• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.5
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• pp.327-334
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• 2014

This study aims to estimate settling velocity ($W_s$) for cohesive sediments from water bodies (Incheon Coast, Kulpo Stream and Han River) mainly connected to the Kyeongin Ara-waterway through the laboratory settling experiments. Results of settling tests for these sediments show that $W_s$ values for sediments are quite different each other: $W_s$ values of Kulpo Stream sediments (0.01 < $W_s$ < 3.07 mm/s) are quite similar with those of Han River sediments (0.01 < $W_s$ < 2.97 mm/s) over the whole range of suspension concentration C (0.1 < C < 90 g/ L), while they are quite different with those for Incheon Coast sediments (0.01 < $W_s$ <0.92 mm/s). Qualitative analyses on test results for physico- chemical properties of sediments and waters with respect to settling velocities show that these differences in settling velocities are mainly due to the salinity difference in the water.

• Water for future
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• v.24 no.1
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• pp.119-128
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• 1991

This study was focused on establishing the concepts of the instream flow to prevent the problems for the conceptual ambiguity and the difference in the instream flow estimation methods. The average drought flow is defined as the flow required to guarantee the minimum function of the river such as prevention of drying. The environmental control flow is defined as the flow required to control optimal river environment, the flow required for navigation, prevention of sea water-intrusion, protection of river management facilities, conservation of water Quality, fishing, prevention of river mouth closure, control of groundwater level, protection of animals and plants, and landscape. The average drought flow was obtained by flow duration analysis for the natural flows in the Han River at Indo-Bridge gaging station. When considering the 9 factors related to environment conservation, the conservation of water quality was proved to be most important. The pollutants for the river flows were estimated and the water qualities were forecasted. After comparing the water qualities in the future and water quality standards, there quired optimal dilution flow was estimated. The average drought flow and environmental control flow are all non-consumptive flows. Therefore larger flow between them, i.e., Max. (average drought flow, environmental control flow) can be the instream flow. The river management flow can be added to the flows for water utilization in the downstream. The results from this study are expected to be very helpful in the systematic river management on the other main rivers in Korea.

• Journal of Wetlands Research
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• v.16 no.2
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• pp.213-220
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• 2014

Recently, river maintenance is change due to concern for the environment increases. Thus, the river restoration and river environment is best part of river maintenance. In case of Korea, existing river is improvement straightly for flood control and transportation. When the stream channel is straightly, maintain stability is important. Thus, construction of levees along the river. The various river structures for the purpose of flood control and transportation are inhibit factors of longitudinal and lateral connectivity. Connectivity is defined as the maintenance of lateral, longitudinal, and vertical pathways for biological, hydrological, and physical processes. Long-term point of view, increased connectivity is very important for a healthy ecosystem composition. As the first step of river restoration, this study described theory and concept of river continuum and the numerical model was applied to a real topography to simulate the flow analysis with or without segregated and blocked space in the Mankyung river. The results of this study can be utilized to develop the watershed connectivity assessments methods in order to the river restoration.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.248-252
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• 2010

홍수기 호우로 인한 피해는 대부분 하천구역에서 발생되며, 이러한 피해는 인간에게 직 간접적으로 영향을 미치게 된다. 자연 상태의 하천형상은 대부분 호우로 인한 홍수로 인해 자연스럽게 만들어지게 되며, 대부분 사행하천의 형태를 띠게 된다. 사행하천에서의 흐름의 기하학적 특성은 성장이나 사멸, 또는 두 가지 모두의 형태를 보인다. 사행하천에서의 흐름 및 유속 분포는 하천제방 보호, 주운, 취수, 그리고 유사 이동 및 퇴적 패턴과 관련하여 실용적인 관점에서 연구하여야 하는 하천수리학에서는 매우 중요한 주제이다. 그리고 사행하천은 특히 만곡부가 교호적으로 나타나는 곳에서의 흐름구조가 매우 복잡하다. 이러한 사행하천에서는 회전방향이 교호적으로 바뀌는 나선형의 흐름(2차류)이 3차원적으로 발생하는 것으로 알려져 있다. 본 연구에서는 사행하천이 많은 국내 하천특성을 고려하여, 하천 만곡부에서의 흐름특성을 분석하고자 하였으며 2차원 CCHE2D 와 3차원 FLOW3D 모형을 적용하였으며 가상 하도에 대하여 수리모형 실험의 실측치와 비교하여 모형의 정확성과 안정성을 검증하였다. 그리고 남강댐 하류에 대하여 만곡부의 흐름특성(유속 분포 및 최대유속경로, 수위분포, 2차류 거동, 편수위, 전단응력 분포 등)을 분석함으로써, 하천 만곡부에서의 수리적 특성을 보다 정확하게 제시하고자 한다. 모의 분석결과 동일 하도에 대하여 유량을 변동시킬 경우, 유량이 증가할수록 만곡부에서의 수리영향이 더욱 뚜렷해짐을 알 수 있었고 2차원 모형보다 3차원모형의 결과의 정확도가 더 높은 것으로 분석되었다. 곡률반경이 1,300~1,600 정도인 실제하천에 적용한 결과, 수위의 경우 2차원 결과가 3차원 결과보다 최대 3%정도 수위가 높은 것으로 나타났으며, 또한, 상관계수가 평균 0.91의 값을 보이고 있어 2차원모형과 3차원모형의 결과가 비교적 잘 일치하는 것으로 분석되었다. 흐름 분석을 통해서 만곡부에서의 최대유속은 최정점(apex)에서 보다는 오히려 최정점 이전 하도의 내측에서 발생하였으며, 정점에서의 종단유속은 감소하지만 횡단유속은 오히려 크게 증가하는 경향을 보이고 있었다. 따라서 하천설계시 사행하천의 제방 안정성 확보를 위하여 종단유속 뿐만 아니라 횡단유속 또한 고려할 필요가 있음을 확인하였다. 또한 남강댐 하류 만곡부에서의 내측 및 외측의 수위를 분석한 결과, 제방 외측의 수위가 평균수위에 비해 최대 약 37cm정도 증가하는 것으로 분석되었다. 따라서 만곡부에 대한 하천제방설계시 좌, 우안의 여유고를 일률적으로 적용하기 보다는 만곡에 따른 흐름특성을 분석하여 설계에 적용하여야 안정성 및 경제성을 동시에 확보할 수 있을 것으로 사료된다.

• Journal of Environmental Policy
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• v.6 no.2
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• pp.47-70
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• 2007

In recent days, people's requests about water resources have been developed from managing quality and quantity of water resources to forming a river environment by restoring normal function of river. To meet these requests, it is necessary to establish the concept of environmental flows. In Korea, the environmental flows was introduced as a concept of river maintenance flows in a sense of river management. The function of river maintenance flows has been changed according to what the major issue is in that age such as navigation, water quality, and prevention of saline water intrusion. As the assesment of river maintenance flows in Korea focused mainly on the function of water usage oriented in human, it could not be defined and emphasized in a sense of ecosystem as a pure meaning of environmental flows. And while the existing river maintenance flows are included the assesment of flows, there is not a practical procedure to supply them and the efficient management in a sense of environment is not performed. The environmental flows should be further developed from the river maintenance flows and changed to a new concept focused on maintaining the health of ecosystem. In other words, the environmental flows should be defined as a necessary flows for maintaining the function of river and its original value, and be considered on the same or higher value of flows for maintenance of economic activity, recreation, and power generation.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.2
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• pp.101-108
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• 2013

Ara Canal is the first artificial canal in Korea that connects the Han River and the Yellow Sea. Due to mixture of waters with different salinity and water quality, complicated hydrodynamic and water quality distributions are expected to occur inside the canal. An integrated hydrodynamic and water quality modeling system was developed using the 3 dimensional hydrodynamic model, EFDC (Environmental Fluid Dynamics Code) and the water quality model WASP (Water Quality Analysis and Simulation Program). According to the modeling results, BOD, TN, TP and Chl-a concentrations inside the canal were lower at the West Gate side than the Han River side since influent concentrations of the West Gate side are significantly lower. Chemical stratification due to salinity difference were more evident at the West Gate side as vertical salinity difference were more pronounced in this area. On the other hand, Chl-a concentrations showed more pronounced vertical distribution at the Han River side as Chl-a concentrations were higher in this area. It was notable that Dissolved Oxygen concentrations can be lower than 2 mg/L occasionally in the middle part of the canal. While major factor affecting DO concentrations in the canal are inflows via both gates, the other important factor was found to be BOD decay in the canal due to extended hydraulic residence time. This study can be used to predict hydrodynamic conditions and water quality in the canal during the year and thus can be helpful in the development of gate operation method of the canal.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.83-83
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• 2018

"하천법" 제50조는 하천수의 사용용도를 생활 공업 농업 환경개선 발전, 그리고 주운 등 하천수 사용용도를 다양화하고 있으나, 하천수 사용료의 징수대상은 발전용수, 농업용수, 생공용수, 그 밖의 용수 등 4개 용수를 대상으로 하고 있다. 발전용수는 $100m^3/d$ 에 대하여 연액 231원, 농업용수는 $1,000m^3/d$에 대하여 연액 231원(발전용수의 1/10), 생활 및 공업, 기타용수는 댐용수대를 적용(2018년 현재 52.7원/$m^3$)하고 있다. 댐용수 요금의 산정은 '댐용수를 공급하는데 소요되는 총괄 원가를 보상하는 수준'에서 결정되며, 총괄원가는 '댐용수를 공급하는데 소요되는 적정원가에 댐용수사업에 공여하고 있는 자산에 대한 적정투자보수를 가산한 금액'으로 한다. 우리나라의 생활용수 및 공업용수는 이처럼 "한국수자원공사법" 제16조제2항에 따라 국토부장관이 승인한 댐용수 단가를 적용한다. 댐용수의 산정기준은 댐용수를 공급하는데 소요되는 총괄원가이지만, 하천수로서의 생활용수 및 공업용수가 이러한 댐용수 단가를 적용하는 이유에 대해서는 이론의 여지가 있을 수 있다. 댐용수는 1987년 최초로 전국 동일요금이 적용되었고 그 이후로도 주기적으로 요금이 인상되었으며, 발전 및 농업용수는 2008년 "하천법 시행령" 개정에 의해 사용료가 결정되었다. 농업용수와 발전용수는 각 지자체의 조례에 의해 요금을 부과하였는데 최초의 단가는 농업용수가 톤당 0.00032원, 발전용수는 톤당 0.0032원, 그리고 공업용수는 톤당 0.0076원이 부과되었다. 이후 1981년 조례의 개정에 따라 공업용수는 관경에 따라 차등적인 요금체계가 확립되었는데 대략 톤당 0.01원으로 기존에 단가에 비해 비약적으로 증가하였다. 농업용수 및 발전용수의 단가가 1984년 대비 2배 상승한 것에 비해 공업용수단가는 약 7,000배가 상승하였다. 생활용수의 경우, 기존 조례에서 따로 정하지 않았고 2008년 하천법 개정과 더불어 각 조례에 규정되었다. 즉 2008년 이전까지는 생활용수에 대해 따로 요금기준이 없었던 것으로 파악된다. 이에 비하여 농업용수 및 발전용수는 1984년 2배로 상승한 뒤 현재까지 동일한 요금을 부과하고 있다. 2008년에 개정된 "하천법 시행령" 제57조(하천수 사용료의 징수)의 농업용수 및 발전용수의 단가는 기존 조례의 단가를 그대로 "하천법"이 계승한 것으로 해당 용수의 단가가 특정한 과학적 기준으로 정해진 것으로 보기는 어렵다. 따라서 현재와 같이 용수단가별로 나타나는 커다란 차이는 각 용수의 용도 및 성격, 사회적 영향 등 용수 속성에 관한 사항과 더불어 회귀율과 취배수거리 등 다양한 요인을 적용한 산정기준을 적용하는 것이 바람직할 것이다.

• Korea Science and Art Forum
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• v.16
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• pp.157-169
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• 2014

Lake Biwa Canal was a dream project that reminds us the passion and innovation of Kyoto Citizens more than water supply. It is a modernization project combining engineering knowledge and scientific technology, which started transportation by ship through big-scale civil construction as well as supplying electricity as the first waterpower plant in Japan, and it overcame the physiographic limit through adopting unique method of waterway transportation. Lake Biwa Canal, which has tangible and intangible culture heritage value as the traditional space of Kyoto, the Old Capital of 1200 years, conceives a cultural meaning that is connected through various mutual relation as well as scientific technologic factor. Lake Biwa Canal is not only the function for supplying water to gardens and temples of Kyoto region, but it is also a cultural fruit that is formed by complex causal relationship of various contents such as geographical and environmental background, the phases of the times, local development policy, political circumstances and religions. This study is aimed at interpreting the value of Lake Biwa Canal multilaterally by the convergence of cultural and technological aspects through the view of the world which the age tried to pursue, focusing on the construction of Lake Biwa Canal which was accomplished in the process of promoting the modernization of Kyoto.

• Journal of Wetlands Research
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• v.22 no.3
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• pp.194-199
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• 2020

Unlike in the past, the world is facing water shortages due to climate change and difficulties in simultaneously managing the risks of flooding. The Four Major Rivers project was carried out with the aim of realizing a powerful nation of water by managing water resources and fostering the water industry, and the construction period was relatively short compared to the unprecedented scale. Therefore, the prediction and analysis of how the river environment changes after the Four Major Rivers Project is insufficient. Currently, part of the construction section of the Four Major Rivers Project is caused by repeated erosion and sedimentation due to the effects of sandification caused by large dredging and flood-time reservoirs, and the head erosion of the tributaries occurs. In order to solve these problems, the riverbed maintenance work was installed, but it resulted in erosion of both sides of the river and the development of new approaches and techniques to keep the river bed stable, such as erosion and excessive sedimentation, is required. The water agent plays a role of securing a certain depth of water for the main stream by concentrating the flow so much in the center and preventing levee erosion by controlling the flow direction and flow velocity. In addition, Groyne products provide various ecological environments by forming a natural form of riverbeds by inducing local erosion and deposition in addition to the protection functions of the river bank and embankment. Therefore, after reviewing the method of determining the shape of the Groyne structure currently in use by utilizing the mobile limit flow rate and marginal reflux force, a new Critical Movement Velocity(${\bar{U}}_d$) and a new resistance coefficient formula considering the mathematical factors applicable to the actual domestic stream were developed and the measures applicable to Groyne installation were proposed.

• Journal of Korea Water Resources Association
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• v.48 no.12
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• pp.1065-1075
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• 2015

In the estuary where the structure such as river-mouth weir has been installed, the flow is developed very complicatedly due to river water from upstream, tide of the sea and floodgate operation. Especially, if basin outlets more than one exists in one estuary, the boundary conditions will be significantly more complex form. Saemangeum(SMG) project area in Korea is the most typical example. There are Mankyung river and Dongjin river in upstream. The water of them inflows into SMG project area. In the downstream, river flow was drained from inland to sea over the SMG sea dike through the sluice. The connecting channel was located between Mankyung and Dongjin basins. It functions not only as transportation by ship in ordinary period but also as flood sharing by sending flood flow to each other in flood period. Therefore, in order to secure the safety against flood, it is very important to understand the flood sharing capacity for connecting channel. In this study, the flood control effect was analyzed using numerical simulation. Delft3D was used to numerical simulation and simulated period was set up with neap tide, in which the maximum flood stage occurred due to poor drainage. Actually, three connecting channels were designed in land use plan of the SMG Master Plan, but they were simplified to a single channel for conciseness of analysis in this study. According to the results of numerical analysis, the water level difference between two basins was increased and the maximum flood stage at dike sluice was also upraised depending on decrease of conveyance. And the velocity induced by same water level difference was decreased when the conveyance became smaller. In certain conveyance above, there was almost no flood control effect. Therefore, if the results of this study are considered for design of connecting channel, it will be expected to draw the optimal conveyance for minimizing dredging construction cost while maximizing the flood control effect.