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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 31, Issue 6 - Dec 1998
Volume 31, Issue 5 - Oct 1998
Volume 31, Issue 4 - Aug 1998
Volume 31, Issue 3 - Jun 1998
Volume 31, Issue 2 - Apr 1998
Volume 31, Issue 1 - Feb 1998
Volume 21, Issue 3 - 00 1998
Selecting the target year
Development of an Expert System to Improve the Methods of Parameter Estimation
Lee, Beom-Hui ; Lee, Gil-Seong ;
Journal of Korea Water Resources Association, volume 31, issue 6, 1998, Pages 641~655
The methods of development and application of an expert system are suggested to solve more efficiently the problems of water resources and quality induced by the rapid urbanization. Major parameters of the water quantity and quality of urban areas are selected their characteristics are presented by the sensitivity analysis. The rules to decide the parameters effectively are proposed based on these characteristics. the ESPE(Expert System for Parameter Estimation), an expert system based on the 'facts' and 'rules', is developed using the CLIPS 6.0 and applied to the basin of the An-Yang stream. The results of estimating t도 parameters of water quantity show a high applicability, but those of water quality imply the necessity of improving the present methods due to both the complexity of estimation processes and the lack of decision rules.
Quantified Diagnosis of Flood Possibility by Using Effective Precipitation Index
Byeon, Hui-Ryong ; Jeong, Jun-Seok ;
Journal of Korea Water Resources Association, volume 31, issue 6, 1998, Pages 657~665
New diagnosing method o flood possibility was proposed. The method can be processed by following steps: first, decide if current available water resources are above normal or not; second, compute a consecutive period above normal; third, precipitation is accumulate through the period; fourth, daily depletion (runoff and evapotranspiration) amount is subtracted from the accumulated precipitation and remains are translated to one day's precipitation, which is called effective precipitation; and finally, effective precipitation index. the larger effective precipitation index means the higher flood possibility. This method has been applied to the flood event occurred in the central region of Korea at late July 1996 and compared with the study by Korea Water resources Association (1996). The new method is proven to be much faster in computation, and therefore much better in practical use for emergency situation than current rainfall-runoff models. It is because the new method simplifies some steps of currently used method such as parameter estimation and water level observation. It is also known that new method is more scientific than any other methods that use accumulated precipitation only as it considers the runoff depletion in time
Numerical Analysis of NAPL Removal from Soil and Groundwater Using Steam Injection
Lee, Sang-Il ;
Journal of Korea Water Resources Association, volume 31, issue 6, 1998, Pages 667~674
Numerical models simulating the process of NAPL from contaminated soil or groundwater through steam injection can be a useful tool for designing and evaluating the cleanup strategy under various field conditions. One and two dimensional numerical analyses were conducted based on the governing equations describing the NAPL removal as a non-isothermal, multi-phase and multi component process. Relatively good agreements were obtained between the numerical results and the observations from one-dimensional laboratory experiment, except some discrepancy due to experimental difficulties. Simulation effectively identified the steam displacement process of xylene floating on the water table and TCE sinking on the aquifer bottom in a two-dimensional analysis. Overall, simulation models have a high potential in the design/appraisal of a system for field application of the technique as well as in the examination of complex processes such as vaporization which is hard to identify experimentally.
Determination of Design Width for Medium Streams in the Han River Basin
Jeon, Se-Jin ; An, Tae-Jin ; Park, Jeong-Eung ;
Journal of Korea Water Resources Association, volume 31, issue 6, 1998, Pages 675~684
This paper presents the empirical formulas for determining the design-width for medium rivers in the Han river basin. The design flood, the watershed ares, and the channel slope of 216 medium rivers in the Han river basin are collected. the design width formulas are then determined by 1) the least squares (LS) method, 2)the least median squares (LMS) method, and 3) the reweighted least squares method based on the LMS (RLS). The six types of formulas are considered to determine the acceptable type for medium streams in the Han river basin. The root mean squared errors (RMSE), the absolute mean (AME) errors, and the mean errors (ME) are computed to test the formulas derived by three regression methods. It si found that the equation related stream width to the watershed area and the channel slope is acceptable for determining the design width for medium streams in the Han river basin. It is expected that the equations proposed by this study be used an index for determining the design-width for medium streams in the Han river basin.
Applicability of Groundwater Quality Monitoring Network Design Methodologies
Lee, Sang-Il ;
Journal of Korea Water Resources Association, volume 31, issue 6, 1998, Pages 685~694
Protection of groundwater resources from contamination has been of increasing concern throughout the past decades. In practice, however, groundwater monitoring is performed based on the experience and intuition of experts or on the convenience. In dealing with groundwater contamination, we need to know what contaminants have the potential to threat the water quality and the distribution and concentration of the plumes. Monitoring of the subsurface environment through remote geophysical techniques or direct sampling from wells can provide such information. Once known, the plume can be properly managed. Evaluation of existing methodologies for groundwater monitoring network design revealed that one should select an appropriate design method based on the purpose of the network and the availability of field information. Integer programming approach, one of the general purpose network design tools, and a cost to-go function evaluation approach for special purpose network design were tested for field applicability. For the sam contaminated aquifer, two approaches resulted in different well locations. The amount of information, however, was about the same.
A Sensitivity Analysis for Parameters Effection upon the Design Floods: Natural Watershed
Yun, Yeo-Jin ;
Journal of Korea Water Resources Association, volume 31, issue 6, 1998, Pages 695~708
Recently, it seems increasing trends that the design floods on the middle and small scale of urban regions and natural basins are evaluated with introducing to the concept of the critical storm duration. However the study of the critical storm duration is not sufficient and especially on the natural basins, it rarely performed. therefore in this study, estimated the critical storm duration and peak discharge according to the rainfall distribution type, the position of peak rainfall intensity, and the frequency on the natural basins were evaluated using Clark model and the influence of each factors on the design floods was analyzed with sensitivity analysis on the parameters of the model.
Urban Runoff and Water Quality Models
Lee, Jong-Tae ;
Journal of Korea Water Resources Association, volume 31, issue 6, 1998, Pages 709~725
The characteristics of storm and water quality are investigated based on the measuring data of the test river, the Hongje. the water quality of the test river is generally good comparing to other urban rivers in Seoul, because of the interception of sewer flow. But this system makes the river dry up for 3-4 months in winter. On the other hand, in rainy period the storm from the combined sewer system causes rapid increasing pollutants loads. In order to simulate the urban storm and water quality of the trest basin, the models such as SWMM, ILLUDAS, STORM, HEC-1 were applied and the results are compared in its applicability and accuracy aspects. All models discussed here have shown good results and it seems that SUMM is the most effective model in simulating both quantity and quality. Also, regression relations between the water quantity and quality were derived and their applicabilities were discussed. This regression model is a simple effective tool for estimating the pollutant loads in the rainy period, but if the amount of discharge is bigger than measuring range of raw data, the accuracy becomes poor. This model could be supplemented by expanding the range of collecting data and introducing the river characteristics. The HEC-1 would be anther effective model to simulate storm runoff of a river basin including urban area.
Optimal Reservour Operation for Flood Control Using a Hybrid Approach (Case Study: Chungju Multipurpose Reservoir in Korea)
Lee, Han-Gu ; Lee, Sang-Ho ;
Journal of Korea Water Resources Association, volume 31, issue 6, 1998, Pages 727~739
The main objectives o reservoir optimal operation can be described as follows : maximization of the benefits through optimal allocation of the limited water resources for various purpose; minimization of t도 costs by the flood damage in potential damaging regions and risk of dam failure, etc. through safe drainage of a bulky volume of excessive water by a proper reservoir operation. Reviewing the past research works related to reservoir operation, we can find that the study on the matter of the former has been extensively carried out in last decades rather than the matter of the latter. This study is focused on developing a methodology of optimal reservoir operation for flood control, and a case study is performed on the Chungju multipurpose reservoir in Korea. The final goal of the study is to establish a reservoir optimal operation system which can search optimal policy to compromise two conflicting objectives: downstream flood damage and dam safety-upstream flood damage. In order to reach the final goal of the study, the following items were studied : (1)validation of hydrological data using HYMOS: (2)establishment of a downstream flood routing model coupling a rainfall-runoff model and SOBEK system for 1-D hydrodynamic flood routing; (3)replication of a flood damage estimation model by a neural network; (4)development of an integrated reservoir optimization module for an optimal operation policy.
Regionalized Sensitivity Analysis of Extended TOPMODEL
Kim, Sang-Hyeon ;
Journal of Korea Water Resources Association, volume 31, issue 6, 1998, Pages 741~755
An extension of TOPMODEL was developed for rainfall-runoff simulation in agricultural watersheds equipped with tile drains. Tile drain functions are incorporated into the framework of TOPMODEL. Nine possible flow generation scenarios are suggested for tile drained watershed and applied in the modeling procedure. In the model development process, the traditional physically based storage approach and a new approach using a transfer function for the simulation of the flow in the unsaturated zone were compared. In order to provide better insight into the simulation process, a regionalized sensitivity analysis was performed to test the performance of the model and to compare the behavior of the transfer function to that of the simple storage related formulation. The results of analysis show good performance of the transfer function approach. Since the rainfall-runoff response pattern tends to vary seasonally, seven events distributed throughout a year were used in the sensitivity analysis to investigate the seasonal variation of the hydrologic characteristics. It is found that the sensitivity of each parameter described by the model are varied seasonally.
Study of Surges in a Large-Diameter Subteranean Diversion Channel with Multiple Surge Tanks
Jeong, Gwang-Geun ; Yeo, Un-Sik ; An, Tae-Jin ;
Journal of Korea Water Resources Association, volume 31, issue 6, 1998, Pages 757~768
rate of outflow is equated to the total rate of flow, both the state equation and its linearized equation yield almost identical oscillations of water levels. This shows that effects of pipe resistance on the surges are small, and justifies a free oscillation analysis. Free oscillation equation has six eigen modes of different periods, including a rigid mode which is existed when the pumped rate of outflow differs from the total rate of inflow. The six modes constitute a variety of surges dependent on different inflow and outflow conditions. Presence of the rigid mode needs sophisticated pump operations adjusted to real flood inflows.
BDS Statistic: Applications to Hydrologic Data
Kim, Hyeong-Su ; Gang, Du-Seon ; Kim, Jong-U ; Kim, Jung-Hun ;
Journal of Korea Water Resources Association, volume 31, issue 6, 1998, Pages 769~777
In this study, various time series are analyzed to check nonlinearities of the data. The nonlinearity of a system can be investigated by testing the randomness of the time series data. To test the randomness, four nonparametric test statistics and a new test statistic, called the BDS statistic are used and the results and the results are compared. The Brock, Dechert, and Scheinkman (BDS) statistic is originated from the statistical properties of the correlation integral which is used for searching for chaos and has been shown very effective in distinguishing nonlinear structures in dynamic systems from random structures. As a result of application to linear and nonlinear models which are well known, the BDS statistic is found to be more effective than nonparametric test statistics in identifying nonlinear structure in the time series. Hydrologic time series data are fitted to ARMA type models and the statistics are applied to the residuals. The results show that the BDS statistic can distinguish chaotic nonlinearity from randomness and that the BDS statistic can also be used for verifying the validity of the fitted model.
A Mathematical Model for Coordinated Multiple Reservoir Operation
Kim, Seung-Gwon ;
Journal of Korea Water Resources Association, volume 31, issue 6, 1998, Pages 779~793
In this study, for the purpose of water supply planning, we propose a sophisticated multi-period mixed integer programming model that can coordinate the behavior of multi-reservoir operation, minimizing unnecessary spill. It can simulate the system with operating rules which are self- generated by the optimization engine in the algorithm. It is an optimization model in structure, but it indeed simulates the coordinating behavior of multi-reservoir operation. It minimizes the water shortfalls in demand requirements, maintaining flood reserve volume, minimizing unnecessary spill, maximizing hydropower generation release, keeping water storage levels high for efficient hydroelectric turbine operation. This optimization model is a large scale mixed integer programming problem that consists of 3.920 integer variables and 68.658 by 132.384 node-arc incidence matrix for 28 years of data. In order to handle the enormous amount of data generated by a big mathematical model, the utilization of DBMS (data base management system)seems to be inevitable. It has been tested with the Han River multi-reservoir system in Korea, which consists of 2 large multipurpose dams and 3 hydroelectric dams. We demonstrated successfully that there is a good chance of saving substantial amount of water should it be put to use in real time with a good inflow forecasting system.
Evaluation of the Impact of Land Surface Condition Changes on Soil Moisture Field Evolution
Yu, Cheol-Sang ;
Journal of Korea Water Resources Association, volume 31, issue 6, 1998, Pages 795~806
Soil moisture is affected by regional climate, soil characteristics and land surface condition, etc,. Especially, the changes in land surface condition is more than other factors, which is mainly due to rapid urbanization and industrialization. This study is to evaluate how the change of land surface condition impacts on soil moisture field evolution using a simple model of soil moisture dynamics. For the quantification of soil moisture field, the first half of the paper is spared for the statistical characterization based on the first- and second-order statistics of Washita '92 and Monsoon '90 data. The second half is for evaluating the impact of land cover changes through simulation study using a model for soil moisture dynamics. The model parameters, the loss rate and the diffusion coefficient, have been estimated using the observed data statistics, where the changes of surface conditions are considered into the model by applying various parameter sets with different second-order statistics. This study is concentrated on evaluating the impact due to the changes of land surface condition variability. It is because we could easily quantify the impact of the changes of its areal mean based on the linear reservoir concept. As a result of the study, we found; (1)as the variability of land surface condition, increases, the soil moisture field dries up more easily, (2)as the variabilit y of the soil moisture field is the highest at the beginning of rainfall and decreases as time goes on to show the variability of land surface condition, (3)the diffusion effect due to surface runoff or water flow through the top soil layer is limited to a period of surface runoff and its overall impact is small compared to that of the loss rate field.
Relationships of El Ni o and La Ni a with both Temperature and Precipitation in South Korea
Lee, Dong-Ryul ;
Journal of Korea Water Resources Association, volume 31, issue 6, 1998, Pages 807~819
The relationships of El Nino and La Nina with both temperature and precipitation in South Korea is studied. Monthly temperature and precipitation are analyzed using harmonic analysis to identify region, magnitude and season that have responses associated with El Nino and La Nina. The first harmonic is extracted from a 24 month El Nino and La Nina composite at each station. The regions are identified by the similarity in the phase of the harmonic vectors. The responses of precipitation to El Nino and La Nina are found in the all regions. However, the response of precipitation to El Nino and La Nina is identified only in the southern region. In addition, statistical significance for response periods is investigated through cross correlation analysis. Once an El Nino and a La Nina event set in, the results of this analysis can provide an efficient information for the management of water resources, agriculture and environment.
A Study of Prediction of Daily Water Supply Usion ANFIS
Rhee, Kyoung-Hoon ; Moon, Byoung-Seok ; Kang, Il-Hwan ;
Journal of Korea Water Resources Association, volume 31, issue 6, 1998, Pages 821~832
This study investigates the prediction of daily water supply, which is a necessary for the efficient management of water distribution system. Fuzzy neuron, namely artificial intelligence, is a neural network into which fuzzy information is inputted and then processed. In this study, daily water supply was predicted through an adaptive learning method by which a membership function and fuzzy rules were adapted for daily water supply prediction. This study was investigated methods for predicting water supply based on data about the amount of water supplied to the city of Kwangju. For variables choice, four analyses of input data were conducted: correlation analysis, autocorrelation analysis, partial autocorrelation analysis, and cross-correlation analysis. Input variables were (a) the amount of water supplied (b) the mean temperature, and (c)the population of the area supplied with water. Variables were combined in an integrated model. Data of the amount of daily water supply only was modelled and its validity was verified in the case that the meteorological office of weather forecast is not always reliable. Proposed models include accidental cases such as a suspension of water supply. The maximum error rate between the estimation of the model and the actual measurement was 18.35% and the average error was lower than 2.36%. The model is expected to be a real-time estimation of the operational control of water works and water/drain pipes.
A Fundamental Study on the Snowmelt Effects for Long-Term Runoff Analysis
Bae, Deok-Hyo ;
Journal of Korea Water Resources Association, volume 31, issue 6, 1998, Pages 833~844
The objectives of this study are to adopt a snowmelt model for coupling a rainfall-runoff model and to study snowmelt effects for long-term runoff analysis on the northeast mountaneous area in Korea. The NWS temperature-index snowmelt model was selected and tested on the 1,059+,6 km
Naerinchen basin. It can be observed that the time variations of the computed areal extents of snow cover from the model are well agreement with those of the observe station snowfall records on the Inje meteorological station. It is also evident that the computed soil water contents and river flows indicate quite different behaviors with or without snowmelt model. It is concluded that the snowmelt model works well and the snowmelt effects for multi-decadal river flow computations are important on the study area.
Ebersole-Type Wave Transformation Model Usiog Extended Mild-Slope Equations
Jeong, Sin-Taek ; Lee, Chang-Hun ;
Journal of Korea Water Resources Association, volume 31, issue 6, 1998, Pages 845~854
Following the approach of Ebersole (1985), water wave transformation is predicted using the eikonal equation and transport equation for wave energy which are reduced from the extended mild-slope equation of Massel (1993), and also the irrotationality of wave number vectors. The higher-order bottom effect terms, i.e., squared bottom slope and bottom curvature, are neglected in the study of Ebersole but are included in the present study. It was expected that, if these terms are included in this study, the approach would give more accurate solution in the case of rapidly varying topography. But, the expectation was frustrated. It is probably because, in the case of rapidly varying topography, the diffraction effect which is included in the eikonal equation does not work well and thus the solution is deteriorated.
Sensitivity Analysis for Operation a Reservoir System to Hydrologic Forecast Accuracy
Kim, Yeong-O ;
Journal of Korea Water Resources Association, volume 31, issue 6, 1998, Pages 855~862
This paper investigates the impact of the forecast error on performance of a reservoir system for hydropower production. Forecast error is measured as th Root Mean Square Error (RMSE) and parametrically varied within a Generalized Maintenance Of Variance Extension (GMOVE) procedure. A set of transition probabilities are calculated as a function of the RMSE of the GMOVE procedure and then incorporated into a Bayesian Stochastic Dynamic Programming model which derives monthly operating policies and assesses their performance. As a case study, the proposed methodology is applied to the Skagit Hydropower System (SHS) in Washington state. The results show that the system performance is a nonlinear function of RMSE and therefor suggested that continued improvements in the current forecast accuracy correspond to gradually greater increase in performance of the SHS.