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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 43, Issue 12 - Dec 2010
Volume 43, Issue 11 - Nov 2010
Volume 43, Issue 10 - Oct 2010
Volume 43, Issue 9 - Sep 2010
Volume 43, Issue 8 - Aug 2010
Volume 43, Issue 7 - Jul 2010
Volume 43, Issue 6 - Jun 2010
Volume 43, Issue 5 - May 2010
Volume 43, Issue 4 - Apr 2010
Volume 43, Issue 3 - Mar 2010
Volume 43, Issue 2 - Feb 2010
Volume 43, Issue 1 - Jan 2010
Selecting the target year
Optimization of Water Reuse System under Uncertainty
Chung, Gun-Hui ; Kim, Tae-Woong ; Lee, Jeong-Ho ; Kim, Joong-Hoon ;
Journal of Korea Water Resources Association, volume 43, issue 2, 2010, Pages 131~138
DOI : 10.3741/JKWRA.2010.43.2.131
Due to the increased water demand and severe drought as an effect of the global warming, the effluent from wastewater treatment plants becomes considered as an alternative water source to supply agricultural, industrial, and public (gardening) water demand. The effluent from the wastewater treatment plant is a sustainable water source because of its good quality and stable amount of water discharge. In this study, the water reuse system was developed to minimize total construction cost to cope with the uncertain water demand in future using two-stage stochastic linear programming with binary variables. The pipes in the water reuse network were constructed in two stages of which in the first stage, the water demands of users are assumed to be known, while the water demands in the second stage have uncertainty in the predicted value. However, the water reuse system has to be designed now when the future water demands are not known precisely. Therefore, the construction of a pipe parallel with the existing one was allowed to meet the increased water demands in the second stage. As a result, the trade-off of construction costs between a pipe with large diameter and two pipes having small diameters was evaluated and the optimal solution was found. Three scenarios for the future water demand were selected and a hypothetical water reuse network considering the uncertainties was optimized. The results provide the information about the economies of scale in the water reuse network and the long range water supply plan.
Computational Model for Flow in River Systems Including Storage Pockets with Side Weirs
Jun, Kyung-Soo ; Kim, Jin-Soo ; Kim, Won ; Yoon, Byung-Man ;
Journal of Korea Water Resources Association, volume 43, issue 2, 2010, Pages 139~151
DOI : 10.3741/JKWRA.2010.43.2.139
A quasi-two-dimensional unsteady flow model was developed for simulating the flow in a river system including artificial storage pockets with side weirs. It is a multiply-connected network which combines channels and storage pockets. The channel flow is described by the one-dimensional Saint Venant equations, and the weir overflow flow by the cell continuity and stage-discharge relations. The model was applied to the Imjin river system including six artificial storage pockets. Design flood peak reduction due to storage pockets is not sensitive to the side weir discharge coefficient. Storage pockets downstream are less effective than upstream ones in reducing peak stage as the backwater effect becomes more dominant. Simulated flood control effect is highly sensitive to the roughness coefficient. The uncertainty due to the roughness coefficient increases as the weir crest elevation gets higher. Because the best design alternative varies with the roughness coefficient, proper estimation of it is essential to the design of side weirs. Moreover, uncertainty of the estimation needs to be considered in the design process.
Identification of Factors Affecting Errors of Velocity Calculation on Application of MLSPIV and Analysys of its Errors through Labortory Experiment
Kim, Young-Sung ; Lee, Hyun-Seok ;
Journal of Korea Water Resources Association, volume 43, issue 2, 2010, Pages 153~165
DOI : 10.3741/JKWRA.2010.43.2.153
Large-Scale Particle Image Velocimetry (LSPIV) is an extension of particle image velocimetry (PIV) for measurement of flows spanning large areas in laboratory or field conditions. LSPIV is composed of six elements - seeding, illumination, recording, image transformation, image processing, postprocessing - based on PIV. Possible error elements at each step of Mobile LSPIV (MLSPIV), which is a mobile version of LSPIV, in field applications are identified and summarized the effect of the errors which were quantified in the previous studies. The total number of elemental errors is 27, and five error sources were evaluated previously, seven elemental errors are not effective to the current MLSPIV system. Among 15 elemental errors, four errors - sampling time, image resolution, tracer, and wind - are investigated through an experiment at a laboratory to figure out how those errors affect to velocity calculation. The analysis to figure out the effect of the number of images used for image processing on the velocity calculation error shows that if over 50 images or more are used, the error due to it goes below 1 %. The effect of the image resolution on velocity calculation was investigated through various image resolution using digital camera. Low resolution image set made 3 % of velocity calculation error comparing with high resolution image set as a reference. For the effect of tracers and wind, the wind effect on tracer is decreasing remarkably with increasing the flume bulk velocity. To minimize the velocity evaluation error due to wind, tracers with high specific gravity is favorable.
A Study on Design Flood Analysis Using Moving Storms
Oh, Kyoung-Doo ; Lee, Soon-Cheol ; Ahn, Won-Sik ; Ryu, Young-Hoon ; Lee, Joon-Hak ;
Journal of Korea Water Resources Association, volume 43, issue 2, 2010, Pages 167~185
DOI : 10.3741/JKWRA.2010.43.2.167
One of the most difficult problems in estimating design floods is how to determine design storms. More specifically, the design storm problems turn into how to determine temporal and spatial distribution of the storm. In this study, Thiessen-Weighted BlocKing-type(TWBK) moving storms are suggested to resolve the design storm problems and their applicability is investigated. These moving storms are applied for 100-year 48-hour design flood estimation in Han river basin using a physics-based distributed rainfall-runoff model. Simulated floods from moving storms are compared with frequency-based ones estimated from observed floods.
Evaluation of Probability Rainfalls Estimated from Non-Stationary Rainfall Frequency Analysis
Lee, Chang-Hwan ; Ahn, Jae-Hyun ; Kim, Tae-Woong ;
Journal of Korea Water Resources Association, volume 43, issue 2, 2010, Pages 187~199
DOI : 10.3741/JKWRA.2010.43.2.187
This study evaluated applicability and confidence of probability rainfalls estimated by the non-stationary rainfall frequency analysis which was recently developed. Using rainfall data at 4 sites which have an obvious increasing trend in observations, we estimated 3 type probability rainfalls; probability rainfalls from stationary rainfall frequency analysis using data from 1973-1997, probability rainfalls from stationary rainfall frequency analysis using data from 1973-2006, probability rainfalls from non-stationary rainfall frequency analysis assuming that the current year is 1997 and the target year is 2006. Based on the comparison of residuals from 3 probability rainfalls, the non-stationary rainfall frequency analysis provided more effective and well-directed estimates of probability rainfalls in the target year. Using Bootstrap resampling, this study also evaluated the parameter estimation methods for the non-stationary rainfall frequency analysis based on confidence intervals. The confidence interval length estimated by the maximum likelihood estimation (MLE) is narrower than the probability weighted moments (PWM). The results indicated that MLE provides more proper confidence than PWM for non-stationary probability rainfalls.
Estimation of the Reliability of Water Distribution Systems using HSPDA Model and ADF Index
Baek, Chun-Woo ; Jun, Hwan-Don ; Kim, Joong-Hoon ;
Journal of Korea Water Resources Association, volume 43, issue 2, 2010, Pages 201~210
DOI : 10.3741/JKWRA.2010.43.2.201
In this study, new methodology to estimate the reliability of a water distribution system using HSPDA model is suggested. In general, the reliability of a water distribution system can be determined by estimating either the ratio of the required demand to the available demand or the ratio of the number of nodes with sufficient pressure head to the number of nodes with insufficient pressure head when the abnormal operating condition occurs. To perform this approach, hydraulic analysis under the abnormal operating condition is essential. However, if the Demand-Driven Analysis (DDA) which is dependant on the assumption that the required demand at a demand node is always satisfied regardless of actual nodal pressure head is used to estimate the reliability of a water distribution system, the reliability may be underestimated due to the defect of the DDA. Therefore, it is necessary to apply the Pressure-Driven Analysis (PDA) having a different assumption to the DDA`s which is that available nodal demand is proportion to nodal pressure head. However, because previous study used a semi-PDA model and the PDA model which had limited applicability depending on the characteristics of a network, proper estimation of the reliability of a water distribution system was impossible. Thus, in this study, a new methodology is suggested by using HSPDA model which can overcome weak points of existing PDA model and Available Demand Fraction (ADF) index to estimate the reliability. The HSPDA can simulate the hydraulic condition of a water distribution system under abnormal operating condition and based on the hydraulic condition simulated, ADF index at each node is calculated to quantify the reliability of a water distribution system. The suggested model is applied to sample networks and the results are compared with those of existing method to demonstrate its applicability.
Urban Flood Simulation Considering Buildings Resistance Coefficient Based on GIS: Focused on Samcheok City
Ji, Juong-Hwan ; Kang, Sang-Hyeok ;
Journal of Korea Water Resources Association, volume 43, issue 2, 2010, Pages 211~220
DOI : 10.3741/JKWRA.2010.43.2.211
The objective of this paper presents the application of an "integrated urban flood modeling-runoff model, urban flood model and sewer system model-" in a highly urbanized area of Samcheok where is seriously inundated in 2002 and 2003. For this, we demonstrate how couple a 1-D hydrodynamic model of the river, a 2-D hydrodynamic model of the overland (surface) flow, and a sewer network model including each boundary conditions. In order to make data file for the model, topographic information like elevation and share rate of buildings are directly extracted from DEM or topographical source data without data exchange to avoid uncertainty errors. Furthermore, the research is to assess the impacts of Manning n and buildings influences to inundated depth by changing its share ratio from 10 % to 30 % in low-land urban area. As a results, we found out that the urban inundated depth was decreased by Manning n but increased by buildings ratio. The calculated results of inundation was similar with observed one in 2002 and 2003 flooding. Furthermore, the area was also inundated under not riverbank break case in 2002 flooding.
Development of Urban Flood Water Level Forecasting Model Using Regression Method
Jeong, Dong-Kug ; Lee, Beum-Hee ;
Journal of Korea Water Resources Association, volume 43, issue 2, 2010, Pages 221~231
DOI : 10.3741/JKWRA.2010.43.2.221
A regression water level forecasting model using data from stage and rainfall monitoring stations is developed to solve the difficulties which real-time forecasting models could not get the reliabilities by assuming future rainfall duration and intensity. The model could forecast future water levels of maximum 2 hours after using data from monitoring stations in Daejeon area. It shows stable forecasts by its maximum standard deviation is 5 cm, average standard deviations are 1~4 cm and most of coefficients of determination are larger than 0.95. It shows also more researches about the stationary of watershed which assumed in this regression method are necessary.
Estimation of Muskingum-Cunge Parameters for Natural Streams
Kim, Jin-Soo ; Jun, Kyung-Soo ;
Journal of Korea Water Resources Association, volume 43, issue 2, 2010, Pages 233~243
DOI : 10.3741/JKWRA.2010.43.2.233
A method is proposed of estimating Muskingum-Cunge parameters for natural streams using cross-sectional and longitudinal channel geometry and roughness coefficient data. Firstly, for various water-surface levels at a cross section cross-sectional areas and hydraulic radii are calculated. Corresponding discharges are then calculated using Manning`s equation. This procedure is repeated for all cross-sections in the reach. Finally, routing parameters are estimated from the calculated cross-sectional area and discharge value pairs by regression analysis. The procedures for estimating Muskingum-Cunge parameters are applied to the South Han River. Flows calculated by Muskingum-Cunge model with estimated parameters showed much better agreement with those by dynamic wave model in peak discharge, time to peak discharge, and normalized RMS errors than those calculated by the HEC-1 Muskingum-Cunge model.