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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 46, Issue 12 - Dec 2013
Volume 46, Issue 11 - Nov 2013
Volume 46, Issue 10 - Oct 2013
Volume 46, Issue 9 - Sep 2013
Volume 46, Issue 8 - Aug 2013
Volume 46, Issue 7 - Jul 2013
Volume 46, Issue 6 - Jun 2013
Volume 46, Issue 5 - May 2013
Volume 46, Issue 4 - Apr 2013
Volume 46, Issue 3 - Mar 2013
Volume 46, Issue 2 - Feb 2013
Volume 46, Issue 1 - Jan 2013
Selecting the target year
Effect of Climate Change on Fish Habitat in the Nakdong River Watershed
Kang, Hyeongsik ; Park, Min-Young ; Jang, Jae-Ho ;
Journal of Korea Water Resources Association, volume 46, issue 1, 2013, Pages 1~12
DOI : 10.3741/JKWRA.2013.46.1.1
In this study, the potential effects of increased water temperature on fish habitat were analysed in the streams of Nakdong River watershed. The changes in suitable habitats for each fish species and in species number at a habitat site were predicted, based on the maximum thermal tolerances of 22 fish species. The estimated maximum thermal tolerance ranged between
. Then, the increase of water temperature in 78-sites of Nakdong River watershed by 2100 was predicted by using the estimated air temperature data by 2100 in the literature and the regression analysis between air-temperature and water-temperature at each sites. The water temperature was estimated to have increased by
in 2011~2040 (period S1), 2041~2070 (S2), and 2071~2100 (S3), respectively. With such increases in water temperature, the averaged suitable habitats for all 22 fish species would be influenced by 21.9%, 36.3%, and 51.4% in periods S1, S2, and S3, respectively.
A Development of Regional Frequency Model Based on Hierarchical Bayesian Model
Kwon, Hyun-Han ; Kim, Jin-Young ; Kim, Oon-Ki ; Lee, Jeong-Ju ;
Journal of Korea Water Resources Association, volume 46, issue 1, 2013, Pages 13~24
DOI : 10.3741/JKWRA.2013.46.1.13
The main objective of this study was to develop a new regional frequency analysis model based on hierarchical Bayesian model that allows us to better estimate and quantify model parameters as well as their associated uncertainties. A Monte-carlo experiment procedure has been set up to verify the proposed regional frequency analysis. It was found that the proposed hierarchical Bayesian model based regional frequency analysis outperformed the existing L-moment based regional frequency analysis in terms of reducing biases associated with the model parameters. Especially, the bias is remarkably decreased with increasing return period. The proposed model was applied to six weather stations in Jeollabuk-do, and compared with the existing L-moment approach. This study also provided shrinkage process of the model parameters that is a typical behavior in hierarchical Bayes models. The results of case study show that the proposed model has the potential to obtain reliable estimates of the parameters and quantitatively provide their uncertainties.
Dynamic Characteristics of Multiple Bars in the Channels with Erodible Banks
Jang, Chang-Lae ;
Journal of Korea Water Resources Association, volume 46, issue 1, 2013, Pages 25~34
DOI : 10.3741/JKWRA.2013.46.1.25
In this study, the development processes of multiple bars in the channels with erodible banks were investigated by double Fourier analysis. The initially straight channels in the experiment flume were widened with eroding the side banks, and the multiple bars were generated and grew due to stalling of the sediment on the bed. The bars migrated downstream and the size of the bars increased with time. The flow was separated around the bars, and the bed and banks near the bars were scoured due to the impinged secondary flow. The morphologic changes were accelerated by the bank erosion, which affected the fluctuations of sediment discharge downstream. The double Fourier analysis of the bed waves showed that 1-1 mode (alternate bar) was dominant at the initial stage of the channel development. As time increased, 2-3 mode (central or multiple bars) was dominant due to the increased width to depth ratio. Moreover, the number of bars in a cross section of the channel were increased due to the non linearity of alternate bars. The width to depth ratio was increased by the bank erosion, which affected the bar migration and the bar wavelength. However, the dimensionless tractive force was decreased by it.
Estimation of Flood Risk Index for the Nakdong River Watershed
Song, Jae Ha ; Kim, Sangdan ; Park, Moo Jong ; Choi, Hyun Il ;
Journal of Korea Water Resources Association, volume 46, issue 1, 2013, Pages 35~45
DOI : 10.3741/JKWRA.2013.46.1.35
The aim of study is to present how to estimate and use the FRI (Flood Risk Index) for classifying area zones based on regional flooding risk in terms of the integrated flood risk management. To estimate the FRI at a spatial resolution of city/county/town units for the Nakdong River Watershed, the 17 representative flood indexing factors are carefully selected for the three flood indexes, such as PI (Pressure Index), SI (State Index), and RI (Response Index) under the P-S-R (Pressure-State-Response) classification system. Because flood indexing factors are measured at different scales and units, they are transformed into a common domain by the T-Score normalization technique. The entropy weight coefficient method is also applied to calculate the weight of flood indexing factors in order to reduce subjective judgement on the effect of weight coefficients. The three flood indexes of PI, SI, and RI are integrated for an overall value of the FRI to evaluate the flood risk of districts. To examine the practical application of the proposed FRI, the FRI results with/without the weight coefficients are compared with flooding zones of natural disaster risk areas officially announced in 2010. It is expected that the FRI ensured by full verification can make regional protection plans against flooding disasters with respect to causes and characteristics of past floods.
Development of a New Flood Index for Local Flood Severity Predictions
Jo, Deok Jun ; Son, In Ook ; Choi, Hyun Il ;
Journal of Korea Water Resources Association, volume 46, issue 1, 2013, Pages 47~58
DOI : 10.3741/JKWRA.2013.46.1.47
Recently, an increase in the occurrence of sudden local flooding of great volume and short duration due to global climate changes has occasioned the significant danger and loss of life and property in Korea as well as most parts of the world. Such a local flood that usually occurs as the result of intense rainfall over small regions rises quite quickly with little or no advance warning time to prevent flood damage. To prevent the local flood damage, it is important to quickly predict the flood severity for flood events exceeding a threshold discharge that may cause the flood damage for inland areas. The aim of this study is to develop the NFI (New Flood Index) measuring the severity of floods in small ungauged catchments for use in local flood predictions by the regression analysis between the NFI and rainfall patterns. Flood runoff hydrographs are generated from a rainfall-runoff model using the annual maximum rainfall series of long-term observations for the two study catchments. The flood events above a threshold assumed as the 2-year return period discharge are targeted to estimate the NFI obtained by the geometric mean of the three relative severity factors, such as the flood magnitude ratio, the rising curve gradient, and the flooding duration time. The regression results show that the 3-hour maximum rainfall depths have the highest relationships with the NFI. It is expected that the best-fit regression equation between the NFI and rainfall characteristics can provide the basic database of the preliminary information for predicting the local flood severity in small ungauged catchments.
Derivation of Flood Frequency Curve with Uncertainty of Rainfall and Rainfall-Runoff Model
Kwon, Hyun-Han ; Kim, Jang-Gyeong ; Park, Sae-Hoon ;
Journal of Korea Water Resources Association, volume 46, issue 1, 2013, Pages 59~71
DOI : 10.3741/JKWRA.2013.46.1.59
The lack of sufficient flood data being kept across Korea has made it difficult to assess reliable estimates of the design flood while relatively sufficient rainfall data are available. In this regard, a rainfall simulation based derivation technique of flood frequency curve has been proposed in some of studies. The main issues in deriving the flood frequency curve is to develop the rainfall simulation model that is able to effectively reproduce extreme rainfall. Also the rainfall-runoff modeling that can convey uncertainties associated with model parameters needs to be developed. This study proposes a systematic approach to fully consider rainfallrunoff related uncertainties by coupling a piecewise Kernel-Pareto based multisite daily rainfall generation model and Bayesian HEC-1 model. The proposed model was applied to generate runoff ensemble at Daechung Dam watershed, and the flood frequency curve was successfully derived. It was confirmed that the proposed model is very promising in estimating design floods given a rigorous comparison with existing approaches.
Modification of the Fixed Coefficient Method for the Parameter Estimation of Storage Function Method
Chung, Gunhui ; Park, Hee-Seong ;
Journal of Korea Water Resources Association, volume 46, issue 1, 2013, Pages 73~85
DOI : 10.3741/JKWRA.2013.46.1.73
The researches on the parameter estimation for storage function method have been conducted for a long time using different methods. However, the determination of the optimal parameters takes a long time and there is a controversy that the proposed optimal parameters do not likely represent the physical characteristics of watershed. In this study, the characteristics of the continuity and storage function equation was analyzed and sensitivities were evaluated. As the result, the only optimal solution is suggested among several local optimums. It is also shown that the lag time is able to be determined using the direct runoff starting time of the watershed. From the sensitivity analysis, it is also proved that the determination of the lag time is very important and the only optimal solution could be found easily after selecting the lag time. Therefore, unlike the traditional optimization method, the proposed method does not take a long time to find the optimal solution which is depending on the characteristics of the rainfall events. The fixed coefficient method which is a method to estimate the optimal parameters of storage function method has been modified using the proposed method. Therefore, the practical efficiency to apply storage function method could be enhanced by applying the proposed method. While the traditional method takes care only the error of the runoff hydrograph, it is very important that the proposed method considers the characteristics of the watershed.
Long-Term Simulation of Reservoir Sedimentation Considering Particle-Size Distributions of Suspended Sediment and Bed Materials
Kim, Dae Geun ; Shin, Kwang Gyun ;
Journal of Korea Water Resources Association, volume 46, issue 1, 2013, Pages 87~97
DOI : 10.3741/JKWRA.2013.46.1.87
The bed change model of HEC-RAS was used to predict the formation of a delta upon an influx of high-density sediment while taking the particle-size distributions of the suspended sediment and bed materials into account. The model was able to reasonably predict both the spatial-temporal distribution of the delta and the amount of deposited sediment according to the grain size. In addition, it was able to estimate the main type of grains that sediment at particular locations at particular times moderately well. It is expected that the simulation and the analysis considering these particle-size distributions of sediment will provide important information on planning and maintenance of the water resource related facilities.