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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
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A Research on the Daily Runoff Simulation for the Downstream Region of Multipurpose Dams in the Han River
Lee, Sang-Ho ; Kim, Yeong-Seong ; Sin, Yong-No ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 575~585
A daily runoff system was constructed to support decision making for water use in the downstream region of multipurpose dams in the Han River. The daily runoff system used the modified model from NWSRFS by Tabios III et al. (1986), and potential evapotranspiration was computed from Penman equation. DWOPER was used for channel routing. While the North Han River is the main river reach in the channel routing system, the South Han River and the Soyang River became tributaries. The rainfall-runoff model was calibrated and verified for five subbasins. Daily runoffs were simulated with the hydrometeorological data in 1986 and1990. The simulations were performed from April to November, and the sum of computed discharges for seven or thirty days were compared with actual releases of the downstream dams. It showed the average absolute errors of 8.7 ~31.6%. The sum of total discharges were 10% or less. While stage errors were produced by 0.5 m or less at Yoju station in the ease of simulation from April to August in 1986, the errors kept under 0.2 m since September. In the simulation for 1990, we compared two simulation results. One is produced from real internal and downstream boundary conditions and the other is one from internal and downstream boundary conditions fixed arbitrarily. The two cases showed similar results.
Measurement of Soil Water Content by Time Domain Reflectometry
Park, Jae-Hyeon ; Yun, Seong-Yong ; Kim, Sang-Jun ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 587~595
Experimental study on unsaturated flow in the soil is important to understand the characteristics of the water flow. Measurement of unsteady-state water movement using the traditional equipment (e.g. tensiometer) has a problem that requires relatively a long response time. In this study a quick measurement method of soil water flow using TDR is introduced. TDR consists of an electronic function generator which generates a squared wave, and an oscilloscope which catches the reflected wave. The wave is reflected where both the impedance of the transmission line and the propagation velocity are changed. The water content can be obtained from the travel time measured by means of TDR because the dielectric constant is affected by the change of soil water content. From the result of TDR calibration. TDR measurement error for the oven dried soil was found to be less than 3.5%. This supports that TDR is a viable technique to measure the unsteady-state water movement.
Prediction MOdels for Channel Bed Evolution Due to Short Term Floods
Pyo, Yeong-Pyeong ; Sin, Cheol-Sik ; Bae, Yeol-Ho ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 597~610
One-dimensional numerical models using finite difference methods for unsteady sediment transport on alluvial river channel are developed. The Preissmann implicit scheme and the Lax-Wendroff two-step explicit scheme with the Method of Characteristics for water motion and a forward time centered space explicit scheme for sediment motion are developed to simulate the sediment transport rate and the variation of channel bed level. The program correctness of each model is successfully verified using volume conservation tests. The sensitivity studies show that higher peak stage level, steeper channel slope and longer flooding duration produce more channel bed erosion. and median grain size,
give maximum volume loss in this study. Finally, the numerical models are found to produce reasonable results from the various sensitivity tests which reveal that the numerical models have properly responded to the changes of each model parameter.
The Estimation of Design Tide Level over the West Coast of Korea Based on the Kriging Model
Lee, Jae-Hyeong ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 611~620
The history of Tidal Bench Mark(TBM) at four major tide observation stations on the the Korea West Coast is reviewed. The data concerned with the local mean sea level(LMSL), the datum level(DL), and TBM is collected and checked. The values of LMSL surveyed by Rural Development Corporation(RDC), Office of Hydrographic Affair(OHA), and Office of Port Affair(OPA) are compared so that their unbiased MSLs at four stations are determined. Kriging model is introduced to estimate the design levels for tide; DL, MSL, and high water spring tide(HWOST). The estimated design level is well fitted with the sample data. The value of the identified drifts increase with the latitude. The estimated semi-variograms
show self similarity. The values of the
for DL and HWOST are 0.005 times as much as the values of
Estimation of Suspended Solids Concentration Caused by Stream Bed Excavation Works through the Application of the Fickian Diffusion Model
An, Myeong-Gil ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 621~628
Excavation works on stream beds have been done for various reasons including aggregate collection, sediment dredging, bridge constructions, or laying pipes under the ground. These activities may cause significant loadings of SS (suspended solids) resulting in water pollution and other detrimental effects to the surrounding environment. This research investigates application potential of a fickian diffustion model, derived from two dimensional advection-diffusion equation through some simplifying assumptions, as a planning tool for the estimation of SS loadings from excavation works and evaluation fo pollution prevention measures in case that sophisticated numerical simulation models are not applicable due to various practical reasons. Through a case study of the Juncheon stream in the Donghae City on the Kangwondo Province, this study demonstrates applicability of the fickian diffustion model as a practical method for the preliminary estimation of Ss loadings from excavation works and evaluation of performance of fabrics made of synthetic fiber for the reduction of downstream SS concentration with deficient field data.
Large-Scale Multi-Reservoirs System Analysis for Water Budget Evaluation
Lee, Gwang-Man ; Lee, Jae-Eung ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 629~639
Many reservoirs have been constructed and operated for utilizing and controlling water in main rivers of Korea since 1960's. New reservoirs are planned to satisfy increasing water demands according to the National Long-Term Water Resources Development Plan, that will make the entire water resources system more complex. That means reasonable approach is necessary to review many alternatives for future policy decision making of water resources management. As an attempting to simplify the water problem of the large-scale reservoirs system with more than 10 reservoirs, two stages approach such as simulation approach(HEC-5) is first applied to medium and small reservoirs and the results are used as inputs to final optimization approach (IDP) including large reservoirs is used in the water budget analysis of Han river water resources. In addition, existing multi-purpose reservoirs and planned reservoirs in Han river are formulated into one system and DPSA is applied to solve the basin-wide water resources assessment problem.
How to Measure Nonlinear Dependence in Hydrologic Time Series
Mun, Yeong-Il ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 641~648
Mutual information is useful for analyzing nonlinear dependence in time series in much the same way as correlation is used to characterize linear dependence. We use multivariate kernel density estimators for the estimation of mutual information at different time lags for single and multiple time series. This approach is tested on a variety of hydrologic data sets, and suggested an appropriate delay time
at which the mutual information is almost zerothen multi-dimensional phase portraits could be constructed from measurements of a single scalar time series.
Prediction of Influence of Polluted Water Discharged from Saemankeum Lake
Kim, Dae-Geun ; Seo, Il-Won ; Baek, Gyeong-O ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 649~659
The influence of polluted water discharged from the Saemankeum Lake is predicted by using two-dimensional finite element model. The simulation results show that influence of the Polluted water to the northern part of the Kckunsan Islands is small during flood time. The reason is because lock gates are located in the south of the Kokunsan Islands so that tidal current directing north is blocked by these Islands. However, during the ebb time, the influence of the polluted water is extended to the whole southern part of the Kokunsan Islands. When the amount of ten percent of the total volume of polluted water is discharged from the Saemankeum Lake, equi-concentration contour line of one tenth of initial discharge concentration includes the inner area surrounded by Sinsi Island, Munyeo Island, Bian Island, and Daehang-Li. In general, peak concentration near the lock gates is found out to be higher during the spring tide than the neap tide.
Hydraulic Characteristics of Fluid-Granule Mixed Flow in Embankment of Noncohesive Materials Due to Overflow
Kim, Jin-Hong ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 661~669
This paper presents a theoretical analysis for a velocity profile of fluid-granule mixed flow and a sheet erosion of an embankment having noncohesive materials due to overflow. The velocity profile were obtained using the stress-strain relationships based on a grain-inertia regime and an erosion depth was obtained using dynamic Coulomb criterion. Experiments were performed to compare with theoretical values and fairly good agreements were found. Theoretical results on velocity profiles, which can be applied to any type of velocity profiles in a fluid-granule mixed flow, showed a considerable improvement for the existing theories on a debris flow. for a design purpose, formulas and figure diagrams for obtaining a velocity profile, an erosion depth, an overflow depth and a granular discharge were proposed for given values of a flood discharge, particle properties and embankment scale.
Practical Aspects of Microwave Surface Velocity Meter Applied to Measurements of Stream Discharges
Lee, Sang-Ho ; Kim, U-Gu ; Kim, Yeong-Seong ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 671~678
Water surface velocity meters with microwave were applied to stream discharge measurements and its practical aspects were evaluted. The rating of the surface velocity meters was performed through a carriage and a water tank for the ship model test. It gave5.5% or less errors of average measured velocities under the vertical tilt ang1e of 20
, or 45
. A surface velocity meter was used to measure flood velocities at Yoju bridge from 8:00 a.m. to 10:00 a.m. on August 26, 1995. The results showed that surface velocities ranged from 2 to 4 m/s. With the measured surface velocities multiplied by 0.85, the discharge was computed as 10,500 m
/s. It differed
2% or less from the value of a stage-discharge curve and that of an unsteady flow simulation. Although the measured data are used sparsely per 40 or 60 meters, the computed discharges do not give large variation. Stream discharge measurements were also performed under the normal condition without floods. With the known values of Taechong Dam releases. the depth averaging factors of velocity were calculated by 0.83~0.87. Although there are errors from wind action and inherent ones in the velocity meters, the research showed that surface velocity meters could be an simple and practical alternative for flood discharge measurements.
Risk Model for the Safety Evaluation of Dam and Levee : I. Theory and Model
Han, Geon-Yeon ; Lee, Jong-Seok ; Kim, Sang-Ho ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 679~690
The risk assessment model for hydrlolgic safety analysis of dam and levee in developed by using Monte-Carlo and AFOSM (Advanced First-Order Second-Moment) method. The fault tree analysis and four phases approach are presented for the safety eveluation of risk of dam and levee. The risk model consists of rainfall-runoff analysis, reservoir routing and channel routing considering the variations in the model parameter. For the rainfall-runoff analysis, KRRL method is adopted with 200-year precipitation and PMP (Probable Maximum Precipitation). Reservoir routing is performed by fourth order Runge-Kutta method and channel routing by standard step method. The suggested model will contribute to safety evaluation of dam and levee and their rehabilitation decision problem.
Risk Model for the Safety Evaluation of Dam and Levee: II. Application
Han, Geon-Yeon ; Lee, Jong-Seok ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 691~698
The risk assessment model for dam and levee is applied to a river where two adjacent dams are located in the upstream of the watershed. "A" dam is proven to be safe with 200-year precipitation and unsafe with PMP condition, whereas "B" dam to be safe with 200-year precipitation and PMP condition. The computed risk considering the uncertainties of the runoff coefficient. initial water depth and relevant data of the dam and spillway turn out to be equivalent results in Monte-Carlo and AFOSM method. In levee risk model, this study addresses the uncertainty of water surface elevation by Manning's equation. Monte-Carlo simulation with the variations of Manning's roughness coefficient is calculated by assuming that it follows atriangular distribution. The model can be used for preparing flood risk maps, flood warning systems, and establishing nation's flood disaster protection plan.
Derivation of the Effective Hydraulic Conductivity in Stratified Layered Soil Using Stochastic Approach
Yun, Seong-Yong ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 699~708
The effective unsaturated hydraulic conductivity in stratified soils is evaluated using a three-dimensional stochastic approach. Because of the disparity of the correlation scales in a stratified soil, the general stochastic equations are simplified. This allows analytical evaluation of generic expressions for the effective hydraulic conductivities. Simple asymptotic expressions, valid at particular ranges(wetting front, drying condition, wetting condition) of the mean flow characteristics, are also derived. An example of applying the derived theoretical result to a imaginaryl clay soil is presented. It reveals found that the effective unsaturated hydraulic conductivity showed large-scale hysteresis. Such large-scale hysteresis was produced by the spatial variability of hydraulic soil properties rather than hysteresis of the local parameters. In addition the results show that the effective hydraulic conductivities were larger in the case of accommodating heterogeneity of soil preperties rather than neglecting heterogeneity of soil properties.
Determination Scheme of Variable Restricted Water Level during Flood Period of Multipurpose Dam
Gwon, O-Ik ; Sim, Myeong-Pil ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 709~720
When flood control storage lacks for the reservoir operation of multipurpose dams during flood period, the additional flood control storage should be considered for the flexible use of limited storage capacity. Flood period is divided by meteorological characteristics in this study and the water levels for water demand and flood control are investigated for the divided flood period. Based on the investigations, we suggest the variable restricted water level(VRWL) from the considerations of water conservation and flood control which can determine dam operating water level during flood period. This paper presents an application of the methodology to determination of the VRWL during flood period at the Taechong Dam and the results are discussed.
An Analysis of Long-Term Bed Elevation Changes to Estimate Total Scour Depth at Bridge Site
Lee, Jae-Su ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 721~729
Total scour depth at a bridge is comprised of three components: long-term changes, contraction scour and local scour. Therefore, the analysis of long-term bed elevation changes is very important in the estimation of total scour depth at bridge sites. In this research, long-term bed elevation changes at the Namhan River Bridge are analysed using CHARIMA and HEC-6 models. The results show that, for 5-year steady normal stream flow, the bed elevation is aggreded by 45cm for CHARIMA model but degraded by 5cm for HEC-6 model. For 5-year unsteady flow, the bed elevation is changed greatly and it has a great influence on the estimation of total scour depth. Therefore, to make a proper estimation of total scour depth, not only contraction scour and local scour, but also long-term bed elevation changes should be estimated precisely.
Experimental Study on the Optimum Operation Conditions of Rapid Mixing Impellers for an Effective W.T.P. Design
Son, Gwang-Ik ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 731~741
Optimum design conditions of rapid mixing impellers for an effective Water Treatment Plant operation were experimentally studied by thorough examination of parameters, such as impeller type and detention time. which govern the removal efficiency of turbidity. It was found that the impeller type is one of the major parameters governing the economic power consumption and the efficiency of turbidity removal. The experimental results showed that not only the velocity gradient G but also a new design guide. so called mixing energy per unit volume of raw water, could be used as a design and operation guides for rapid mixing in W.T.P.
Examination on the Experimental Prediction of Scour Depths Caused by Jets
Son, Kwang-Ik ; Yoon, Se-Eui ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 743~751
A thorough literatural review of researches on the experimental prediction of scour depths caused by jets was carried out to find out a measure of scour prediction. A new experimental equation for predicting scour depths due to a vortical or an inclined jet was developed from five hundreds of experimental data which were carefully reviewed and adopted from the previous researches. The developed equation shows 0.941 statistical correlation coefficient. It was found that the parameters governing the scour depth were the size of bed material, flow rate through unit width of spillway, and head drop across structure. The predicted scour depth could be expressed as the deepest scouring depth below tail water surface with correlation coefficient
Development of an Accurate Numerical Model for Density-Dependent Groundwater Flow and Solute Transport
Park, Nam-Sik ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 753~759
A new numerical model was doveloped to simulate density-dependent ground water flow and solute transport. Accuracy of a numerical model depends upon how well it simulates advection dominant situations because numerical oscillations can spoil solutions for these situations. Nonlinear oscillation-absorption finite element method. based on the variational principle, was employed. Unlike previous numerical models, this model can easily be expanded for more complex situations. Accuracy of the model is evaluated by comparing with analytical solutions and results of other numerical model.
Development of Numerical Model for Unsteady Flow Analysis jin Discharge Culvert of Thermal Power Plant: I. Model Setup
Yun, Seong-Beom ; Lee, Gi-Hyeok ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 761~768
A numerical model is developed to analyze the incompressible unsteady flow induced by the pump trip-out in the cooling water discharge culvert of thermal power plants. The numerical models has various features to deal concureently with the overall behavior of complicated unsteady flow due to the presence of cooling water internal system, seal well, air chamber, culvert, manholes, open channel and sea water. A leap-frog finite difference scheme is employed to solve governing equations, and the model is tested for a simple case of two tanks connected with a pipe. A fixed free surface boundary condition used earlier at the downstream end of culvert for large water body is investigated.
Development of Numerical Model for Unsteady Flow Analysis jin Discharge Culvert of Thermal Power Plant: II. Model Application
Yun, Seong-Beom ; Lee, Gi-Hyeok ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 769~776
The behavior of surge induced in the discharge system of the thermal power plants by the sudden stop of cooling water pump is analyzed using the numerical model developed by Yoon and Lee (1997). Various effects, which are ignored earlier, such as discharge from internal system, air chamber and air inlet of seal well, monholes, open channel and sea are included. These effects of the surge behavior are systematically analyzed. Especially, the surge control effect and air pressure change in the air chamber associated with the area of air inlet are presented for easy application in practice.
Hydrological Characteristics of Subsurface Stormflow through Soil Matrix and Macropores on forested Hillslopes
Kim, Kyong-Ha ;
Journal of Korea Water Resources Association, volume 30, issue 6, 1997, Pages 777~785
This study was conducted to clarify the hydrological characteristics of subsurface flow through a soil matrix and macropores. The research facility was set up in a 20m-1ong trench excavated down to bedrock at the base of a hillslope in the Panola catchment under USGS Georgia district. 13 macropores were found on the trench face and 6 major macropores were monitored. Matrix and macropore flow were measured during 95.5mm rainfall on March, 6 to 7. 1996. Macropore flow had great influence on formation of peak flow because the delivery time to Peak flow of macropore flow were faster about 10hrs than those of matrix flow. Matrix flow continued to recess for 3 days. On the other hand, macropore flow stopped within 12hrs after the event ceased. This means that matrix flow controls the recession part. The spatial variations of matrix and macropore flow between each trough and collector were very large by a wide range of 8,655.3
. The bed rock surface topography relates closer with the spatial variations of the flow than the surface one.