• 자원환경지질
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• 제56권4호
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• pp.435-445
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• 2023

삼각주는 하천이 운반하던 퇴적물이 호수나 바다, 하천의 본류와 같은 상대적으로 저 에너지의 환경을 만나 쌓인 퇴적 지형이다. 그 중 하천의 합류 지역에 생긴 삼각주는 하천 기하와 수리학적 특성에 큰 영향을 줄 수 있기 때문에 하천 관리 및 연구에서 중요하게 다루어진다. 최근 낙동강 내 대규모 준설과 보 건설로 하천 합류 지역의 평형상태가 깨지고 있다. 하지만 하천의 자연 회복성으로 인한 지속적인 퇴적으로, 인위적인 준설 이전의 자연상태로 되돌아가고 있다. 시계열 관측 결과 합류 지역의 삼각주는 준설 이후 지속적으로 성장하다가, 일정 크기에 도달하면 전반적인 크기의 변화없이 소규모의 성장과 후퇴를 반복하는 동적 평형상태에 이른다. 본 연구에서는 합류 지역 삼각주가 지류의 유사량과 본류의 유량에 따라 체결된 동적 평형 상태에 도달한다는 가정을 바탕으로 합류 지역의 퇴적-침식 작용을 설명하는 모델을 개발하였다. 모델은 지류 공급 퇴적물의 퇴적과 본류로 인한 침식 작용, 두 가지 기작을 토대로 한다. 모델에 사용된 낙동강을 대표하는 침식 계수는 낙동강 내 주된 합류 지역을 이용하여 추정했다. 개발된 모델을 이용하여 지류 유사량과 본류 유량에 따른 합류 지역 삼각주 평형 위치의 민감도 분석을 수행했고, 이후 주된 합류 지역의 연평균 유량, 유사량 데이터를 활용하여 낙동강 합류부 삼각주들의 동적 평형 위치를 예측하였다. 마지막으로 감천-낙동강에 기록된 일별 유량과 유사량 데이터를 활용하여 감천-낙동강 삼각주의 발달에 대한 모의 실험을 진행하였다. 모델을 통해 각 합류부 삼각주의 형성 여부를 예측하였고, 감천-낙동강 삼각주의 거동의 경향 또한 잘 예측하였지만, 단순화 과정에서 발생한 오차와 한계로 인해 감천-낙동강 삼각주에서 실제 발생하는 후퇴를 정확히 예측하지는 못하였다. 본 연구 결과는 합류 지역을 통한 낙동강 본류의 유사 공급량에 대한 기초 정보를 제공하여 하천 정비 및 유지에 기초 모델로 사용할 수 있다.

• 한국지반신소재학회논문집
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• 제9권2호
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• pp.1-9
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• 2010

연약지반 개량을 위한 수평배수공법으로 샌드매트 공법이 활발하게 사용이 되고 있다. 그러나 현재 압밀침하를 촉진시키는 재료로써 샌드매트에 관련하여 문제점들이 발생하고 있다. 무엇보다도, 샌드매트공법에 요구되는 모래의 양이 증가함에 따라 공급이 원활하게 이루어지고 있지 않은 상태이다. 또한, 수많은 건설현장에서 모래 및 골재의 무분별한 채취로 인하여 생태환경의 파괴 및 천연적인 자연경관의 손상을 초래하고 있다. 따라서 본 연구에서는 이러한 문제점을 해결하고자 샌드매트 대체제로서 풍쇄 슬래그의 사용이 적합한지를 판단하기 위하여 기본 물성시험, 실내 통수능 시험, 침하특성 분석과 현장모형을 실험을 통한 통수능과 침하특성, 프로그램을 통한 침하특성을 통해서 확인하고자 한다.

• 한국환경과학회지
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• 제29권6호
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• pp.659-672
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• 2020

Water and sediment qualities were investigated in the Oncheon Stream and at the Wondong bridge of the Suyoung River, during the summer rainy season, 2019. Dissolved oxygen (DO) showed the lowest levels at 4.7 and 5.0 m/L, and biogeochemical oxygen demand (BOD) showed the highest at 5.3 mg/L downstream where the tributary flows into the main river. Chemical oxygen demand (COD) increased from 2.0 to 5.9 mg/L on average as it flowed downstream, The COD/BOD ratio decreased gradually as it flowed downstream, reaching 1.0. However, COD/BOD ratio at the Wondong bridge was 5.8-22.2, indicating that easily biodegradable and non-biodegradable organic matter flows into the Oncheon Stream and Suyoung River, respectively. Total nitrogen (T-N) / total phosphorus (T-P) ratio tended to decrease from 72 to 21 as it flowed downstream, measuring 71 to 86 at the Wondong bridge. The water quality index (WQI) generally improved better than grade IV after heavy rainfalls. However, DO and T-P were the parameters that deteriorated the WQI. Ignition loss (IL), COD, T-N, and T-P of sediments had distribution of 1.44 ± 1.01%, 0.35 ± 0.16%, 43 ± 63 mg/kg, and 10.9 ± 21.9 mg/kg, respectively. These were several times lower than the annual averages of IL, T-N, and T-P in 2017 before the dredging project was conducted in the first half of 2018.

• 생태와환경
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• 제38권3호통권113호
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• pp.334-340
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• 2005

The chemical forms of Cd, Cu, Pb, and Zn were analysed by sequential extraction technique to evaluate the effects of drying and heating of dredged sediments from Lake Chungcho. The most abundant fraction of Cd, Cu, and Zn in the wet and untreated sediment was organic/sulfidic fraction that is state in reducing environment such as the bottom condition of Lake Chungcho, while Pb dominated in residual fraction. This means that the source of Cd, Cu, and Zn in the Chungcho lake sediment is related to the organic degradation and Pb to the erosion from surrounding rocks. With drying and oxidation by dredging, heating treatment, and disposal of the lake sediment, the chemical forms of studied metals changed greatly from organic/sulfidic fraction to adsorbed and reducible fractions which are more labile in oxygenated environment. Organic/sulfidic fraction of Cd, Cu and Pb in the wet sediment was transformed with drying and heating treatments to the labile ones like adsorbed and reducible fraction, but Zn to carbonate and reducible fraction. Heating of the sediment at $320^{\circ}C$ greatly increased the labile fraction of Cd and Cu, while that at $105^{\circ}C$ for Pb and Zn. It is believed that the increase in labile forms of heavy metals in the sediments by drying and heating is caused by the contact with oxygen during drying and heating and by the increase of pH of the pore water at the expense of organic/sulfidic fraction. It is concluded that the drying and oxidation currently used in the treatment of dredged sediment can increase labile forms of heavy metals in the sediment, and the potential of the metal availability from the sediment.

• 한국산학기술학회논문지
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• 제15권2호
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• pp.1149-1156
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• 2014

본 홍수피해를 저감하기 위해 하천의 제방 증축, 하도준설, 수리구조물의 설치 등에 있어 적합한 설계가 요구된다. 이 중에서 배수문에 관한 하천설계기준을 살펴보면 설치위치는 7개의 항목으로 나열되어 있으나, 그 기준이 상세하지 않음을 알 수 있다. 제내지의 토지이용 및 유역특성을 반영한 배수문의 적절한 위치를 산정하기 위하여 외수위를 고려한 내수침수모의가 수행되어 정량적 평가가 이뤄져야 한다. 그러나 내수침수모의는 대개 수리 수문학적 특성을 동시에 고려해야 되기 때문에 매우 복잡하고 시간이 오래 소요된다. 따라서, 본 연구에서는 배수문 설치에 대한 정량적 검토를 바탕으로 간편하고 정확한 설계방법을 제시하였다.

• 한국해양공학회지
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• 제22권2호
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• pp.28-33
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• 2008

From the 1997 to January, 2004, a groin 156m long was constructed at the mouth of the Heoya river-mouth as a protection and barrier. To understand the changes to Jinha beach from the blockade of the river mouth, several aerial photographs, etc., were compared, which showed that the changes were significant. Comparing these results to the state of the area before construction of the groin, the blockade of the river was relaxed, but the formation of the tombolo, in the middle groin area was accelerated and the total Jinha beach erosion and especially the erosion of the southern part of Jinha beach was developed. But according to statements by residents and some current documents, the blockade of the Heoya-river mouth is still underway at the surrounding areas of the groin and chronic dredged sand has been used for littoral nourishment at the northern part of the middle groin and on Jinha beach. The result of numerical simulation based on the present state shows that if this sort of dredging is stopped, the sand accumulation will progress near the river mouth groin and the existing tombolo at the middle groin will progress to the north and severe erosion will occur at the southern coastline near the middle groin and the farthest southern part of Jinha beach, and Jinha beach itself will experience a gradual erosion. The main reason for these erosions should be the typhoons that are happening during the summer season. To provide protection from these kinds of undesirable erosions, a total of 23 numerical simulations have been done. It has been shown that submerged breakwaters at the front area of the beach will be efficient to protect from main beach erosion, but there should be alternative proposals for the influence of the river mouth blockade.

• 한국항해항만학회지
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• 제40권5호
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• pp.257-263
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• 2016

Mombasa is the principle port of Kenya, serving inland countries in Eastern and central Africa. Mombasa port has undergone a massive infrastructure upgrade and dredging works with an expectation that more vessels and large post Panamax ships will be able to enter Mombasa port. Therefore, it is vital to carry out a marine traffic risk assessment in order to quantify the degree of navigation safety needed in the Mombasa approach channel and also to evaluate the navigation risk imposed on transit traffic by local ferry traffic. In this paper, a marine traffic risk assessment is carried out using the IWRAP mk2, Environmental Stress (ES) model, and the PARK model. Risk assessment results show that Likoni area has an unacceptable stress/risk ranking at 20.7% by the ES model and 38.89% by the PARK model. The IWRAP mk2 model shows that the crossing area has the highest risk of crossing collision and the area at the entrance to the inner channel has a high risk of grounding. The conclusions derived from this study will provide the basis for proposing the most effective countermeasure to improve navigation safety in the Mombasa approach channel.

• Ocean Science Journal
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• 제41권4호
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• pp.211-219
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• 2006

A comparison was made of population of the economically important cockle Anadara (=Scapharca) broughtoni (Bivalvia, Arcidae) inhabiting different areas of the Razdolnaya River estuary at the head of Amurskii Bay (Peter the Great Gulf, East Sea). Also, changes in cockle population density and structure, as well as in cockle growth rates during the last 20 years were studied. In all years of investigation, the morphometrical parameters and growth rates of cockles were smaller at the sites located close to the River mouth than farther down-estuary. The differences can be attributed to higher concentration of suspended particulate matter, decreased salinity and water temperature, as well as a longer exposure to these unfavorable environmental factors at sites located close to the River mouth, compared to farther sites. For two decades, cockle population density had decreased by almost 30 times at some sites in the River estuary. The main reason for this population decline is commercial over-fishing of the cockle. Besides, for the last 20 years, linear parameters of the cockles in the population decreased approximately by 30% and weight parameters, almost two times. Cockle growth rates also decreased for this period. Evidently, these facts are due to the damaging effect of dredging.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2016년도 춘계학술대회
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• pp.81-84
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• 2016

Mombasa is the principle port of Kenya, serving hinter countries in Eastern and central Africa. Mombasa port has undergone a massive infrastructure upgrade and dredging works with an expectation that more vessels and large post Panamax ships will be able to call at Mombasa port. Therefore, it is vital to carry out a marine traffic risk assessment so as to quantify the degree of navigation safety on Mombasa approach channel and also to evaluate navigation risk imposed on transit traffic by local ferry traffic. In this paper marine traffic risk assessment is carried out using IWRAP mk2, Environmental Stress model, and PARK model. Risk assessment results show that Likoni area has unacceptable stress/ risk ranking at 20.7% on ES model and 38.89% by PARK model. IWRAP mk2 model shows that crossing area has the highest risk of crossing collision and the area at the entrance to inner channel has a high risk of grounding. The conclusions derived from this study will provide the basis for proposing the most effective countermeasure so as to improve navigation safety in Mombasa approach channel.

• 수산해양교육연구
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• 제27권1호
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• pp.253-261
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• 2015

The chemical water quality and fish assemblage of Dong Stream to assessment of environmental improvement after discharge seawater were investigated from July to December 2013. BOD and DO were significantly different between before and after discharge seawater, while pH and SS did not significant. A total of 11 fish species, 218 individuals and 10,525.1g were collected. Dominant fish species were Mugil cephalus, Konosirus punctatus, Acanthogobius flavimanus and Leiognathus nuchalis which account for 77.5% of total individuals collected, and they were estuarian species. Peak number of species and individuals, and biomass occurred in September, whereas diversity index were highest in November. The water ecosystem of Dong Stream have been changed estuarian environment. As a result of stream assessment on water quality and ecosystem, water quality have been improved as 'III' grade. These results suggested that stream restoration policies such as drain pipes maintenance, management of pollution sources and riverbed dredging to improve environment and recover habitate of Dong Stream were need for set up and establishment of regular monitoring system.