낙동강 하구둑 건설이후 명지주거단지 매립, 신호공단 매립이 이루어졌으며 최근에는 가덕도 북쪽 해안에 부산신항만이 건설되고 있는 중이다. (중략)

• Journal of the Korean Geographical Society
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• v.40 no.4 s.109
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• pp.416-427
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• 2005

This paper aims to investigate morphological changes of deltaic barrier islands in the Nakdong Estuary and especially their spatial variations after barrage construction. We analyzed shorelines, geometrical centroids, and areas to reveal the changes of barrier islands. Here, we suggest three interesting points from this study. First, each individual barrier island in the Nakdong estuary goes through a different stage of the geomorphic cycle. The frontal barrier islands such as Sinja-do and Doyo-deung grow because they are located in front of the gates of the barrage. Sediments in water out of the gates are moved to offshore and then reworked by coastal processes such as waves and tides. Second, on the contrary, Baekhap-deung located behind Doyo-deung now diminishes indicating that sediments mainly move to the frontal growing island. Third, there is no morphological change in several barrier islands far away from the main flow of the Nakdong river such as Jinwoo-do, Daema-deung, and Jangja-do. In conclusion, barrier islands in the Nakdong estuary show distinct spatial variations. As a barrier island is closer to the main channel or is in the frontal location, there happens a very dynamic change in the morphology of the island.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4B
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• pp.405-411
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• 2008

The Nakdong River Estuary Barrage (NREB) was constructed in 1987 to prevent saltwater intrusion and to provide the sustainable water supply in the upstream channel. Sediment dredging has been conducted to eliminate deposited sediments in the approached upstream channel of the NREB. Fluvial changes and sedimentation problems have been continued due to urbanization and development in the watershed as well as construction of the NREB. However, the sufficient field monitoring and researches for sedimentation characteristics and bed changes have not been performed after construction of the NREB. Therefore, bed elevation changes and seasonal sediment concentration distribution were analyzed using the quasi-steady state model with historical field data in this study. The water surface elevation changes with and without sediment dredging operation were calculated using the developed quasi-steady state model and finally the sediment dredging effects were evaluated.

• Journal of the Korean Society of Marine Environment & Safety
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• v.14 no.2
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• pp.119-125
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• 2008

The aim of this study was to determine the characteristics of wave transformation in the shallow water of the Nakdong River estuary due to variations in air pressure, air temperature, wind speed, and wind direction. We analyzed the correlation between weather factors and wind waves in offshore regions near Geoje Island and the Nakdong River estuary in April and May 2007. The weather and wind wave data were obtained from the automatic ocean observation buoy near Geoje Island operated by the Korean Meteorological Administration (KMA). For the estuary region, the wind wave information was the result of field observations, and weather data were obtained from the Busan Meteorological Station. Field observations of water waves in April and May showed that the maximum wave height decreased by about 2.2 m. M oreover, wave height decreased significantly by about 1.3 m due to the reduction in wave energy caused by the water waves propagating from Geoje buoy to the Nakdong River estuary. We conclude that offshore or wind waves coming into the Nakdong River estuary showed considerable height variation due to the prevailing weather conditions, especially wind speed and direction. In particular, headwinds tended to decrease the wave size in inverse proportion to the wind speed.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.6
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• pp.540-552
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• 2008

We predicted to seasonal sediment transport pathway of the estuary area of the Nakdong river using the STA method. The eCSedtrend model was used to flexible application of the previous STA methods. The analysis of the seasonal interpretation of sediment transport pathway showed that the most dominant trend in the Nakdong estuary was CB+ and CB-. In case of CB+, it was identified around the area where the mud sediment was distributed and formed transport vector toward the north. Also, in case of CB-, it was identified mostly around the sand bar where the sand sediment was distributed and generally showed transport vector toward the north even though there was seasonal difference.

• 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.