• 한국환경과학회지
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• 제3권1호
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• pp.11-16
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• 1994

Generally, it is difficult to predict water quality in a tidal river, because tidal flows make the transport phenomena more complicated. The purpose of this study is to clarify long-term mass transport in a tidal river through suggestion of simulation model. A simulation model based on a Lagrangian coordinate system, which has the advantage reducing numerical dispersion, was used to calculate changes in concentration of chlorides. Several field surveys were conducted to verify calculated results. Concludingly, long-term behavior of mas transport in a tidal river can be represented using the model.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.173-173
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• 2015

The flood water level in tidal river is determined by the joint effects of flood discharge and tidal water levels at downstream boundary. Due to the variable tidal boundary conditions, the evaluated design water levels associated with a certain flood event can be significantly different. To avoid determining of design water levels just by a certain tidal boundary condition and remove the influence of variability in boundary condition from the evaluation of design water levels, a probabilistic approach is considered in this study. This study focuses on the development of a method to evaluate the realistic design water levels in tidal river with taking into account the combined effects of river discharge and tidal level. The flood water levels are described by the joint probability of two driving forces, river discharge and tidal water levels. The developed method is applied to determine design water levels for the tidal reach of the Han River. An unsteady flow model is used to simulate the flow in the reach. To determine design water levels associated with a certain flood event, first, possible boundary conditions are obtained by sampling starting times of tidal level time series; then for each tidal boundary condition, corresponding peak water levels along the channel are computed; and finally, design water levels are determined by computing the expectations of the peak water levels. Two types of tides which are composed by different constituents are assumed (one is composed by $M_2$, and the other one is composed by $M_2$ and $M_2$) at downstream boundary, and two flood events with different maximum flood discharges are considered in this study. It is found that (a) the computed design water levels with two assumed tides have no significant difference for a certain flood event, though variability of peak water levels due to the tidal effect is considerably different; (b) tidal effect can reach to the Jamsil submerged weir and the effect is obvious in the downstream reach of the Singok submerged weir; (c) in the tidally affected reach, the variability of peak water levels due to the tidal effect is greater if the maximum flood discharge is smaller.

• 한국수자원학회논문집
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• 제54권6호
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• pp.433-442
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• 2021

하구역으로부터 감조하천 상류로 전파되는 조석파의 특성을 고찰하기 위하여 먼저 국내 연안에서 천문조인 M2분조와 천해조인 M4분조에 대한 조화상수를 분석해 조석비대칭 현상을 파악하였다. 하구역에서 천해조가 크게 발달함에 따라 한강과 금강의 경우 창조우세, 영산강의 경우 낙조우세가 형성된다. 이러한 조석비대칭 현상은 조류속 자료를 분석함으로써 재확인할 수 있다. 조류속 분석 결과 왕복성 조류패턴을 보이는 금강하구와 영산강하구의 경우와는 달리 한강하구의 경우 강화도 주변의 복잡한 지형 및 수로에 기인하여 회전성 조류패턴이 나타나기도 한다. 그러나 잔차류를 제거할 경우 조류속 관측자료 역시 조위와 일관된 창낙조우세를 보이고 있다. 하구역에서 형성된 조석비대칭 현상은 조석파가 감조하천 상류로 전파되면서 천해조의 성장과 더불어 더욱 심화되는 경향이 있다. 하천의 마찰특성과 단면형상에 따라 조석파의 전파양상에도 차이가 발생하여 수심이 얕은 한강과 금강의 경우 SD하구로 분류되어 에너지 소산이 매우 큰 반면 수심이 깊은 영산강의 경우 WD하구로 분류되어 에너지 소산이 덜 한 것으로 나타나고 있다.

• 한국안전학회지
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• 제29권6호
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• pp.104-110
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• 2014

The Han River is the only waterway in Korea where estuary is not blocked by dykes so that tidal water is flowing in and out through the tidal reach. The extreme tidal range in the Yellow Sea causes an intense flood current, stretching over horizontal extents of tens of kilometers into the rivers. To elucidate the flow reversal by discharge conditions and transient tidal level in the Han river, numerical simulations were conducted under 7 boundary conditions for two days with 10 minute time step. As the flow conditions changed from low discharge and high tidal difference to high discharge and low tidal difference, the flow reversals became weaker and the velocity of forward flow direction became higher due to the increased flow momentums and decreased tidal differences. In the case of normal flow, the maximum reverse velocity was 0.4 m/s, which was equivalent to the maximum forward velocity. In addition, the pattern of the development and decay of forward and reverse flow was presented.

• 물과 미래
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• 제25권2호
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• pp.67-78
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• 1992

Several field surveys were conducted to investigate changes of water quality with time in a tidal river. Results indicated that nitrification process were dependent on the change of salinity and suspended solids concenttration. Therefore laboratory batch experiments were conducted, using suspended solids and sediment taken from a tidal river, to study the effect of salinity on nitrification and to estimate kinetic parameters of it in the tidal river. suspended solids and sediment were sampled at a point in the middle stream. Sediments were collect from the aerobic layer of mud. The change of nitrogen concentration with time was clearly explained with Monod groth model and kinetic parameters were obtained by curve fitting method. Changes in NH4-N, NO2-N, and NO3-N concentrations in the river ROKKAU with time were simulated well using Lagrangian reference frame and parameter values obtained in the laboratory tests. T도 mechanism of nitrification by suspended solids and sediment in a tidal river is shown to depend on tidal effects.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.199-202
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• 2008

It is well-known fact that tidal difference between the ebb and flow in Yellow Sea is about 9 m so that it has largest value in the world. This wide range of tide level enables Yellow Sea water to intrude into main stream of Han River. However, the study of the tidal reach of Han River has not been carried out thoroughly since North and South Koreas share this region so that topography data and physical measurement are lacking. In this study, to examine the reverse flow and dispersion behavior by tidal effect at the tidal reach of Han River, 2-D river analysis models were applied. RMA-2 was applied to calculate the horizontal velocities and water surface elevation. With the results of velocities and water depth, RAM4, which is 2-D advection-dispersion model based on FEM was simulated to analyze the horizontal transport behavior of BOD.

• 물과 미래
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• 제18권1호
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• pp.67-73
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• 1985

금강 감조구간의 조석전파현상을 장파, 중력파공식의 수치적분에 의한 통상적인 방법을 이용하여 조사하였다. 이용된 역학방정식은 비선형항을 포함하여 천해조를 산정할 수 있도록 하였다. 수립된 모델은 평균대, 중, 소조시의 감조구간의 조석전파를 산정하는데 이용되었으며 또한 상류홍수유출과 하구조석의 상호작용에 의한 감조구간의 수립분포를 산정하는데도 초기적용되었다. 이 연구의 목적은 하구의 체절공사가 시작되기 전의 금강감조구간의 조석역학을 조사하는데 있다.

• 한국해양환경ㆍ에너지학회지
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• 제4권1호
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• pp.14-23
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• 2001

영일만의 해수순환에 영향을 미치는 조석잔차류와 형산강 하천수의 거동 특성을 규명하기 위하여 2차원 수치모형실험을 수행하였다. 수치모형실험의 결과는 기존의 관측자료들과 잘 일치하였으며, 영일만의 북쪽 달만갑 연안으로부터 포항신항을 거쳐 장기갑 연안을 따라 외해로 빠져나가는 조석잔차류 거동을 잘 재현하였다. 영일만의 잔차류에 대한 조류의 영향은 미약하며 파랑이나 바람에 의한 영향이 크지만 영일만의 전형적인 조석잔차류의 거동에 미치는 형산강 하천수의 역할은 지배적인 것으로 나타났다.

• 한국안전학회지
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• 제33권2호
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• pp.132-137
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• 2018

Compared with general rivers, fluctuations of the water level and the river bed are severe in the tidal river. In hydro-dynamic aspect, such fluctuation gives different river-bed data to us according to observing period. The time-dependent river-bed data and pre-estimation of the Manning's roughness coefficient which is the key factor of numerical modelling induces uncertainty of evaluating the design flood level. Thus it is necessary to pay more attention to calculate the flood level at tidal rivers than at general rivers. In this study, downstream of the Imjin River where is affected by tide of the West Sea selected as a study site. From the numerical modelling, it was shown that the unsteady simulation gave considerable mitigation of the water level from the starting point to 15 km upstream compared to the steady simulation. Either making a detention pond or optional dredging was not effective to mitigate the flood level at Gugok - Majung region where is located in the downstream of the Imjin River. Therefore, a more sophisticated approach is required to evaluate the design flood level estimation before constructive measures adopted in general rivers when establishing the flood control plan in a tidal river.

• 한국해양학회지
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• 제14권2호
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• pp.71-77
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• 1979

낙동강은 유역이 약 2.4 $10^{4}$$\textrm{km}^2$ 이고 길이가 525km에 달하는 대하천으로 농업, 공업, 생활용수 등 영남지방의 용수 공급원으로서 중요하다. 최근에는 하구역 에서 천해어장, 홍수대책, 하도개수, 간척, 매립 등 다양한 이용개발이 계획 또는 실시 되고 있다. 따라서 이 하구역의 효육적 이용과 관리를 위하여는 하구수의 유동을 지배하는 요인인 하천조석에 관한 기초적인 연구가 불가결하다.