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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 30, Issue 6 - Dec 1997
Volume 30, Issue 5 - Oct 1997
Volume 30, Issue 4 - Aug 1997
Volume 30, Issue 3 - Jun 1997
Volume 30, Issue 2 - Apr 1997
Volume 30, Issue 1 - Jan 1997
Selecting the target year
Estimation of Curve Number by DAWAST Model
Kim, Tae-Cheol ; Park, Seung-Gi ; Mun, Jong-Pil ;
Journal of Korea Water Resources Association, volume 30, issue 5, 1997, Pages 423~430
It is one of the most important factors to determine the effective rainfall for estimation of flood hydrograph in design schedule. SCS curve number (CN) method has been frequently used to estimate the effective rainfall of synthesized design flood hydrograph for hydraulic structures. But, it should be cautious to apply SCS-CN originally developed in U.S.A to watersheds in Korea, because characteristics of watersheds in Korea and cropping patterns especially like a paddy land cultivation are quite different from those in USA. New CN method has been introduced. Maximum storage capacity which was herein defined as Umax can be calibrated from the streamflow data and converted to new CN-I of direst condition of soil moisture in the given watershed. Effective rainfall for design flood hydrograph can be estimated by the curve number developed in the watersheds in Korea.
Decision Suport System for Real-Time Reservoir Operation during Flood Period
Sim, Sun-Bo ; Kim, Seon-Gu ;
Journal of Korea Water Resources Association, volume 30, issue 5, 1997, Pages 431~439
This paper describes the development of a decision support system (DSS) for the real time reservoir operation that aims to maximize the flood control effect. In the decision support system, model base and real time data processing subsystem are included along with the graphical user interface(GUI) that is able to visualize the forecasted runoff hydrographs at the flood control points and reservoir water levels resulting from the model run as well as the current hydrologic status. The system was verified through the pseudo real time applications to the Taechong reservoir operation with the historical flood events of the Kum river basin occurred in July, 1987 and August, 1995, Decision making processes were performed using the developed system and the results were compared with the real operations at that time. The reservoir operation using the pseudo real time application of DSS were simulated by the flood runoff simulation model, that shows the reservoir operation by DSS were successful in flood control for the lower Kum River.
Application of Multi-Dimensional Precipitation Models to the Sampling Error Problem
Yu, Cheol-Sang ;
Journal of Korea Water Resources Association, volume 30, issue 5, 1997, Pages 441~447
Rainfall observation using rain gage network or satellites includes the sampling error depending on the observation methods or plans. For example, the sampling using rain gages is continuous in time but discontinuous in space, which is nothing but the source of the sampling error. The sampling using satellites is the reverse case that continuous in space and discontinuous in time. The sampling error may be quantified by use of the temporal-spatial characteristics of rainfall and the sampling design. One of recent works on this problem was done by North and Nakamoto (1989), who derived a formulation for estimating the sampling error based on the temporal-spatial rainfall spectrum and the design scheme. The formula enables us to design an optimal rain gage network or a satellite operation plan providing the statistical characteristics of rainfall. In this paper the formula is reviewed and applied for the sampling error problems using several multi-dimensional precipitation models. The results show the limitation of the formulation, which cannot distinguish the model difference in case the model parameters can reproduce similar second order statistics of rainfall. The limitation can be improved by developing a new way to consider the higher order statistics, and eventually the probability density function (PDF) of rainfall.
Development of Stochastic Real-Time Forecast System by Storage Function Method
Bae, Deok-Hyo ;
Journal of Korea Water Resources Association, volume 30, issue 5, 1997, Pages 449~457
This study attempts to develop a stochastic-dynamic real-time flow forecasting model for an event-orient watershed storage function model (SFM), which has been used as an official flood computation model in Korea, and to evaluate its performance for real-time flow forecast. The study area is the 747.5
Hwecheon basin with outlet at Gaejin and the 8 single flow events during 1983-1986 are selected for comparison and verification of model parameter and model performance. The used model parameters in this study are the same values on field work. It is shown that results from the existing model highly depend on the events, but those from the developed model are stable and well predict the flows for the selected flood events. The coefficient of model efficiency between observed and predicted flows for the events was above 0.90. It is concluded that the developed model that can consider model and observation uncertainties during a flood event is feasible and produces reliable real-time flow forecasts on the area.
NAPL Removal from Contaminated Soil Using Steam Injection
Lee, Sang-Il ; Jang, Yeon-Su ; Kim, Seon-Gi ;
Journal of Korea Water Resources Association, volume 30, issue 5, 1997, Pages 459~465
The possibility of NAPL removal from contaminated soil was studied using the steam injection technique. Both single (octane, toluene and xylene) and composite NAPL (gasoline) were used as contaminant. Soils used in this study were Chumunjin fine sand and weathered granitic soil, both of which are commonly found in Korea. Experimental results showed that with 1 pore volume steam injection, the NAPL removal rate was in the range of 66∼78% for sand and 45∼73% for weathered granitic soil. The steam injection technique seems to have high potential for soil remediation with advantages of relatively short operating time and no side-effect. Rise in the background temperature led to the delay of steam condensation and the increase of NAPL mobility, which resulted in the improvement of removal efficiency. In addition, water flooding after steam injection turned out to be a very efficient way of removing NAPL residual in the soil pores.
Analysis of Velocity Structure of Round Wall Jet
Kim, Dae-Geun ; Seo, Il-Won ;
Journal of Korea Water Resources Association, volume 30, issue 5, 1997, Pages 467~475
In this study, breakwater model which has several outlet pipes to discharge heated water is settled in the experimental open channel and velocity distribution of wall jet is measured. Numerical simulation of velocity structure of wall jet using 3-dimensional computer model. Fluent model, is also carried out. The calculated results are verified with the experimental results and the flow characteristics of wall jet are investigated. The length of zone of flow establishment of wall jet is shorter than that of free jet, and the diminution rate of jet centerline longitudinal velocity is larger than that of free jet. Characteristics of buoyant jet and non-buoyant simple jet simulated by Fluent model are compared. Near the outlet pipe, in the region where x/lQ is over 15, this is reversed. Comparison of vertical distribution of longitudinal velocity shows that positive velocity of non-buoyant jet is bigger than that of buoyant jet in the bottom layer and in the upper layer, negative velocity of non-buoyant jet is bigger too. Flow separation in free surface of the buoyant jet occurs in smaller distances from the outlet than the non-buoyant jet. Buoyant jet expands faster than the non-buoyant jet in vertical direction.
Estimation of Scour Depth at Bridnges and Comparative Analysis between Estimated and Measured Scour Depths
Yun, Yong-Nam ; Lee, Jae-Su ; Ho, Jeong-Seok ;
Journal of Korea Water Resources Association, volume 30, issue 5, 1997, Pages 477~485
Recent internal and external bridge failures due to pier and abutment scour have emphasized the need for better methods of scour depth estimation. This paper compares the hydraulic analysis of the Namhan River Bridge over the Namhan River using one-dimensional models. WSPRO & HEC-2, and the two-dimensional model. TABS-MD based on the procedures presented in HEC-18 published by the U.S. FEdral Highway Administration. A comparison of estimated scour depth for this research based on the results from both one-dimensional and two-dimensional model is presented. At the same time, field measurement has been performed before and after flood using sounding instrument. Fathometer (DE-719C). A comparison between estimated and measured scour depth at bridge is also presented. Result shows that there is all the difference between estimated and measured scour depth due to dissimilarity between laboratory and field conditions. Also, it is difficult to measure the maximum scour depth accurately due to refilling. Therefore development of scour measuring equipment which can be used during peak flood, and derivation of empirical model appropriate for internal river system seems urgent.
Maximum Run-Up Height of Single Waves
Jo, Yong-Sik ; Lee, Bong-Hui ;
Journal of Korea Water Resources Association, volume 30, issue 5, 1997, Pages 487~493
The maximum run-up heights of single waves are investigated in this study. A boundary intergral equation model is used to calculate the maximum urn-up heights of both solitary and N-waves. The effect of the bottom friction is considered in the model through a boundary layer theory. The calculated run-up heights are compared with available laboratory measurements, and other numerical and approximate analytical solutions. They are in good agreement.
Explicit Design of Commercial Pipe on a Slope with Pumping Power
Yu, Dong-Hun ; Gang, Chan-Su ;
Journal of Korea Water Resources Association, volume 30, issue 5, 1997, Pages 495~501
Pumping power being given, traditional method requires an iteration process for the solution of discharge and pipe diameter. Yoo and Kang (1996) have developed explicit equations for the estimation of discharge and pipe diameter for the cases of uniformly rough pipe on a sloping bed with a pumping power. The use of poser law for the estimation of friction factor enabled to develop the explicit form of equations. Yoo (1995a) has suggested the mean friction factor method for the estimation of friction factor of commercial pipe or composite surface pipe. With the same approach, the present work has developed the explicit equations of discharge or pipe diameter for the general case of commercial pipe on a sloping bed with a pumping power by adopting the mean friction factor method.
Measurement and Modelling of Rainfall Interception in Quercus mongolica and Pinus rigitaeda during the Rainy Season
Kim, Gyeong-Ha ; U, Bo-Myeong ;
Journal of Korea Water Resources Association, volume 30, issue 5, 1997, Pages 503~514
A Study on the Rainfall-Runoff Analysis using the TOPMODEL
Jo, Hong-Je ; Jo, In-Ryul ; Kim, Jeong-Sik ;
Journal of Korea Water Resources Association, volume 30, issue 5, 1997, Pages 515~526
A Study on the Reliability Analysis for Water Supply on Reservoir System
Sim, Myeong-Pil ; Lee, Bong-Hui ; Kim, Gyeong-Tak ;
Journal of Korea Water Resources Association, volume 30, issue 5, 1997, Pages 527~537
Reliability, resiliency and vulnerability for the risk analysis are mathematically defined as the evaluation standard of risk level to characterize the risk which influences water resources management and optimal reservoir operations. Monthly inflows are synthetically generated by stochastic generation model for a long-term reservoir water budget analysis, and this method is applied to the Dae-Cheong Multipurpose Dam. As a result of study, reliability based on occurrence, time and quantity are derived respectively. Also resiliency, vulnerability and resiliency inc\dices are estimated to evaluate the performance of water supply on reservoir system, and their relationships are evaluated.
Application of TOPMODEL at Artificially Drained Watershed
Kim, Sang-Hyeon ;
Journal of Korea Water Resources Association, volume 30, issue 5, 1997, Pages 539~548
A physically based model for rainfall runoff simulation in agricultural watershed equipped with tile drains is presented. This model is developed from the TOPMODEL which is based on the detailed topographic information provided by Digital Elevation Model (DEM). Nine possible flow generation scenarios in the tile drained basin are suggested and used in the development of the model. The model can identify the portions of the hydrograph resulting from tile flow, subsurface flow and surface flow. The performance of the model is assessed through a calibration and validation process. The results of the analysis show that the model describes the physical system well and provides a better insight into the hillslope hydrology of agricultural watersheds with tile drainage.
Unsteady Flow Model for the Main Reach of the Han River : Calibration
Hwang, Ui-Jun ; Jeon, Gyeong-Su ;
Journal of Korea Water Resources Association, volume 30, issue 5, 1997, Pages 549~559
A multiply-connected network unsteady flow model for the main reach of the Han River is developed. It is a variable parameter model which allows variable roughness coefficient for each computational point according to the spatial position and the value of discharge. Sensitivities of the model to roughness coefficient and weir-flow discharge coefficient are tested, and as a result Manning's roughness coefficient is selected as the calibration parameter. The model is calibrated and verified using the records of the past flood events. A modified Gauss-Newton method is used for the optimal calibration of roughness coefficients. From the calibration of variable parameter model, spatial variation and discharge dependence of Manning's roughness coefficient are identified. That is, the roughness coefficient is higher for the upstream reach of the Wangsook stream Junction, and it decreases as the discharge increases. It turns out through the verification that the stages calculated by the variable parameter model agree better with the observed than those by the conventional single parameter model. Spatial variation of the roughness coefficient appears to be more significant than the dependence of the discharge
Estimation of Sediment Transport and Influence Factor for the Prediction of Riverbed Changes
Yun, Se-Ui ; Lee, Jong-Tae ; Jeong, Jae-Uk ;
Journal of Korea Water Resources Association, volume 30, issue 5, 1997, Pages 561~570
The feature of this paper is (1) to analyze the characteristics of rainfall-runoff relationship with kinematic wave theory, (2) to study the computational model to estimate the sediment yield, (3) to analyze the effects of bed change by transport formulas and the number of watershed division, and (4) to verify the model application with observation of channel data and measurement of rainfall, runoff, sediment discharge in Pyung-Chang River Basin. The calculated time of concentration of peak discharge occured little earlier than the actual, but the tendency of hydrograph coincided with observation. The shape of sediment hydrographs was similar to the water hydrograph. Based on above results, the applicability of the model was verified in detail. As the number of watershed division increased, the difference between the measured runoff and sediment values and the estimated ones decreased. The result of calculation with Yalin's formula for surface and Acker-White's one for channel gave the best agreement with the measured data among the six selected sediment transport foumulas.