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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 49, Issue 8 - Aug 2016
Volume 49, Issue 7 - Jul 2016
Volume 49, Issue 6 - Jun 2016
Volume 49, Issue 5 - May 2016
Volume 49, Issue 4 - Apr 2016
Volume 49, Issue 3 - Mar 2016
Volume 49, Issue 2 - Feb 2016
Volume 49, Issue 1 - Jan 2016
Selecting the target year
One-month lead dam inflow forecast using climate indices based on tele-connection
Cho, Jaepil ; Jung, Il Won ; Kim, Chul Gyium ; Kim, Tae Guk ;
Journal of Korea Water Resources Association, volume 49, issue 5, 2016, Pages 361~372
DOI : 10.3741/JKWRA.2016.49.5.361
Reliable long-term dam inflow prediction is necessary for efficient multi-purpose dam operation in changing climate. Since 2000s the teleconnection between global climate indices (e.g., ENSO) and local hydroclimate regimes have been widely recognized throughout the world. To date many hydrologists focus on predicting future hydrologic conditions using lag teleconnection between streamflow and climate indices. This study investigated the utility of teleconneciton for predicting dam inflow with 1-month lead time at Andong dam basin. To this end 40 global climate indices from NOAA were employed to identify potential predictors of dam inflow, areal averaged precipitation, temperature of Andong dam basin. This study compared three different approaches; 1) dam inflow prediction using SWAT model based on teleconneciton-based precipitation and temperature forecast (SWAT-Forecasted), 2) dam inflow prediction using teleconneciton between dam inflow and climate indices (CIR-Forecasted), and 3) dam inflow prediction based on the rank of current observation in the historical dam inflow (Rank-Observed). Our results demonstrated that CIR-Forecasted showed better predictability than the other approaches, except in December. This is because uncertainties attributed to temporal downscaling from monthly to daily for precipitation and temperature forecasts and hydrologic modeling using SWAT can be ignored from dam inflow forecast through CIR-Forecasted approach. This study indicates that 1-month lead dam inflow forecast based on teleconneciton could provide useful information on Andong dam operation.
Redetermination of curve number using genetic algorithm and CN aligner equation
Park, Dong-Hyeok ; Kang, Doo-Sun ; Ahn, Jae-Hyun ; Kim, Tae-Woong ;
Journal of Korea Water Resources Association, volume 49, issue 5, 2016, Pages 373~380
DOI : 10.3741/JKWRA.2016.49.5.373
The NRCS-CN (Natural Resources Conservation Service-Curve Number) method has been practically applied for estimating the effective precipitation. However, there are no criteria which reflect the geographic characteristics of Korea having more than 70% of mountainous and rice paddy areas, leading to significant errors in runoff calculation. Thus, it is required to estimate the runoff curve number considered Korea land use classification, however there are practical difficulties to conduct the accurate research and experimentation. In this study, after selecting target areas (urban, agriculture, forest), we performed the runoff analysis to redetermine CN values for the selected basins. To do this, curve numbers for soil type A were estimated using genetic algorithm, and then curve numbers for soil type (B, C, D) were estimated using CN aligner equation. Comparing the initial curve numbers with the estimated curve numbers, it was observed that the slightly differences at Chunwang(0), Choonyang(-1), Janggi(-3). Through the above process, this study proposed new curve numbers to reflect observed rainfall-runoff.
Weighting assessment on evaluation indicators of dam rehabilitation using the AHP analysis
Choi, Ji-Hyeok ; Kim, Jong-Suk ; Kwon, Ji-Hye ; Moon, Young-Il ;
Journal of Korea Water Resources Association, volume 49, issue 5, 2016, Pages 381~389
DOI : 10.3741/JKWRA.2016.49.5.381
In this study, we developed evaluation indicators of dam rehabilitation considering climate change in order to prepare for safety of aging dam facilities in accordance with changes in rainfall intensity. The validity and appropriateness of each indicator, and the evaluation criteria were selected for quantitative indicators for each detail through domestic and international case studies, literature review, and expert advice. The survey was carried out to estimate the importance of each indicator for dam rehabilitation. The subjective assessment of the respondents was rearranged using pairwise comparison from the Analytic Hierarchy Process (AHP). The reliability of the survey results was evaluated through consistent verification. In addition, a comparative assessment was carried out which evaluated the reliability importance estimation result to refine the criteria to distinguish rating scales between expert and non-expert groups on dam-related fields.
Numerical analysis of lateral geomorphology changes by channel bed deposition and bank erosion at the river confluence section
Ji, Un ; Jang, Eun Kyung ;
Journal of Korea Water Resources Association, volume 49, issue 5, 2016, Pages 391~398
DOI : 10.3741/JKWRA.2016.49.5.391
The confluence section of rivers forms complex flow pattern due to inflow discharge variation at the mainstream and tributary. Due to complex flow characteristics, bed change and bank erosion at the local section produce lateral geomorphology changes in rivers. In this study, bankline change by bank erosion and bed change were simulated using CCHE2D of 2-dimensional numerical model for quantitative analysis of lateral changes in the confluence section of South Han River and Geumdang Stream. As a result, bankline at the left-side channel of the mainstream was largely changed in the downstream section of the confluence compared to the upstream section. Also, bank erosion in the tributary was hardly occurred and bankline at the left-side tributary and right-side main stream moved to riverside land due to decreased velocity and deposition.
Statistical analysis of hazen-williams C and influencing factors in multi-regional water supply system
Kim, Bumjun ; Kim, Gilho ; Kim, Hung soo ;
Journal of Korea Water Resources Association, volume 49, issue 5, 2016, Pages 399~410
DOI : 10.3741/JKWRA.2016.49.5.399
In case of the application of Hazen-Williams C for design, operation or maintenance of water supply system, field situations always should be reflected on the factors. In this study, the relationships between C factors and influencing factors are analyzed using statistical techniques with 174 measured C factor data collected in periodic inspection for safety diagnosis in multi-regional water supply systems. To analyze their relationships, cross analysis, one-way ANOVA, correlation analysis were conducted. Analysis results showed that C factors had high correlations with both of elapsed year and pipe diameter and were relatively highly affected by coating material among influencing factors with the categorical type. On the other hand, elapsed year, pipe diameter and water type were meaningful influencing factors according to the results of multiple regression analysis. The Cluster analysis revealed that C factors had a tendency of being fundamentally classified on the basis of the elapsed year of about 20 years and the pipe diameter of 1500mm. Although C factors were generally greatly affected by elapsed year, size of pipe diameter relatively had an large influence on values of them in case of large diameter pipes. Lastly, It can be suggested that C factor estimation formulas using multiple regression analysis and clustering analysis in this study, can be applied as decision standards of C factor in multi-regional water supply systems.
Assessment of uncertainty associated with parameter of gumbel probability density function in rainfall frequency analysis
Moon, Jang-Won ; Moon, Young-Il ; Kwon, Hyun-Han ;
Journal of Korea Water Resources Association, volume 49, issue 5, 2016, Pages 411~422
DOI : 10.3741/JKWRA.2016.49.5.411
Rainfall-runoff modeling in conjunction with rainfall frequency analysis has been widely used for estimating design floods in South Korea. However, uncertainties associated with underlying distribution and sampling error have not been properly addressed. This study applied a Bayesian method to quantify the uncertainties in the rainfall frequency analysis along with Gumbel distribution. For a purpose of comparison, a probability weighted moment (PWM) was employed to estimate confidence interval. The uncertainties associated with design rainfalls were quantitatively assessed using both Bayesian and PWM methods. The results showed that the uncertainty ranges with PWM are larger than those with Bayesian approach. In addition, the Bayesian approach was able to effectively represent asymmetric feature of underlying distribution; whereas the PWM resulted in symmetric confidence interval due to the normal approximation. The use of long period data provided better results leading to the reduction of uncertainty in both methods, and the Bayesian approach showed better performance in terms of the reduction of the uncertainty.
Evaluation of satellite-based soil moisture retrieval over the korean peninsula : using AMSR2 LPRM algorithm and ground measurement data
Kim, Seongkyun ; Kim, Hyunglok ; Choi, Minha ;
Journal of Korea Water Resources Association, volume 49, issue 5, 2016, Pages 423~429
DOI : 10.3741/JKWRA.2016.49.5.423
This study aims at assessing the quality of the Advanced Microwave Scanning Radiometer 2 (AMSR2) soil moisture products onboard GCOM-W1 satellite based on Land Parameter Retrieval Model (LPRM) soil moisture retrieval algorithm with field measurements in South Korea from March to September, 2014. Results of mean bias and root mean square error between AMSR2 LPRM soil moisture products (X-band) and ground measurements showed reasonable value of 0.03 and 0.16. Also, the maximum of the Pearson correlation coefficients was 0.67, which showed good agreement in terms of temporal variability with ground measurements. By comparing AMSR2 soil moisture with in-situ measurement according to the overpass time and band frequency, X-band products on the ascending time outperformed than those of C1-band and C2-band. Furthermore, this study offers an insight into the applicability of the AMSR2 soil moisture products for monitoring various natural disasters at a large scale such as drought and flood.
Development of minimum-salinity feedwater for reduction of unit production cost of reverse-osmosis desalination plants
Park, Namsik ; Jang, Chi Woong ; Babu, Roshina ;
Journal of Korea Water Resources Association, volume 49, issue 5, 2016, Pages 431~438
DOI : 10.3741/JKWRA.2016.49.5.431
Large energy consumption is one of the main weaknesses of RO desalination. A new method is proposed to reduce the energy consumption of RO desalination which depends on the salinity of the feedwater. Low salinity feedwater can be obtained using groundwater wells which extracts both fresh groundwater and subsurface sea water. Subsurface feedwater is advantageous in overcoming other problems associated with surface seawater intakes. Salinities of groundwater depend on a number of factors. In this work a new simulation-optimization model is proposed to identify well locations and pumping rates with would provide the required design flow rate with the minimum salinity. When groundwater is developed in a coastal area, the saltwater wedge advances inland and may contaminate existing groundwater wells, which must be prevented. The model can protect existing wells while developing minimum salinity feedwater. Examples are provided to demonstrate the usage of the model.
Regional frequency analysis using spatial data extension method : I. An empirical investigation of regional flood frequency analysis
Kim, Nam Won ; Lee, Jeong Eun ; Lee, Jeongwoo ; Jung, Yong ;
Journal of Korea Water Resources Association, volume 49, issue 5, 2016, Pages 439~450
DOI : 10.3741/JKWRA.2016.49.5.439
For the design of infrastructures controlling the flood events at ungauged basins, this study tries to find the regional flood frequencies using peak flow data generated by the spatial extension of flood records. The Chungju Dam watershed is selected to validate the possibility of regional flood frequency analysis using the spatially extended flood data. Firstly, based on the index flood method, the flood event data from the spatial extension method is evaluated for 22 mid/smaller sub-basins at the Chungju Dam watershed. The homogeneity of the Chungju dam watershed was assessed in terms of the different size of watershed conditions such as accumulated and individual sub-basins. Based on the result of homogeneity analysis, this watershed is heterogeneous with respect to individual sub-basins because of the heterogeneity of rainfall distribution. To decide the regional probability distribution, goodness-of fit measure and weighted moving averages method from flood frequency analysis were adopted. Finally, GEV distribution was selected as a representative distribution and regional quantile were estimated. This research is one step further method to estimate regional flood frequency for ungauged basins.
Regional frequency analysis using spatial data extension method : II .Flood frequency inference for ungaged watersheds
Kim, Nam Won ; Lee, Jeong Eun ; Lee, Jeongwoo ; Jung, Yong ;
Journal of Korea Water Resources Association, volume 49, issue 5, 2016, Pages 451~458
DOI : 10.3741/JKWRA.2016.49.5.451
In order to infer regional flood frequency for ungauged watersheds, index flood method was applied for this study. To pursuit this given purpose, annual peak flood data for 22 watersheds located at the upstream of the Chungju Dam watershed were obtained from the spatial extension technique. The regionalization of mean annual flood was performed from extended flood data at 22 points. Based on the theory that flood discharge and watershed size follows the power law the regionalization generated the empirical relationship. These analyses were executed for the full size of the Chungju Dam watershed as one group and three different mid-size watersheds groups. From the results, the relationship between mean annual flood and watershed sizes follow the power law. We demonstrated that it is appropriate to use the relationship between specific flood discharges from the upper and lower watersheds in terms of estimating the floods for the ungaged watersheds. Therefore, not only the procedure of regional frequency analysis but also regionalizaion analaysis using finer discretization of the regions interest with respect to the regional frequency analyisis for the ungauged watersheds is important.