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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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Journal DOI :
Korea Water Resources Association
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Volume & Issues
Volume 38, Issue 12 - Dec 2005
Volume 38, Issue 11 - Nov 2005
Volume 38, Issue 10 - Oct 2005
Volume 38, Issue 9 - Sep 2005
Volume 38, Issue 8 - Aug 2005
Volume 38, Issue 7 - Jul 2005
Volume 38, Issue 6 - Jun 2005
Volume 38, Issue 5 - May 2005
Volume 38, Issue 4 - Apr 2005
Volume 38, Issue 3 - Mar 2005
Volume 38, Issue 2 - Feb 2005
Volume 38, Issue 1 - Jan 2005
Selecting the target year
The derivation of GIUH by means of the lag time of Nash model
Kim, Joo-Cheol ; Yoon, Yeo-Jin ; Kim, Jae-Han ;
Journal of Korea Water Resources Association, volume 38, issue 10, 2005, Pages 801~810
DOI : 10.3741/JKWRA.2005.38.10.801
The lag time is one of the most important factors for estimating a flood runoff from streams. It is well known to be under the influence of the morphometric properties of basins which could be expressed by catchment shape descriptors. In this paper, the notion of the geometric characteristics of an equivalent ellipse proposed by Moussa(2003) is applied for calculating the lag time of geomorphological instantaneous unit hydrograph(GIUH) at the basin outlet. The lag time is obtained from the observed data of rainfall and runoff by using the method of moments suggested by Nash(1957), and the procedure based on geomorphology is used for GIUH. The relationships between the basin morphometric properties and the hydrological response are discussed as applied to 3 catchments In Korea. Additionally, the shapes of equivalent ellipse are examined how then are transformed from upstream area to downstream one. As a result, the relationship between the hydrological response and descriptors is shown to be comparatively good, and the shape of ellipse is presented to approach a circle along the river downwards. These results may be expanded to the estimation of hydrological response of ungauged catchment.
Velocity and Discharge Measurement using ADCP
Lee, Chan-Joo ; Kim, Won ; Kim, Chi-Young ; Kim, Dong-Gu ;
Journal of Korea Water Resources Association, volume 38, issue 10, 2005, Pages 811~824
DOI : 10.3741/JKWRA.2005.38.10.811
The ADCP is an instrument based on Doppler effect, which measures discharge of a river in a short time while crossing it. In this study we aim to make a comparison of the discharge results from a moving-vessel ADCP with those measured by velocity-area method at the same cross-section, and to investigate the characteristics of velocity and discharge data using ADCP. Bathymetry measured by ADCP almost coincides with that by direct depth measurements. Because velocity data from ADCP are essentially instantaneous, individual velocity profiles obtained by ADCP are rather different from time-averaged velocity profiles. But spatially averaged velocity profiles of the individual ADCP data near the comparable verticals have similar vertical velocity pattern with the time-averaged ones. The average velocity profile from repeatedly crossed data is also similar with the time-averaged one. In case of the velocity distribution, individual and spatially averaged data for the sub-width of mid-section method Have good agreement with those by velocity-area method. Discharge data determined by averaging several ADCP measurement transects have
of difference with those from velocity-area method, and as the number of measurement increases, the relative difference to the velocity-area method decreases.
Evaluation of Typhoon Hazard Factors using the EST Approach
Lee, Soon-Cheol ; Kim, Jin-Kyoo ; Oh, Kyoung-Doo ; Jun, Byong-Ho ; Hong, Il-Pyo ;
Journal of Korea Water Resources Association, volume 38, issue 10, 2005, Pages 825~839
DOI : 10.3741/JKWRA.2005.38.10.825
Application of the EST approach for the simulation of the risk-based typhoon hazard potential is described in this paper. For six selected cities In the Korean peninsula, EST simulations for one hundred years were performed one hundred times using historical typhoon data as a training data set. The analytical results of EST simulations were then post-processed to estimate the means, standard deviations, and ranges of variation for the maximum wind velocities and the daily rainfalls. From the comparison of the averages of the wind velocities for the 100 year recurrence interval typhoons, the wind hazard potential of them was revealed to be highest for Mokpo among the six cities, followed by Busan, Cheju, Inchun, Taegu, and Seoul in descending order For the flood hazard potential associated with a typhoon, Busan was ranked to be the highest hazard potential area, followed by Mokpo, Cheju, Seoul, Inckun, and Taegu. In terms of the overall typhoon hazard potential, cities in the southern coastal regions were identified as being exposed to the most severe typhoon hazard.
Development of a PTV Algorithm for Measuring Sediment-Laden Flows
Yu, Kwon-Kyu ; Muste, Marian ; Ettema, Robert ; Yoon, Byung-Man ;
Journal of Korea Water Resources Association, volume 38, issue 10, 2005, Pages 841~849
DOI : 10.3741/JKWRA.2005.38.10.841
Two-phase flows, e.g. sediment-laden flow and bubbly flow, have two different flow profiles; flow velocity and sediment velocity. To measure velocity distributions of two-phase flows, it is necessary to use sophisticated instruments which can separate velocity profiles of two-phases. For bubbly flows, PIV (Particle Image Velocimetry) or PTV (Particle Tracking Velocimetry) has given fairly good velocity profiles of two-phases. However, for sediment-laden flows, the applications of PIV or PTV has not been so successful, because the sediment particles introduced to the flow kept the images from being analyzed. A new algorithm, which consists of several image analysis methods, is proposed to analyze sediment-laden flows. For detection algorithm, threshold method, edge detection method, and thinning method are adapted, and for finding matching pair PIV and PTV routines are combined. The proposed method can (1) detect sediment particles with irregular boundaries, (2) remove reflected images and scattered images, and (3) discriminate tracer particles from reflected images of sediment particles.
Development of Fast and Exact FFT Algorithm for Cross-Correlation PIV
Yu, Kwon-Kyu ; Kim, Dong-Su ; Yoon, Byung-Man ;
Journal of Korea Water Resources Association, volume 38, issue 10, 2005, Pages 851~859
DOI : 10.3741/JKWRA.2005.38.10.851
Normalized cross-correlation (correlation coefficient) is a useful measure for pattern matching in PIV (Particle Image Velocimetry) analysis. Because it does not have a corresponding simple expression in frequency domain, several fast but inexact measures have been used. Among them, three measures of correlation for PIV analysis and the normalized cross-correlation were evaluated with a sample calculation. The test revealed that all other proposed correlation measures sometimes show inaccurate results, except the normalized cross-correlation. However, correlation coefficient method has a weakpoint that it requires so long time for calculation. To overcome this shortcoming, a fast and exact method for calculating normalized cross-correlation is suggested. It adopts Fast Fourier Transform (FFT) for calculation of covariance and the successive-summing method for the denominator of correlation coefficient. The new algorithm showed that it is really fast and exact in calculating correlation coefficient.
Automatic Calibration of Rainfall-runoff Model Using Multi-objective Function
Lee, Kil-Seong ; Kim, Sang-Ug ; Hong, Il-Pyo ;
Journal of Korea Water Resources Association, volume 38, issue 10, 2005, Pages 861~869
DOI : 10.3741/JKWRA.2005.38.10.861
A rainfall-runoff model should be calibrated so that the model simulates the hydrological behavior of the basin as accurately as possible. In this study, to calibrate the five parameters of the SSARR model, a multi-objective function and the genetic algorithm were used. The solution of the multi-objective function will not, in general, be a single unique set of parameters but will consist of the so-called Pareto solution according to various trade-offs between the different objectives. The calibration strategy using multi-objective function could decrease calibrating time and effort. From the Pareto solution, a single solution could be selected to simulate a specific flow condition.
Anisotropy of Turbulence in Vegetated Open-Channel Flows
Kang, Hyeong-Sik ; Choi, Sung-Uk ;
Journal of Korea Water Resources Association, volume 38, issue 10, 2005, Pages 871~883
DOI : 10.3741/JKWRA.2005.38.10.871
This paper investigates the impacts of turbulent anisotropy on the mean flow and turbulence structures in vegetated open-channel flows. The Reynolds stress model, which is an anisotropic turbulence model, is used for the turbulence closure. Plain open-channel flows and vegetated flows with emergent and submerged plants are simulated. Computed profiles of the mean velocity and turbulence structures are compared with measured data available in the literature. Comparisons are also made with the predictions by the k-
model and by the algebraic stress model. For plain open-channel flows and open-channel flows with emergent vegetation, the mean velocity and Reynolds stress profiles by isotropic and anisotropic turbulence models were hardly distinguished and they agreed well with measured data. This means that the mean flow and Reynolds stress is hardly affected by anisotropy of turbulence. However, anisotropy of turbulence due to the damping effect near the bottom and free surface is successfully simulated only by the Reynolds stress model. In open-channel flows with submerged vegetation, anisotropy of turbulence is strengthenednear the vegetation height. The Reynolds stress model predicts the mean velocity and turbulence intensity better than the algebraic stress model or the k-
model. However, above the vegetation height, the k-
model overestimates the mean velocity and underestimates turbulence intensity Sediment transport capacity of vegetated open-channel flows is also investigated by using the computed profiles. It is shown that the isotropic turbulence model underestimates seriously suspended load.
A Study of the Urbanization Effect on the Precipitation Pattern in Urban Areas
Oh, Tae-Suk ; Ahn, Jae-Hyun ; Moon, Young-Il ; Kim, Jong-Suk ;
Journal of Korea Water Resources Association, volume 38, issue 10, 2005, Pages 885~894
DOI : 10.3741/JKWRA.2005.38.10.885
Since the 1970s, rapid Industrialization has brought urbanization nationwide. In this paper, thirty one years data(1973-2003) ate used to evaluate variability of major cities. Before assessing the context between urbanization and variability of rainfall, the rural areas are selected to compare with urban ones. Thus, average, trends, variations, and nonparametric frequency analysis methods were employed for evaluating variation of annual precipitation, seasonal precipitation, 1 hour annual maximum design rainfall and 24 hour annual maximum design rainfall for both urban and rural areas. The result have shown that summer precipitation relatively increased In urban areas compared to that in rural areas.
Development of Semi-Distributed TOPMODEL
Bae, Deg-Hyo ; Kim, Jin-Hoon ;
Journal of Korea Water Resources Association, volume 38, issue 10, 2005, Pages 895~906
DOI : 10.3741/JKWRA.2005.38.10.895
The diversity of observed hydrologic data and the development of geographic information system leads significant progress for developing distributed runoff models in the world. One of the typical examples is TOPMODEL, but the spatial coverage of its application Is limited on small headwater basins. The purpose of this study attempts to overcome its limitation and consequently develops a semi-distributed TOPMODEL. The developed model is composed of two components: a watershed runoff component for a lumped representation of hydrologic runoff process on the catchment scale and a kinematic wave type hydraulic channel routing component lot routing the catchment outflows. The application basin is the
upper Soyang dam site and several daily and hourly events are selected for model calibrations and verifications. The model parameters are estimated on 1990 daily event. The model performance on correlation coefficient between observed and computed flows are above 0.90 for the verification events. It is concluded that the developed model in this study can be used for flood analysis in large drainage basins.