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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 45, Issue 12 - Dec 2012
Volume 45, Issue 11 - Nov 2012
Volume 45, Issue 10 - Oct 2012
Volume 45, Issue 9 - Sep 2012
Volume 45, Issue 8 - Aug 2012
Volume 45, Issue 7 - Jul 2012
Volume 45, Issue 6 - Jun 2012
Volume 45, Issue 5 - May 2012
Volume 45, Issue 4 - Apr 2012
Volume 45, Issue 3 - Mar 2012
Volume 45, Issue 2 - Feb 2012
Volume 45, Issue 1 - Jan 2012
Selecting the target year
An Evaluation of Water Supply Reliability Using AWS Data in Korea
Moon, Jang-Won ; Choi, Si-Jung ; Kang, Seong-Kyu ; Lee, Jeong-Ju ;
Journal of Korea Water Resources Association, volume 45, issue 8, 2012, Pages 743~753
DOI : 10.3741/JKWRA.2012.45.8.743
AWS data can be used effectively to understand the rainfall characteristics in Korea. In spite of this advantage, AWS data have been used restrictively in flood control analysis and the study on water use analysis such as water balance assessment is very insufficient. In this study, AWS data are used to analyze spatial rainfall characteristics quantitatively and water balance assessment is performed based on AWS data. Water balance assessment is carried out from year 2002 to year 2010 considering water supply networks in Korea. The analysis shows that year 2009 is the driest year during 9 years (2002~2010) and the regions with low level water supply reliability are concentrated in the west coast of Jeonnam and the upper region of the Nakdong River. As a result, the regions that have a lack of available water resources such as the coastal and insular areas are vulnerable to droughts. Therefore, regional water supply and management plans are urgently needed. Additionally, AWS data, which consider rainfall characteristics of the coastal and insular areas, can be useful in water balance assessment.
Availability of Land Surface Temperature from the COMS in the Korea Peninsula
Baek, Jong-Jin ; Choi, Min-Ha ;
Journal of Korea Water Resources Association, volume 45, issue 8, 2012, Pages 755~765
DOI : 10.3741/JKWRA.2012.45.8.755
The Land Surface Temperature (LST) is one of the significant factors to understand the water and energy cycles between the land surface and atmosphere. However, few previous studies for spatio-temporal variations of LST has been investigated. In this study, we conducted comparative analyses between the Communication, Ocean and Meteorological Satellite (COMS) and MOderate-Resolution Imaging Spectroradiometer (MODIS) LST data. We compared COMS data with observations to identify the accuracy and found relative underestimated patterns of the COMS data as compared to observations. We also found that COMS LST were underestimated in compare to MODIS LST. The Terra LST was verified to have more similar trends with the COMS LST rather than Aqua LST. While we identified the applicability of COMS based on the results of similar tendencies of two comparisons, more intensive validation research at a variety of field conditions should be conducted to gurantee current COMS LST.
An Experimental Study for Reduction of Sedimentation Deposit in Combining Junction Manholes
Kim, Jung-Soo ; Kim, Kyoung-Beom ; Yoon, Sei-Eui ;
Journal of Korea Water Resources Association, volume 45, issue 8, 2012, Pages 767~782
DOI : 10.3741/JKWRA.2012.45.8.767
Accumulation of sediment within pipelines, manholes, and other components of urban sewer systems can have a bad influence on sewerage arrangements, such as the resistance of the passage of flows, the cause of urban flooding and the premature operation of combined sewer overflows, and the inevitable pollution of watercourses. Therefore, it is necessary to understand the movements and sedimentation of sediment loads in combining junction manholes by experiments. In this study, hydraulic experimental apparatus which can change the manhole shapes (square, circle) were installed to measure deposited sedimentation quantity. The quantity of deposited sediment loads was measured by different conditions, for instance, the inflow conditions of sediment (continuous and certain period), the amount of inflow sediment, and the variation of inflow pipe of sediment. The combining junction manhole that was set up a inclined benching have the considerable effect of reduction of sedimentation in manholes without apropos of the change of manhole shapes. Therefore, the improved manhole could be increased the drainage capacity of sewerage arrangements in urban sewer systems.
Development and Accuracy Analysis of the Discharge-Supply System to Generate Hydrographs for Unsteady Flow in the Open Channel
Kim, Seo-Jun ; Kim, Sang-Hyuk ; Yoon, Byung-Man ; Ji, Un ;
Journal of Korea Water Resources Association, volume 45, issue 8, 2012, Pages 783~794
DOI : 10.3741/JKWRA.2012.45.8.783
The analysis for unsteady flow is necessary to design the hydraulic structures affected by water level and discharge changes through time. The numerical model has been generally used for unsteady flow analysis, however it is difficult to acquire field data to calibrate and validate the numerical model. Even though it is possible to collect field data for some case, high cost and labor are required and sometimes it is considered that the confidence of measured data is very low. In this case, the experimental data for unsteady flow can be used to calibrate and validate the numerical model as an alternative. Therefore, the discharge-supply system which could generate various type of unsteady flow hydrograph was developed in this study. Also, the accuracy of the unsteady flow hydrograph generated by developed dischargesupply system in the experiment was evaluated by comparing with target hydrograph. Accuracy errors and Root Mean Square Error (RMSE) were analyzed for the rectangular-type hydrograph with sudden changes of flow, triangular-type hydrograph with short peak time, and bell-type flood hydrograph. As a result, the generating error of the discharge-supply system for the rectangular-type hydrograph was about 59% which was maximum error among various types. Also, it was represented that RMSE for the triangular-type hydrographs with single and double peaks were approximately corresponding to 10%. However, RMSE for the bell-type flood hydrograph was lower than 2%.
Evaluation of Runoff‧Peak Rate Runoff and Sediment Yield under Various Rainfall Intensities and Patterns Using WEPP Watershed Model
Choi, Jae-Wan ; Ryu, Ji-Chul ; Kim, Ik-Jae ; Lim, Kyoung-Jae ;
Journal of Korea Water Resources Association, volume 45, issue 8, 2012, Pages 795~804
DOI : 10.3741/JKWRA.2012.45.8.795
Recently, changes in rainfall intensity and patterns have been causing increasing soil loss worldwide. As a result, the water ecosystem becomes worse and crops yield are reduced with soil loss and nutrient loss with it. Many studies have been proposed to estimate runoff and soil loss to predict or decrease non-point source pollution. Although the USLE has been used for many years in estimating soil losses, the USLE cannot reflect effects on soil loss of changes in rainfall intensity and patterns. The WEPP, physically based model, is capable of predicting soil loss and runoff using various rainfall intensity. In this study, the WEPP model was simulated for sediment yield, runoff and peak runoff using data of 5, 10, 30, 60 minute term rainfall, Huff's method and design rainfall. In case of rainfall interval of 5 minutes and 60 minutes, the sediment and runoff values decreased by 24% and 19%, respectively. The peak rate runoff values decreased by 16% when rainfall interval changed from 5 minutes to 60 minutes, indicating the peak rate runoff values are affected by rainfall intensity to some degrees. As a result of simulating using Huff's method, all values (sediment yield, runoff, peak runoff) were found to be the greatest at third quartile. According to the analysis under various design rainfall conditions (2, 3, 5, 10, 20, 30, 50, 100, 200, 300 years frequency), sediment yield, runoff, and peak runoff of 906.2%, 249.4% and 183.9% were estimated using 2 year to 300 year frequency rainfall data.
Estimation of Average Terrestrial Water Storage Changes in the Korean Peninsula Using GRACE Satellite Gravity Data
Lee, Sang-Il ; Kim, Joon-Soo ; Lee, Sang-Ki ;
Journal of Korea Water Resources Association, volume 45, issue 8, 2012, Pages 805~814
DOI : 10.3741/JKWRA.2012.45.8.805
Most hydrologic data are obtained by ground observations. New observation methods are needed for some regions to overcome difficulties in accessibility and durability of long-term observation. In 2002, NASA launched twin satellites named GRACE which were designed to measure the gravitational field of the earth. Using the GRACE monthly gravity level-2 data, we calculated terrestrial water storage change (TWSC) of the Korean peninsula in various spatial smoothing radii (0 km, 300 km, 500 km). For the validation of GRACE-based TWSC, we compared it with land-based TWSC which was obtained using the ground observation data: precipitation and evaporation from WAMIS, and runoff from GLDAS. According to the mean square-error test, GRACE-based TWSC best fits the land-based one at 500 km smoothing radius. The variation of the terrestrial water storage in the Korean peninsula turned out to be 0.986 cm/month, which means that appropriate measures should be prepared for sustainable water resources management.
Trend Analysis of Extreme Precipitation Using Quantile Regression
So, Byung-Jin ; Kwon, Hyun-Han ; An, Jung-Hee ;
Journal of Korea Water Resources Association, volume 45, issue 8, 2012, Pages 815~826
DOI : 10.3741/JKWRA.2012.45.8.815
The underestimating trend using existing ordinary regression (OR) based trend analysis has been a well-known problem. The existing OR method based on least squares approximate the conditional mean of the response variable given certain values of the time t, and the usual assumption of the OR method is normality, that is the distribution of data are not dissimilar form a normal distribution. In this regard, this study proposed a quantile regression that aims at estimating either the conditional median or other quantiles of the response variable. This study assess trend in annual daily maximum rainfall series over 64 weather stations through both in OR and QR approach. The QR method indicates that 47 stations out of 67 weather stations are a strong upward trend at 5% significance level while OR method identifies a significant trend only at 13 stations. This is mainly because the OR method is estimating the condition mean of the response variable. Unlike the OR method, the QR method allows us flexibly to detect the trends since the OR is designed to estimate conditional quantiles of the response variable. The proposed QR method can be effectively applied to estimate hydrologic trend for either non-normal data or skewed data.
Bivariate Frequency Analysis of Rainfall using Copula Model
Joo, Kyung-Won ; Shin, Ju-Young ; Heo, Jun-Haeng ;
Journal of Korea Water Resources Association, volume 45, issue 8, 2012, Pages 827~837
DOI : 10.3741/JKWRA.2012.45.8.827
The estimation of the rainfall quantile is of great importance in designing hydrologic structures. Conventionally, the rainfall quantile is estimated by univariate frequency analysis with an appropriate probability distribution. There is a limitation in which duration of rainfall is restrictive. To overcome this limitation, bivariate frequency analysis by using 3 copula models is performed in this study. Annual maximum rainfall events in 5 stations are used for frequency analysis and rainfall depth and duration are used as random variables. Gumbel (GUM), generalized logistic (GLO) distributions are applied for rainfall depth and generalized extreme value (GEV), GUM, GLO distributions are applied for rainfall duration. Copula models used in this study are Frank, Joe, and Gumbel-Hougaard models. Maximum pseudo-likelihood estimation method is used to estimate the parameter of copula, and the method of probability weighted moments is used to estimate the parameters of marginal distributions. Rainfall quantile from this procedure is compared with various marginal distributions and copula models. As a result, in change of marginal distribution, distribution of duration does not significantly affect on rainfall quantile. There are slight differences depending on the distribution of rainfall depth. In the case which the marginal distribution of rainfall depth is GUM, there is more significantly increasing along the return period than GLO. Comparing with rainfall quantiles from each copula model, Joe and Gumbel-Hougaard models show similar trend while Frank model shows rapidly increasing trend with increment of return period.
A Study on Evaluation of Water Supply Capacity with Coordinated Weirs and Multi-reservoir Operating Model
Chae, Sun-Il ; Kim, Jae-Hee ; Kim, Sheung-Kown ;
Journal of Korea Water Resources Association, volume 45, issue 8, 2012, Pages 839~851
DOI : 10.3741/JKWRA.2012.45.8.839
When we evaluate the water supply capacity of a river basin, it is a common practice to gradually increase the water demand and check if the water demands are met. This practice is not only used in the simulation approach, but also in the optimization approach. However, this trial and error approach is a tedious task. Hence, we propose a two-phase method. In the first phase, by assuming that the decision maker has complete information on inflow data, we use a goal programming model that can generate the maximum water supply capacity at one time. In the second phase, we simulate the real-time operation for the critical period by utilizing the water supply capacity given by the goal programming model under the condition that there is no foresight of inflow. We applied the two-phase method to the Geum-River basin, where multi-purpose weirs were newly constructed. By comparing the results of the goal programming model with those of the real-time simulation model we could comprehend and estimate the effect of perfect inflow data on the water supply capacity.