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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 28, Issue 3 - 00 1995
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Hydraulic Flood Routing for Natural Channels
박기호 ; 조현경 ; 지홍기 ; 이순탁 ;
Journal of Korea Water Resources Association, volume 28, issue 3, 1995, Pages 113~113
A nonlinear wave routing model is suggested for the routing of floods in the natural open channel networks. For the optimization of parameter of the proposed routing model, parameter adjustment is executed through the proposed objective function. The model treats backwater effect form upstream and downstream ends. Solution of formulated model is made possible on computer by adopting a nonlinear finite-difference scheme for the numerical analysis based on a combination of Lax-Wendroff scheme and Burstein-Lapidus modification. Comparison of the results of the proposed model to those of actual hydrograph and dynamic wave routing model denotes that the proposed model is as accurate as actual runoff hydrograph and faster the computer time than the dynamic wave routing model.
Development of Flow Forecasting System in Large Drainage Basin
Journal of Korea Water Resources Association, volume 28, issue 3, 1995, Pages 123~123
The subject research attempts to develop a hydrologic-hydraulic forecasting system suitable for use in large river basins. A conceptual hydrologic rainfall-runoff model is used to produce streamflow from meteorological and hydrologic input data over each subbasin, while a hydraulic model is used to route the catchment outflows in the stream network. For operational flow prediction, an efficient state estimator has been designed for the real-time updating of model states from newly recorded data. The real-time application of the forecasting system indicates that this model produces reliable short-term predicted results.
The Influence of Lake Position on Groundwater Fluxes
Journal of Korea Water Resources Association, volume 28, issue 3, 1995, Pages 133~133
The purpose of this study is to investigate the influence of the position of lake upon groundwater fluxes on a lake watershed, and to provide the guidance for the monitoring network design to survey the exchange relations between grondwater and lake water. Three kinds of hypothetical flow through lakes, which are located at the upper, middle, and lower portion of a watershed were considered. And groundwater flow for each case was numerically simulated under three-dimensional steady state conditions. As a result, it can be shown that: (1) The exchange between lake and groundwater in the case where a lake is located at lower portion on watershed shows more active than that for a lake located at upper portion. (2) The amounts of inflow from groundwater to a lake are less than the amounts of discharge to groundwater in a target lake watershed. (3) The rate of inflow and outflow of groundwater to a lake is increased as the lake is located at upper portion of a watershed. (4) The horizontal flux of groundwater occurred on the lake bed is more significantly active than the vertical flux.
Precipitation Change in Korea due to Atmospheric CO₂ Increase
오재호 ; 홍성길 ;
Journal of Korea Water Resources Association, volume 28, issue 3, 1995, Pages 143~143
A precipitation change in Korea due to atmospheric CO₂ doubling has been estimated with a mixed method(Robinson and Finkelstein, 1991) to represent regional precipitation distribution from the simulated precipitation data by three GCM(general circulation model) (CCC, UI, and GFDL GCM) experiments. As a result of this analysis, the precipitation change by atmospheric CO₂ doubling can be summarized as follows: The precipitation increases as much as 25mm/yr during spring season and more than 50mm/yr during summer and autumn. However, it decreases as much as 13mm/yr during winter. In terms of percentage with respect to current precipitation climatology, we may have more rain as much as 10%, 13% and 24%, respectively, for spring, summer and autumn than current precipitation. However, we may have less winter precipitation than current climatological average.
Characteristics of Runoff and Groundwater Quality from a Pasture and Field
최중대 ; 최예환 ; 김기성 ;
Journal of Korea Water Resources Association, volume 28, issue 3, 1995, Pages 175~175
Characteristics of runoff and groundwater qualities from a pasture and field were investigated. Flumes and monitoring wells were installed and water qualities of NO₃-N, TP and TKN were monitored from Aug. 1993 to Aug. 1994. Runoff from the pasture which was a sandy soil with cobbles mostly formed with seeping water at the bottom of it. But once overland flow occurred because of heavy rainfall, runoff increased sharply. NO₃-N concentration in pasture runoff was relatively stable ranging between 0.241-3.962mg/ℓ. TP and TKN concentrations were stable but sharply increased once overland flow occurred. NO₃-N concentration in pasture groundwater was relatively stable regardless of depth of monitoring wells but TP and TKN concentrations were smaller in deeper wells. Runoff from the field which was flat and covered well with Sudan grass and surface residue was relatively small and NO₃-N, TP and TKN concentrations in runoff were stable and seemed unaffected by flow rate. NO₃-N concentration in field groundwater increased at the rate of 2.2mg/ℓ per 100 m during a growing season as groundwater flows through the field. No significant differences in TP and TKN concentrations between the upper and lower areas in field groundwater were detected.
Hydrological Stability Analysis of the Existing Soyanggang Multi-Purpose Dam
고석구 ; 신용노 ;
Journal of Korea Water Resources Association, volume 28, issue 3, 1995, Pages 187~187
This study aims at suggesting an alternative to improve current capacity of flood control for the existing Soyanggang multi-purpose dam which was constructed 20 years ago as a largest dam in Korea. The newly estimated value of the probable maximum precipitation(PMP) is 760.0 mm which is based on the hydrometeorological method. The peak inflow of 1000 years return period at the time of construction was 13,500㎥/s. However, the newly estimated peak inflow of the PMF is 18,100㎥/s which is 1.34 times bigger than the original one. In order to adopt the newly estimated PMF as a design flood, following four alternatives were compared (1) allocation of more flood control space by lowering the normal high water level, (2) construction of a new spillway in addition to the existing one, (3) raising the existing dam crest, (4) construction of a new dam which has relevant flood control storage at the upstream of the Soyanggang multipurpose dam. The preliminary evaluation of these alternatives resulted in that the second alternative is most economical and feasible. So as to stably cope with the newly estimated PMF by meeting all the current functions of the multi-purpose dam, a detailed study of an additional spillway tunnel has to be followed.
Experimental Study on the Depth-Variations of Confluence Area in Small Urban Channel
심기오 ; 이길춘 ;
Journal of Korea Water Resources Association, volume 28, issue 3, 1995, Pages 197~197
The runoff from an urban catchment is increased because of the gravitation of the population towards cities. For this reason, water level increment in confluence area makes it impossible to drain internal water and thus produces flood out in upstream areas. In this study, flow variations of main channel are measured which is caused by combining storm sewer into main channel in small watershed. Depth increment in main stream is analyzed due to flowrate and slope in main channel and flowrate, slope is getting steeper, and also due to low flowrate in main stream and high flowrate in tributrary channel. For the degree of confluence, depth ratio decreases when the degree is getting small. As mentioned above, main factors influencing the depth ratio increment of confluence channel are in the order of the degree of confluence, and the flowrate of tributary channel and main channel.
Analysis of Longitudinal Dispersion Coefficient: Part I. Comparative Study of Existing Equations for Dispersion Coefficient
서일원 ; 정태성 ;
Journal of Korea Water Resources Association, volume 28, issue 3, 1995, Pages 205~205
Existing equations for dispersion coefficient are analyzed in depth to select proper dispersion coefficient which can represent dispersion characteristics of natural streams. Several equations are tested with measured data which were collected in 26 streams in the United States. Findings of this study are as follows. Elder's equation should not be used to estimate dispersion coefficient of the one-dimensional dispersion model because it underestimates significantly. McQuivey and Keefer's equation is overestimating, whereas Magazine et al.'s equation is underestimating. However, Iwasa and Aya's equation predicts relatively well. Fischer's equation is generally overestimating. Liu's equation predicts quite well. The performance of Liu's equation is the best of all especially in terms of accuracy. However, Liu's equation is generally overestimating in case of large river because the square of channel width is included in the equation. Therefore, it is recommended not to use Liu's equation in case of large rivers, especially rivers of which channel width is larger than 200m.