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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korea Water Resources Association
Journal Basic Information
Journal DOI :
Korea Water Resources Association
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Volume & Issues
Volume 33, Issue 6 - Dec 2000
Volume 33, Issue 5 - Oct 2000
Volume 33, Issue 4 - Aug 2000
Volume 33, Issue 3 - Jun 2000
Volume 33, Issue S1 - May 2000
Volume 33, Issue 2 - Apr 2000
Volume 33, Issue 1 - Feb 2000
Selecting the target year
Riprap Scour Countermeasures around Nonuniform Bridge Piers
Yun, Tae-Hun ; Park, Gi-Du ;
Journal of Korea Water Resources Association, volume 33, issue 4, 2000, Pages 385~392
An experimental investigation was conducted to determine the effect of a nonuniform pier on the stability of riprap placed around bridge piers. A nonuniform pier is one of which the cross-sectional dimension varies over the length of the pier and comprises a cylinder of diameter bp placed on a larger diameter of foundation bf. and the stability of riprap are significantly influenced by the height of foundation z. The critical height of foundation is defined as the height of foundation which has the same critical velocity to that of uniform pier without foundation, and it was found to be zc=0.8bf. For z
Long-term Runoff Analysis Using the TOPMODEL
Jo, Hong-Je ; Kim, Jeong-Sik ; Lee, Geun-Bae ;
Journal of Korea Water Resources Association, volume 33, issue 4, 2000, Pages 393~405
Monthly runoff was estimated using TOPMODEL which simulates ground water movement as well as surface runoff in the area of catchment. SAYUN dam which is being operated by Korea Water Resources Corporation was selected for the study, and the topographic factors of the watershed were analyzed using 1/5,000 digital map and GIS software(Arc/Info). The comparison shows good agreement between observed monthly runoff and the computation results simulated by using TOPMODEL. The catchment area of SAYUN dam was modeled by using various grid sizes in order to check the sensitivity of grid size, and the grid size of 180m was found most proper among 6 different sizes. TOPMODEL was also found superior to the existing monthly runoff models such as Kajiyama, KRIHS and Tank. Because the model requires limited number of parameters and considers topographic aspects, it is reckoned to be very useful for practical use.
An Esitimation of Lognitudinal Dispersion Coefficient in Natural Stram Using Hydraulic Model
Yun, Se-Ui ; Han, Geon-Yeon ; Han, Jeong-Seok ; Kim, Jeong-Su ;
Journal of Korea Water Resources Association, volume 33, issue 4, 2000, Pages 407~417
To estimate the longitudinal dispersion coefficient at the downstream of Jungrang-River, the undistorted 1/20 scale hydraulic model was used in this study. Experiments were conducted for dry season discharge, and Rhodamine B was used as a tracer. The relationship curve between concentration and conductivity of Rhodamine B was otained by laboratory test, and the conductivity which was measured in hydraulic model was converted to concentration using this curve. The longitudinal dispersion coefficient was calculated using the relationship between the peak concentration and the time to peak concentration. The results of this study were compared with the calculated values by the empirical equations for the longitudinal dispersion coefficient and with the field data. The results of comparison show that Parker's equation underestimates, and Liu'g equation and Iwasa and Aya's one overestimate, and McQuivey and Keefer's equations, Fischer's one, Magazine's one, and Seo and Cheong's one predict relatively well. The measured data sets were relatively close to the observed ones in natural river. The longitudinal dispersion coefficient at the downstream of Jungrang-River was estimated
The Estimation of Areal Rainfall Quantiles in Han River Basin
Kim, Gyeong-Deok ; Go, Yeon-U ; Heo, Jun-Haeng ;
Journal of Korea Water Resources Association, volume 33, issue 4, 2000, Pages 419~426
It is very important to establish sufficiently long and reliable annual maximum rainfall data in estimating areal rainfall quantiles of Han River Basin. The data from 9 gauging stations measured by Korea Meteorological Administration may meet such a requirement, however the number of these data sets is too small to estimate overall areal rainfall quantiles in large basin such as Han River Basin. In order to solve such a problem, the space correlations of many sites' data measured by Korea Ministry of Construction and Transportation and Korea Water Resources Corporation (the number of sites is 59) were used for modification of rainfall measure density. And areal rainfall quantiles according to each sub-basin were estimated based on regression analysis.
Analysis of Flood Inundated Area Using Multitemporal Satellite Synthetic Aperture Radar (SAR) Imagery
Lee, Gyu-Seong ; Kim, Yang-Su ; Lee, Seon-Il ;
Journal of Korea Water Resources Association, volume 33, issue 4, 2000, Pages 427~435
It is often crucial to obtain a map of flood inundated area with more accurate and rapid manner. This study attempts to evaluate the potential of satellite synthetic aperture radar (SAR) data for mapping of flood inundated area in Imjin river basin. Multitemporal RADARSAT SAR data of three different dates were obtained at the time of flooding on August 4 and before and after the flooding. Once the data sets were geometrically corrected and preprocessed, the temporal characteristics of relative radar backscattering were analyzed. By comparing the radar backscattering of several surface features, it was clear that the flooded rice paddy showed the distinctive temporal pattern of radar response. Flooded rice paddy showed significantly lower radar signal while the normally growing rice paddy show high radar returns, which also could be easily interpreted from the color composite imagery. In addition to delineating the flooded rice fields, the multitemporal radar imagery also allow us to distinguish the afterward condition of once-flooded rice field.
A Study on Drought Trend in Han River Basin
Kim, Hyeong-Su ; Mun, Jang-Won ; Kim, Jae-Hyeong ; Kim, Jung-Hun ;
Journal of Korea Water Resources Association, volume 33, issue 4, 2000, Pages 437~446
THe drought analysis is performed by applications of truncation level method and conditional probability concept for hydrologic time series in Han river basin. The distributed trend of conditional probability is determined using kriging method for the time series. This study uses daily flowrate, monthly rainfall, and daily high temperature data sets. The daily flowrate data of 12 years(1986~1997) is used for the analysis. Also, the 14 years' data sets(1986~1999) for monthly rainfall and daily high temperature obtained from the National Weather Service of Korea are used in this study. In the cases of flowrate and rainfall data sets, the estimated value corresponding to the truncation level is decreased as the truncation level is increased but in the high temperature data, the value is increased as the truncation level is increased. The conditional probability varies according to the observations and sites. However, the distributed trend of drought is similar over the basin. As a result, the possibility of the drought is high in the middle and lower parts of Han river basin and thus it is recommended the distributed trend of drought be considered when the plan or measures for drought are established.
Development of Optimal Reservoir System Operation Model for Water Supply by Applying MIP Technique and Reappraisal of Water Supply Capability of Nakdong River Basin
Choe, Yeong-Song ; An, Gyeong-Su ; Park, Myeong-Gi ;
Journal of Korea Water Resources Association, volume 33, issue 4, 2000, Pages 447~459
Since the development of water resources is getting more difficult than ever before because of human-sociological condition, it would be necessary to develop a practically applicable technique for the management of water resources based on demand-side concept that could reduce unusable release for more effective and appropriate allocation of limited water resources. The objective of the study is to develop an optimal reservoir system operation model for water supply and energy augmentation by the combination of water budget analysis method in downstream area by MIP technique. The applicable study of the developed model was carried out and water supply capability of Nakdong river basin was re-evaluated by the developed model. The model has been found successful to guarantee appropriate water supply to the basin by means of deficit-supply management method and also turned out to be more practical tool for an optimal reservoir system operation model than other existing models.
A Numerical Analysis of Sediment-laden Flow in Open Channel with Bed-load Effect
Yun, Jun-Yong ; Gang, Seung-Gyu ; Gang, Si-Hwan ;
Journal of Korea Water Resources Association, volume 33, issue 4, 2000, Pages 461~469
An numerical analysis of sediment-laden flow is carried out, and results are compared with the experiments of Coleman(1981, 1986) that included the several cases varying sediment size and quantity in open channel flow. K-
turbulence model is selected for the fully turbulent flow field, and the concentration equation considering the fall velocity is adopted for the concentration field. The model of Einstein and Chien(1955) is applied to couple the velocity field and the concentration field. Most of researches have been carried out without considering the bed-load thickness, but it is found that the bed-load thickness cannot be ignored in case of a large amount of sediment or a large size of it. The bed-load thickness and surface roughness are considered in this study. Here,
value, which is defined by the reciprocal of turbulent Schmidt number and is related with the concentration profile, is found to be varied according to the sediment size and quantity. Even though most of researchers have insisted that
had always larger than 1.0, it may be concluded that
can have smaller value than 1.0, that is coincident with the report of recent research.
An Assessment of Areal Evaportranspiration Using Landsat TM Data
Chae, Hyo-Seok ; Song, Yeong-Su ; Park, Jae-Yeong ;
Journal of Korea Water Resources Association, volume 33, issue 4, 2000, Pages 471~482
Surface energy balance components were evaluated by Landsat TM data and GIS with meteorological data. Calibration and validation for the applicability of this methodology were made through the estimating of the large-scale evapotranspiration (ET). In addition, sensitivity and error analysis was conducted to see the effects of the surface energy balance components on ET and the accuracy of each components. Bochong-chon located on the upper part of Guem River basin was selected as the case study area. Spatial distribution map of ET were produced for five dates: Jan. 1, Apr. 3, May. 10, and Nov. 27, 1995. The study results showed tat ET was greatly varied with the aspect and theland use type on the surface. In the case of having northeast and southeast in the aspect, ET was linearly increased depending on growing net radiation. While surface temperature has a high value, NDVI(Normalized Difference Vegetation Index) has a low value in the vegetated area. Therefore, ground heat flux was increased but ET was relatively decreased. The results of sensitivity and error analysis showed that net radiation is most sensitive and effective, ranging from 12.5% to 23.6% of sensitivity. Furthermore, the surface temperature, air temperature, and wind speed have the significant effects on ET estimation using remotely sensed data.
Two Dimensional Analysis on Inundated Flow in Floodplain
Han, Geon-Yeon ; Jeong, Jae-Hak ; Lee, Eul-Rae ;
Journal of Korea Water Resources Association, volume 33, issue 4, 2000, Pages 483~493
Two dimensional finite element model, RMA, is used to simulate flood inundation phenomena from main channel to floodplain. The marsh porosity method allows finite elements to simulate gradual transition between wet and dry states. The model is applied to prismatic trapezoidal channel to test the applicability of wetting and drying. The floodwave in a river which meanders through a floodplain is also analyzed. The short-circuiting effects, in which the flow leave the meandering main channel and takes a more direct route on the floodplain, are analyzed with various sinuosity factor and roughness coefficients. Finally, the model is applied to the midstream of the Keum River. Wet/dry calculation can simulate the various discharge condition with the same finite element networks.
Analysis of Temperature Change in April at Taegu City by Applying Multiple Intervention Model
Yu, Cheol-Sang ; Lee, Jae-Su ; Baek, Gyeong-Rok ; Kim, Jung-Hun ;
Journal of Korea Water Resources Association, volume 33, issue 4, 2000, Pages 495~503
In this study the average air temperature in April at Taegu city is analyzed and forecasted by applying an intervention model of stochastic analysis. As it is unavailable to get the data of carbon dioxide emission from a city in Korea, the points of intervention have been decided from the analysis of the data observed to be the years of 1947 and 1970. As a result of the study the mean temperature of April in Taegu city is shown to increase for a long time in the future and will also remain 0.015
/year even after 70 years from now. Even though the air temperature changes in the future will vary depending on the future exhaustion of carbon dioxide, a significant increase of air temperature cannot be avoided if the emission of carbon dioxide continues at today's level.
Forecasting of Runoff Hydrograph Using Neural Network Algorithms
An, Sang-Jin ; Jeon, Gye-Won ; Kim, Gwang-Il ;
Journal of Korea Water Resources Association, volume 33, issue 4, 2000, Pages 505~515
THe purpose of this study is to forecast of runoff hydrographs according to rainfall event in a stream. The neural network theory as a hydrologic blackbox model is used to solve hydrological problems. The Back-Propagation(BP) algorithm by the Levenberg-Marquardt(LM) techniques and Radial Basis Function(RBF) network in Neural Network(NN) models are used. Runoff hydrograph is forecasted in Bocheongstream basin which is a IHP the representative basin. The possibility of a simulation for runoff hydrographs about unlearned stations is considered. The results show that NN models are performed to effective learning for rainfall-runoff process of hydrologic system which involves a complexity and nonliner relationships. The RBF networks consist of 2 learning steps. The first step is an unsupervised learning in hidden layer and the next step is a supervised learning in output layer. Therefore, the RBF networks could provide rather time saved in the learning step than the BP algorithm. The peak discharge both BP algorithm and RBF network model in the estimation of an unlearned are a is trended to observed values.