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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korea Water Resources Association
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Korea Water Resources Association
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Volume & Issues
Volume 45, Issue 12 - Dec 2012
Volume 45, Issue 11 - Nov 2012
Volume 45, Issue 10 - Oct 2012
Volume 45, Issue 9 - Sep 2012
Volume 45, Issue 8 - Aug 2012
Volume 45, Issue 7 - Jul 2012
Volume 45, Issue 6 - Jun 2012
Volume 45, Issue 5 - May 2012
Volume 45, Issue 4 - Apr 2012
Volume 45, Issue 3 - Mar 2012
Volume 45, Issue 2 - Feb 2012
Volume 45, Issue 1 - Jan 2012
Selecting the target year
Derivation of Storage Coefficient and Concentration Time for Derivation of Lateral Inflow Hydrograph
Yoo, Chul-Sang ; Kim, Ha-Young ; Park, Chang-Yeol ;
Journal of Korea Water Resources Association, volume 45, issue 3, 2012, Pages 243~252
DOI : 10.3741/JKWRA.2012.45.3.243
The objective of this study is to analyze lateral inflow hydrologically. The IUH of lateral inflow is sum of the impulse responses of total cells in basin. This IUH bases on the Muskingum channel routing method, which hydrologically re-analysed to represent it as a linear combination of the linear channel model considering only the translation and the linear reservoir model considering only the storage effect. Rectangular and triangular basins were used as imaginary basins and IUH of each basin were derived. The derived IUH have different characteristics with respect to basin's shape. The storage coefficient of lateral inflow was also derived mathematically using general definitions of concentration time and storage coefficient. As a result, the storage coefficient of lateral inflow could be calculated easily using basin's width, length and hydrological characteristics of channel.
The Application Assessment of Future Design Rainfall Estimation Method Using Scale Properties
Lee, Moon-Hwan ; Shin, Sang-Hoon ; Bae, Deg-Hyo ;
Journal of Korea Water Resources Association, volume 45, issue 3, 2012, Pages 253~262
DOI : 10.3741/JKWRA.2012.45.3.253
The objectives of this study are to suggest the method for estimation of sub-daily extreme rainfall under climate change using scale properties and to assess the application in the 6 major weather stations including Seoul site. First, the proposed method was assessed by past observations. As the results, absolute relative errors of probability rainfall quantiles estimated by frequency analysis and scale property method show approximately 10% in the all durations. And as the result of application climate scenario, absolute relative errors of rainfall quantiles between two method show approximately 20%. From the results, the scale property method on this study will be derive as the reliable results.
Estimating Quantiles of Extreme Rainfall Using a Mixed Gumbel Distribution Model
Yoon, Phil-Yong ; Kim, Tae-Woong ; Yang, Jeong-Seok ; Lee, Seung-Oh ;
Journal of Korea Water Resources Association, volume 45, issue 3, 2012, Pages 263~274
DOI : 10.3741/JKWRA.2012.45.3.263
Recently, due to various climate variabilities, extreme rainfall events have been occurring all over the world. Extreme rainfall events in Korea mainly result from the summer typhoon storms and the localized convective storms. In order to estimate appropriate quantiles for extreme rainfall, this study considered the probability behavior of daily rainfall from the typhoons and the convective storms which compose the annual maximum rainfalls (AMRs). The conventional rainfall frequency analysis estimates rainfall quantiles based on the assumption that the AMRs are extracted from an identified single population, whereas this study employed a mixed distribution function to incorporate the different statistical characteristics of two types of rainfalls into the hydrologic frequency analysis. Selecting 15 rainfall gauge stations where contain comparatively large number of measurements of daily rainfall, for various return periods, quantiles of daily rainfalls were estimated and analyzed in this study. The results indicate that the mixed Gumbel distribution locally results in significant gains and losses in quantiles. This would provide useful information in designing flood protection systems.
A Study on Optimal Time Distribution of Extreme Rainfall Using Minutely Rainfall Data: A Case Study of Seoul
Yoon, Sun-Kwon ; Kim, Jong-Suk ; Moon, Young-Il ;
Journal of Korea Water Resources Association, volume 45, issue 3, 2012, Pages 275~290
DOI : 10.3741/JKWRA.2012.45.3.275
In this study, we have developed an optimal time distribution model through extraction of peaks over threshold (POT) series. The median values for annual maximum rainfall dataset, which are obtained from the magnetic recording (MMR) and the automatic weather system(AWS) data at Seoul meteorological observatory, were used as the POT criteria. We also suggested the improved methodology for the time distribution of extreme rainfall compared to Huff method, which is widely used for time distributions of design rainfall. The Huff method did not consider changing in the shape of time distribution for each rainfall durations and rainfall criteria as total amount of rainfall for each rainfall events. This study have suggested an extracting methodology for rainfall events in each quartile based on interquartile range (IQR) matrix and selection for the mode quartile storm to determine the ranking cosidering weighting factors on minutely observation data. Finally, the optimal time distribution model in each rainfall duration was derived considering both data size and characteristics of distribution using kernel density function in extracted dimensionless unit rainfall hyetograph.
Numerical Analysis of Dam-break Waves in an L-shaped Channel with a Movable Bed
Kim, Dae-Geun ; Hwang, Gun ;
Journal of Korea Water Resources Association, volume 45, issue 3, 2012, Pages 291~300
DOI : 10.3741/JKWRA.2012.45.3.291
We conducted a three-dimensional numerical simulation by using the FLOW-3D, with RANS as the governing equation, in an effort to track the dam-break wave.immediately after a dam break.in areas surrounding where the dam break took place as well as the bed change caused by the dam-break wave. In particular, we computed the bed change in the movable bed and compared the variation in flood wave induced by the bed change with our analysis results in the fixed bed. The analysis results can be summarized as follows: First, the analysis results on the flood wave in the L-shaped channel and on the flood wave and bed change in the movable-bed channel successfully reproduce the findings of the hydraulic experiment. Second, the concentration of suspended sediment is the highest in the front of the flood wave, and the greatest bed change is observed in the direct downstream of the dam where the water flow changes tremendously. Generated in the upstream of the channel, suspended sediment results in erosion and sedimentation alternately in the downstream region. With the arrival of the flood wave, erosion initially prove predominant in the inner side of the L-shaped bend, but over time, it tends to move gradually toward the outer side of the bend. Third, the flood wave in the L-shaped channel with a movable bed propagates at a slower pace than that in the fixed bed due to the erosion and sedimentation of the bed, leading to a remarkable increase in flood water level.
Comparison of Natural Flow Estimates for the Han River Basin Using TANK and SWAT Models
Kim, Chul-Gyum ; Kim, Nam-Won ;
Journal of Korea Water Resources Association, volume 45, issue 3, 2012, Pages 301~316
DOI : 10.3741/JKWRA.2012.45.3.301
Two models, TANK and SWAT (Soil and Water Assessment Tool) were compared for simulating natural flows in the Paldang Dam upstream areas of the Han River basin in order to understand the limitations of TANK and to review the applicability and capability of SWAT. For comparison, simulation results from the previous research work were used. In the results for the calibrated watersheds (Chungju Dam and Soyanggang Dam), two models provided promising results for forecasting of daily flows with the Nash-Sutcliffe model efficiency of around 0.8. TANK simulated observations during some peak flood seasons better than SWAT, while it showed poor results during dry seasons, especially its simulations did not fall down under a certain value. It can be explained that TANK was calibrated for relatively larger flows than smaller ones. SWAT results showed a relatively good agreement with observed flows except some flood flows, and simulated inflows at the Paldang Dam considering discharges from upper dams coincided with observations with the model efficiency of around 0.9. This accounts for SWAT applicability with higher accuracy in predicting natural flows without dam operation or artificial water uses, and in assessing flow variations before and after dam development. Also, two model results were compared for other watersheds such as Pyeongchang-A, Dalcheon-B, Seomgang-B, Inbuk-A, Hangang-D, and Hongcheon-A to which calibrated TANK parameters were applied. The results were similar to the case of calibrated watersheds, that TANK simulated poor smaller flows except some flood flows and had same problem of keeping on over a certain value in dry seasons. This indicates that TANK application may have fatal uncertainties in estimating low flows used as an important index in water resources planning and management. Therefore, in order to reflect actually complex and complicated physical characteristics of Korean watersheds, and to manage efficiently water resources according to the land use and water use changes with urbanization or climate change in the future, it is necessary to utilize a physically based watershed model like SWAT rather than an existing conceptual lumped model like TANK.
An Assessment of Fish Habitat of Natural Fishway by Hydraulic Model Experiments and Numerical Analysis
Lee, Sung-Hyun ; Oh, Kuk-Ryul ; Cheong, Tae-Sung ; Jeong, Sang-Man ;
Journal of Korea Water Resources Association, volume 45, issue 3, 2012, Pages 317~329
DOI : 10.3741/JKWRA.2012.45.3.317
It is increasing to make an efforts on preventing natural river environment and preserving natural river ecosystem as development is unavoidable. In the case of inconsistent river flow caused by reservoir development, fishway is an alternative to secure fish diversity and preserve existing river ecosystem but existing fishway was established without full study for their functions. In this study, hydraulic characteristics of natural fishway established on Beakje weir's right side were analyzed. The results show that the fishway has reasonable depth and velocity condition which inhabit condition is enough for a dominant species. For assessing the optimal design of fishway, the Weighted Usable Area (WUA) was calculated by using two dimensional numerical model under the ordinary flow condition. The comparison results for various pool widths in the fishway show that the designed width has maximum WUA for adult Zacco platypus but WUA is maximized with 1m wider pool width than designed width for spawning.
Analysis of Flow and BOD Transport at the Downstream of Nam River Dam Using 2-D and 3-D Semi-coupled Models
Kim, Ji-Hoon ; Song, Chang-Geun ; Kim, Young-Do ; Seo, Il-Won ;
Journal of Korea Water Resources Association, volume 45, issue 3, 2012, Pages 331~347
DOI : 10.3741/JKWRA.2012.45.3.331
The downstream of the Nam River Dam is crucial region for long-term water resource planning for Busan and Gyeongnam Province. Thus, the analysis of flow behavior and water quality is necessary for the sustainable surface water management and the control of pollutant source. In this study, the flow field and BOD transport at the downstream of Nam River Dam were analyzed by incorporating 2-D water quality model, RAM4 and 3-D water quality model, WASP with the hydrodynamic model, RAM2 and EFDC, respectively. The application of 2-D flow analysis model, RAM2 showed that velocity distributions at the five transverse sections of the meandering part closely followed the measured values by ADCP, and the flow field and overflow characteristic at the submerged weir showed satisfactory performance compared with the result of 3-D EFDC model. In addition, the BOD concentration field obtained by RAM2-RAM4 coupled modeling was in good agreement with the result by EFDC-WASP model throughout the computational domain. The hydrodynamic characteristic and water quality at the downstream reach of Nam River Dam are mainly influenced by the Dam discharge, and the water quantity is closely related to the water quality control and fishery environment at the lower part of Nakdong River. Therefore, when further quantitative analysis is necessary regarding these issues, 2-D semi-coupled modeling is recommended in terms of computational effectiveness and model application aspect.