• Journal of the Korean Geographical Society
• /
• v.33 no.3
• /
• pp.355-364
• /
• 1998

Flume experiments are conducted to describe the channel morphology at a tributary junction and to examine the influence of channel arrangements and hydrologic conditions on the channel morphology. When flow momenta of two tributaries are equal, a receiving stream tends to align with an axis bisecting junction angle. It causes lateral migration of a receiving stream according to an initial channel arrangement. As a result, the post-fonfluent channel morphology varies with plan geometry of a confluence such as symmetry, transition and asymmetry. Bed scour is the most notable morphology within a junction site. Its shape is characterized by steep walls which are primarily influenced by junction angle. Key control of scour dimension is also junction angle. Although the principle of accordant junction has been undoubtedly accepted, discordance is commonly developed at model and natural stream confluences. Unit discharge ratio of confluent streams is the most crucial factor because both discharge and sediment concentration ratios have an effect on discordance at a junction.

• Journal of the Korean Society of Industry Convergence
• /
• v.10 no.4
• /
• pp.275-283
• /
• 2007

This study aims at the calculation of a variation of flow characteristics of main channel for tributary inflow in river junction. So this study was analyzed the variation of flow depth and velocity in main channel for a change of inflow degree. For this purpose, FLDWAV model are carried out for variations of $30^{\circ}$, $60^{\circ}$ and $90^{\circ}$ tributary inflow at junction. Results show that velocity ratio(V1/V3) increases and flow depth ratio(H1/H3) decreases for discharge ratio(Q1/Q3) of upstream and downstream when degree increases in junction. And FLDWAV model was applied at a real river junctions. Selected area is a junction of Gumho river and Sin stream. Results show that pattern is similar to a virtual channel.

• Journal of Animal Science and Technology
• /
• v.53 no.6
• /
• pp.549-561
• /
• 2011

Livestock wastewater is being discharged without treatment from Hasen's pig farm cluster in WangGoong (WG) area into the Iksan Stream, eventually flowing into the ManGyung (MG) at the upstream junction. Although it is well known that before discharge, wastewater must satisfy the pig slurry discharge standards; because of ongoing remodeling, proper treatment is not being performed. According to public records, wastewater from the WG pig farm cluster is responsible for 3.6% of MG River pollution and 2.0% of the SaeManGuem (SMG) Reservoir pollution. As a result, upstream water treatment quality has become primary concern for development of the SMG project. All physicochemical constituents and pathogenic microbes, such as chemical oxygen demand ($COD_{Cr}$), biochemical oxygen demand ($BOD_5$), total suspended solids (TSS), total nitrogen (TN), total phosphorous (TP), fecal coliforms, Escherichia coli and Salmonella at the effluent of WG Plant (S-1) exceed the effluent standards. This is mainly due to insufficient wastewater treatment: the WG Plant is under renovation to increase water purification efficiency. By comparing the water quality at the S-7 junction, where the the Iksan Stream (pig farms) and the Wanggoong Stream (no pig farms) merge, it is clear that farming facilities and improper treatment can critically affect surrounding water quality. While it is clear throughout this study that the level of all physicochemical parameters and pathogenic microbes along the Stream decreased due to sedimentation, biodegradation and/or dilution. An alarming problem was discovered: the existence of pathogenic microbe count(E coli, Salmonella) in the lagoon wastewater and the stream water. Not only were high concentrations of these pathogens themselves found, but the potential existence of more serious pathogens could rise to more dangerous conditions.

• Journal of environmental and Sanitary engineering
• /
• v.10 no.3
• /
• pp.56-66
• /
• 1995

To investigate environmental impacts of inland fish- farms on the water quality of a stream, environmental parameters including physical, chemical and biological factorswere estimated at trount- farm in 1994. Influences( F-1) were polluted as passing through fish tank( F-2) and settle pond( F-3), so organic and inorganic nutrient concentrations became very high in effluents( F-4). BOD$_{5}$, Chl. a, Nitrite and heterotrophic bacterial numbers in the junction site(5-2) of F-4 and S-1( upstream) were highest among the stream sites. BOD$_{5}$ was proved to a good parameter of organic pollution, and nitrite of Inorganic nutrients in the fishery and it's affected stream, The high concentration of BOD$_{5}$ and Chl. a in S-2 were decreased in downstream(5-3, 5-4). It seems that this results are due to dilution or sedimentation effect. This supposition requires further testing about the sediment of stream. The results of this paper demonstrate that fish farming can deteriorate water quality of a stream by changing environmental factors.

• Journal of Environmental Science International
• /
• v.17 no.7
• /
• pp.783-793
• /
• 2008

The purpose of this study is to analyze the sensitivity of the RMA2 model parameters reflecting the flow characteristics of stream junction and thus understand the hydraulic characteristics of the channel confluence flow. This study dealt with the input parameters of the RMA-2 model, a two-dimensional numerical analysis model widely used for researches both at home and abroad. The parameters of the RMA-2 model are roughness coefficient, turbulent diffusion coefficient, Coriolis forces latitude, Density, and mesh size. This study those parameters estimated from actual heavy rainfall, and varied the parameter size by (-)30%${\sim}$+30% to review the characteristics of the flow characteristics of the channel section. Weobserved that when the ratio of the channel width was relatively small, the smaller the approaching angle was, the farther from the junctions became the generating place of the maximum flow velocity, however, when the ratio of the channel width was relatively large, the larger the approaching angle was, the farther the generating place of the maximum flow velocity from the junctions became. In particular, the distance between junctions and the place where the maximum flow velocity generated showed an absolute correlationover 90% of the relative channel width, but an inverse relationwas found when the distance to the place where the flow velocity generated was shortened as relative the channel width between the main channel and tributary increased.

• 한국방재학회:학술대회논문집
• /
• 2007.02a
• /
• pp.603-607
• /
• 2007

Recently, the frequency of unexpecting heavy rains has been increased due to abnormal climate and extreme rainfall. There was a limit to analyze one dimension or two dimension stream flow of domestic rivers that was applied simple momentum equation and fixed energy conservation. Therefore, hydrodynamics flow analysis in rivers has been needed three dimensional numerical analysis for correct stream flow interpolation. In this study, CFD model on FLOW-3D was applied to stream flow analysis, which solves three dimension RANS(Reynolds Averaged Navier-Stokes Equation) control equation to find out physical behavior and the effect of hydraulic structures. Numerical simulation accomplished those results was compared by using turbulence models such as $k-{\backepsilon}$, RNG $k-{\backepsilon}$ and LES. Those numerical analysis results have been illustrated to bends and junctions by the turbulence energy effects, velocity of flow distributions, water level pressure distributions and eddy flows.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.12
• /
• pp.3360-3371
• /
• 1995

Hydrodynamic characteristics of a stratified flow at a Y-junction were examined analytically. Gas is supplied through the main horizontal channel and liquid is introduced into the gas stream from the Y-shaped bottom branch. Analysis was performed with irrational flow and inviscid fluid assumptions. The Stokes' inverse transformation technique was adopted to convert the real x-y plane into the x-.psi. plane. The potential flow equation was solved numerically in the transformed (x-.psi.) plane and the interface profile, pressure distribution and the streamlines were obtained. The effects of the inlet conditions, injection angle and the gravity on the flow characteristics were also examined. To check the validity of the present method, the previous resultant the two-dimensional obtuse wedge flow was compared. The inverse transformation technique turned out to be also very useful to predict the hydrodynamic characteristics of a stratified flow with the pressure variation at a Y-shaped mixing junction.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2006.05a
• /
• pp.1328-1332
• /
• 2006

As the city is developed, Sewerage outlet is installed for the discharge of rainfall special at new town or modified the existed sewerage network. But the sewerage outlet is influenced to the cannel flow. In this paper, for analyzing variation of flow properties by installing sewerage outlet, it was experimented a with $120^{\circ}$ channel junction. The water depth is rapidly increasing at the just before sewerage installed position, but the velocity is represented increasing at the just after sewerage installed position. In addition, the biggest increment of water depth and velocity is represented $3.0m^3/hr{\sim}4.0.m^3/hr$. At the position of the sewerage outlet installation, separate install at up and downstream is rather than only one position at up or down stream. If it was not install both installation, the upstream installation is better than downstream installation.

• Journal of Korean Society on Water Environment
• /
• v.34 no.3
• /
• pp.285-292
• /
• 2018

This study was performed in order to identify the red tide-causing organism and to understand the characteristics of the water quality during the winter of 2015 and 2016 in the Oncheon stream, a tidal river in Busan, where red tide often occurs in the wintertime. Two sites were selected on the stream and the surface water was sampled a total of 28 times during the experimental period. Twelve water quality characteristics, including water temperature, pH, DO, COD, total-N (T-N), total-P (T-P), and salinity were analyzed in order to test water quality. The cell numbers of cryptomonads were counted directly by microscopic observation. The nucleotide sequences of the partial 28S rRNA gene and psbA gene from metagenomic DNA, derived from each sampling site, were analyzed. According to the results, the alga most responsible for the bloom was identified as Teleaulax OC1 sp., which belongs to the cryptomonads. Three items of chl-a, pH, and DO were positively correlated with the cell numbers of the cryptomonads counted at the upper stream of the tidal area (St 1) while eight items of chl-a, TOC, BOD, total-N, COD, SS, pH, and DO were positively correlated with the cells located at the junction between the stream and Su-young river (St 2) in the order.

• Journal of the Korean association of regional geographers
• /
• v.10 no.3
• /
• pp.568-578
• /
• 2004

This study is aimed at investigating floodgate characteristics and environmental issues in Gwangjucheon and examining possible problems of expanding river maintenance water being carried on in the context of river recovery works. In general, the obtained results show the following. The treatment water provisioned in the restoration project of the drying stream going through the water circulation device can pollute the land and groundwater in the Gwangjucheon Basin. Besides, although about $17,565m^3$/day of water is available in the upper ground, most of it go to the junction and exhausting directly to the waste water treatment or going into the groundwater. Because of the drying stream, the amount of water going to the ground is increased. Therefore, efficient land use along with regulations to protect cultivated land and ensure recovery works of city stream through the recovery of water circulation by constructing and expanding a special drainage system are of vital importance.