• 한국수자원학회논문집
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• 제57권6호
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• pp.385-392
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• 2024

하천으로 해수의 유입을 막기 위해 하구에 수문을 설치함으로써 해수유입은 막을 수 있었으나 이로 인해 하천의 유속은 급격히 감소하여 흐름이 없는 하천으로 변화되었다. 하천은 흐름이 있어야 하천의 기능을 유지할 수 있기에 본 연구에서는 하구에 수문 설치로 인하여 흐름이 발생하지 않은 하천인 심곡천을 대상으로 수문 운영을 통해 하천의 흐름을 개선하도록 검토하였다. 조위에 따라 수문을 운영하게 되면 최고 및 최저 목표수위를 유지하면서 현재 0.05 m/s의 느린 유속에서 약 10배 정도 빠른 0.49 m/s까지 상승시켜 물이 흐르는 하천으로 변화시킬 수 있는 것으로 검토되었다.

• 한국물환경학회지
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• 제27권6호
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• pp.905-913
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• 2011

This study was conducted to characterize the discharge feature of pollutant load from the upper and lower watershed influencing on the water quality of South Han River using the empirical equation and Factor Analysis. The results of regression analysis between flow rate and pollutant load were as follows. In the streams of the upper watershed of South Han river, $BOD_5$ and $COD_{Mn}$ were increased as the flow rate was increased. Also, steep increases in SS and TP were observed with positive correlation with the flow rate while change in TN was slightly shown. On the other hand, in the streams of the lower watershed of South Han river, $BOD_5$ was negatively correlated with the flow rate, being decreased with the increase in the flow rate. However, changes in $COD_{Mn}$, TN, SS, and TP showed a similar trend with those observed in the upper watershed. With Factor Analysis of the water quality and various components, it was appeared that the flow rate, SS, and TP were significantly correlated each other and they were indicated as the principal component influencing on water quality in the streams of the upper watershed. In contrast, $BOD_5$, $COD_{Mn}$ and TOC were significantly correlated each other and they were included as the principal pollution component of the streams in the lower watershed. From these results, it was conclusive that the upper watershed of South Han River was mainly affected by non point source pollutants while the lower watershed was influenced by point source pollutants from the developed areas.

• Journal of Ecology and Environment
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• 제32권4호
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• pp.221-227
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• 2009

This study describes time lag responses between hydrological variables and phytoplankton biomass in a regulated river system, the lower Nakdong River in South Korea. The lower Nakdong is a typical flow-controlled lotic system, and its limnological characteristics are influenced by climatic variation such as monsoons and summer typhoons. Mean rainfall in the area during summer is about 1,200 mm, which comprises >60% of annual rainfall. Our results show that the regulation of flow in the Nakdong by multi-purpose dams from 1995 to 2004 affected phytoplankton dynamics. Diatom blooms occurred in winter, when the limited discharge allowed for proliferation of the phytoplankton community. Using multiple regression analysis, we detected significant time-delayed relationships between hydrological variables and phytoplankton biomass. These results may be useful for water resource managers, and suggest that 'smart flow' control would improve water quality in large regulated river systems of the Republic of Korea.

• 한국수자원학회논문집
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• 제54권3호
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• pp.191-201
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• 2021

국내의 하천은 급격한 도시화와 산업화로 인해 자연하천의 모습은 사라지고 이수와 치수 기능 위주의 하천관리가 이루어져왔다. 최근 하천이 갖는 자연적 특성을 회복하는 환경적 측면을 강조한 생태하천 복원 사업에 대한 관심이 높아지고 있으나, 하천복원의 시작은 생태계에 필요한 환경유량의 적절한 평가가 우선되어야 한다. 본 연구는 낙동강 제1지류 하천인 감천을 대상으로 부항댐 건설에 따른 유황변화 및 환경유량의 변화를 추정하여 하천생태계 서식처에 미치는 영향을 분석하였다. 감천의 환경유량을 평가하기 위한 분석대상은 감천에 서식하는 어류인 피라미, 긴몰개와 하천주변 식생을 선택하였으며, 미육군공병단에서 개발된 HEC-EFM (Ecosystem Function Model)을 활용하여 환경유량을 산정하였다. 평가된 환경유량은 GIS 분석과 연계 하였으며, 수생계의 하도내 서식처를 공간적으로 도시하여 댐 건설 전후 수생생물의 서식처 면적비교 및 서식처 연결성 분석을 수행하였다. 본 연구결과를 바탕으로 하천생태계의 서식처 개선을 위한 환경유량 산정 및 서식처 연결성 분석을 통하여 하천 복원 및 하천환경을 고려한 댐 운영의 기초자료로 활용할 수 있을 것으로 판단된다.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.14-19
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• 2005

Instream flow is necessary to manage the basic function of the rivers. The evaluation method of instream flow in a big river has been studied widely, However, the study in a small river hasn't researched. In theses days the environmental function of a river becomes very important. The evaluation method and secure of instream flow are basic conditions to perform it. Especially view of stream, recreation, protection of ecology are highly demanded in a urban according to the multipurpose of river spaces. Methods for determining the instream flow in the stream were explored and examined through careful reviews and evaluations of available literatures. Development of the instream flow estimation method is based on the reviewed results and methods which can be used within the acceptable levels.

• 한국물환경학회지
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• 제33권6호
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• pp.640-649
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• 2017

The purpose of this study is the analysis of the water quality spatial characteristics for the main stream of Nakdong River in consideration of the tributary inflow. The flow and water quality (BOD, TOC, TP) data for 32 monitoring stations located in the main stream and the tributaries of Nakdong River were collected from 2003 to 2016. From the results of the flow and water quality analyses for each site, a status map of the flow and the water quality for Nakdong River was produced. The water quality of each river section was classified according to seven river-environment standards. The water quality changes in the main stream before and after the confluence were analyzed spatially. As a result, the water quality of Kumho River, in particular the Kumho B to Kumho C section, is the worst among the tributaries. In addition, the water quality grades of the lower streams such as Nam River and Miryang are worse than that of the upper streams of the Nakdong River. In the case of the main stream, the water quality grades of the sections between the Wicheon and Nam River confluences and the section from Nakbon L to Nakbon N are relatively poor.

• 한국환경복원기술학회지
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• 제13권2호
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• pp.95-104
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• 2010

The purpose of this study is to analyze the correlation between physical stream characteristics and bed materials in natural rivers. Accordingly, four natural rivers were selected reference streams, they were Nam river, Sumjin River, Naesung River and Han River. Grain size distributions of bed materials were gravels, cobbles and boulders in Han river and Nam river, were sand, gravels, cobbles and boulders in Sumjin river and were sand in Naesung river. Four reference streams were divided into each two reference reaches (straight and bend) by plan and profile characteristics of naturally meandering stream. Therefore various reference reaches were chosen in the aspect of physical stream characteristics and grain size distributions. The results investigated and analyzed are as follows. The streams that grain sizes distributions of river bed materials were coarse were stable because they had variety of bed slope without sediment deposition, and then the riffles frequency and the physical characteristics were various. Also, velocitydepth regime were various in four kinds, and the response parts for water level change were small, so that channel flow status were stable and excellent condition. On the other hand, sand river that grain sizes distributions of river bed materials were fine had not the variety of parameters as velocity-depth regimes, sediment deposition, channel flow status and riffles frequency, so that the physical stream characteristics were not various.

• 한국물환경학회지
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• 제22권6호
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• pp.1144-1150
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• 2006

Recently, as water pollution accidents in rivers have increased, there is an increased interest in water quality forecast with accurate simulation. QUAL2E model, widely used for water quality analysis, uses the same hydraulic characteristics, such as depth and velocity, in a reach. The flow of the river is changed by various hydraulic constructions or by topography in a real river channel. In this study, a hydraulic connection module is developed to consider flow variations of river channels in QUAL2E model. The module uses the simulations results of non-uniform flow of a 1-D hydraulic model such as DWOPER or HEC-RAS. The improved QUAL2E model with this module was applied to a downstream section of Paldang Dam on the Han River. The results show the variation of water quality very well in a reach where flowing vary abruptly, like the Jamsil submerged weir.

• 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.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2009년도 학술발표회 초록집
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• pp.810-814
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• 2009

Two dimensional steady and unsteady numerical models are applied to bend reaches of the Lower Han River and the superelevation at the Ichon-Banpo bend area of Han River was observed. The flow characteristics in the meandering river are complicated due to the effects of the centrifugal force. The centrifugal force makes the outside water surface level increase and the outside velocity decrease. To study this complex flow studying two dimensional flow is important and useful to design flood control countermeasures, the analysis of sedimentation and the site selection of intake structures. Especially, the superelevation between inside and outside of the bend should be considered to determine the height of embankment. In this study, the water surface elevations in both bank sides of the bend were measured in two reaches during floods in 2007 and 2008. And then the two-dimensional simulation using RMA-2 model was carried out. The upstream and downstream boundary conditions on bend reaches were determined by FLDWAV which is one-dimensional unsteady model. Finally, the observed data are compared with simulation results and the results of the several superelevation formulas, and the flow characteristics of the bend are discussed.