• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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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.

• Journal of Korean Society on Water Environment
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• v.27 no.5
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• pp.710-718
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• 2011

An integrated water quality management of reservoir and river would be required when the quality of downstream river water is affected by the discharge of upstream dam. In particular, for the control of downstream turbidity during flood events, the integrated modeling of reservoir and river is effective approach. This work was aimed to develop a laterally-averaged two-dimensional hydrodynamic and water quality model (CE-QUAL-W2), by which water quality can be predicted in the downstream of Yongdam dam in conjunction with the reservoir model, and to validate the model under two different hydrological conditions; wet year (2005) and drought year (2010). The model results clearly showed that the simulated data regarding water elevation and suspended solid (SS) concentration are well corresponded with the measured data. In addition, the variation of SS concentration as a function of time was effectively simulated along the river stations with the developed model. Consequently, the developed model can be effectively applied for the integrated water quality management of Yongdam dam and downstream river.

• Journal of environmental and Sanitary engineering
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• v.23 no.3
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• pp.47-57
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• 2008

This study was predicted the diffusion of the conservative contaminant using a two-dimensional hydraulic model. The research area is upper basin of Jakwang river where the possibility where the pollutant of vast quantity will flow is high. Using SMS model, we calculated two-dimensional stream flow. And using this result, predicted the conduct of the conservative contaminant by pollutant transfer diffusion calculation. And also we predicted flow and contaminant diffusion in the near estuary by constructed guide bank. As a result of study, pollutant effect scope of the conservative contaminant was predicted with the fact that will broaden because of interception by guide bank. As discharge was increased from the Jakwang river, The diffusion of the pollutant is accelerated, also the effect scope increases.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.629-633
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• 2008

Frequently occurring flood and drought have increased the necessity of an effective water resources control and management of river flows. Therefore, the simulation of the flow distribution in natural rivers is very important to the solution of a wide variety of practical flow problems in water resources engineering. Usually in many flow problems, two-dimensional approach can provide good estimates of complex flow features in the flow around islands and obstructions, flow at confluence and flow in braided channel. The objective of this study is to examine validation of developed an accurate and robust two-dimensional finite element method with wet and dry simulation in complex natural rivers. Milyang river, and Kumho river and Keum river were performed for tests. The results were compared with those of existing model. The suggested model displayed reasonable flow distribution compared with existing model in dry area for application of natural river flow. As a result of this study, the developed general two-dimensional model provide a reliable results for flow distribution of wet and dry domain, it could be further developed to basis for extending to water quality and sediment transport analysis.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.425-429
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• 2006

The understanding and prediction of the behavior of flow in open channels are important to the solution of a wide variety of practical flow problems in water resources engineering. Recently, frequent drought has increased the necessity of an effective water resources control and management of river flows for reserving instream flow. The objective of this study is to develop an efficient and accurate finite element model based on Streamline Upwind/Petrov-Galerkin(SU/PG) scheme for analyzing and predicting two dimensional flow features in complex natural rivers. Several tests were performed in developed all elements(4-Node, 6-Node, 8-Node elements) for the purpose of validation and verification of the developed model. The U-shaped channel of flow and natural river of flow were performed for tests. The results were compared with these of laboratory experiments and RMA-2 model. Such results showed that solutions of high order elements were better accurate and improved than those of linear elements. Also, the suggested model displayed reasonable velocity distribution compare to RMA-2 model in meandering domain for application of natural river flow. Accordingly, the developed finite element model is feasible and produces reliable results for simulation of two dimensional natural river flow. Also, One contribution of this study is to present that results can lead to significant gain in analyzing the accurate flow behavior associated with hydraulic structure such as weir and water intake station and flow of chute and pool.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.908-911
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• 2004

The purpose of this study is to investigate the applicability of the two dimensional model in natural rivers. In this study, two dimensional unite element model, SMS, is used to simulate a complex flow along with the sediment movements in the natural river. The RMA-2 model embeded in SMS is used to simulate flow phenomena and SED-2D model is employed to simulate sediment transport. The model is applied to the confluence zone of the Gam River and mouth of Nakdong River. For model calibration, the result of the unsteady flow analysis is compared with the Typhoon 'Rusa' data. In addition, the runoff analysis was conducted for the determination of the project flood and the flood forecasting. The simulation results presented the characteristics of two dimensional flow with velocity vector and flow depth. The sediment transport characteristics are shown in terms of sediment concentration as well as bed elevation change. Accordingly, the SMS model in this study turned out to be very effective tool for the simulation of the hydrodynamic characteristics under the various flow conditions and corresponding sediment transports in natural rivers.

• Journal of Industrial Technology
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• v.26 no.A
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• pp.129-137
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• 2006

In this research, we made a one and two-dimensional analysis of numerical data collected from the bend curvature of a bended river section. According to the result from the numerical analysis, the inflow ＆ output angle caused a water level deviation which increased with an increase of the flood discharge. From the water level deviation of our two-dimensional numerical model, we obtained the maximum slope of 6,67% when the inflow and output angle was 105 degrees and the flood discharge was 500 CMS. As for the right side, the differences with the one-dimensional numerical model were reduced when the angle was more than $90^{\circ}$. As for the left side the differences were reduced when the angle was more than $105^{\circ}$. For a river with more than 90 degrees bend curvature, a hydraulic experiment would be more appropriate than a numerical analysis.

• Water for future
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• v.26 no.3
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• pp.87-101
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• 1993

A finite element model RIV-FEM2 for the hydrodynamic study in a river is developed based on two-dimensional shallow water wave equation and dissipative Galerkin's method. RIV-FEM2 consists of pre-processing, analysis processing and post-processing. Pre- and analysis processing is programmed with Fortran-77 and post-processing with turbo-Pascal respectively. The model is tested with two dimensional problems, including flow through bends, bridges, and symmetric contraction. The two dimensional tests shows stable and efficient results for various situations. Applicability of the model is verified by applying to natural river. The model will provide a basic contribution to the hydrodynamic analysis in a river.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1331-1334
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• 2004

Wet/Dry phenomena typically incorporate a number of complex flow mechanism. These include a momentum transfer and turbulent mixing caused by the delivery of water. However currently available one dimensional schemes applicable to wet/dry process cannot effectively simulate such process. Two dimensional finite element model, SU/PG, is used to simulate complex flow in this study. The Wetted Area Method in SU/PG allows elements to transition gradually between wet and dry states. The model is applicable to a straight river reach with irregular bathymetry. Wet/dry calculation using the wetted area method can simulate simple numerical test. The computed results of velocity vectors and water depth agree with those of observed. The methodology Presented in this study will contributed to two-dimensional wet/dry analysis in a river in this country.

• Ecology and Resilient Infrastructure
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• v.3 no.4
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• pp.307-314
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• 2016

River restoration has recently been performed not only for the improvement of the artificial parts in the past but also for the restoration of abandoned river reaches which were blocked and isolated. For the restoration of abandoned river reaches, it is important to recover the hydraulic and ecological connectivity in the isolated space by longitudinal structures like levees. But because the assessment tools to determine whether the river restoration is performed properly are so rare at present, we aim to provide a tool for assessing ecological connectivity in a target river in this study. In the first step, one-dimensional numerical model for rainfall-runoff and channel routing was developed and then applied to the watershed of the Cheongmi Stream. In this step, a numerical model was developed to assess the restoration of connectivity. The model consists of two parts: one part is to convert the results of one-dimensional channel routing into two-dimensional spatial distribution. The other is to calculate the habitat suitability index according to time steps by using two-dimensional hydraulic features. The model was applied to a restoration area of the Cheongmi Stream. The advantage of this study is that two-dimensional hydraulic analysis can be easily obtained from one-dimensional hydraulic analysis without a complex and time-consuming two-dimensional analysis. HHS (Hydraulic Habitat Suitablility) by sections of target reaches and target species can be easily obtained using the results of this study.