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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 48, Issue 12 - Dec 2015
Volume 48, Issue 11 - Nov 2015
Volume 48, Issue 10 - Oct 2015
Volume 48, Issue 9 - Sep 2015
Volume 48, Issue 8 - Aug 2015
Volume 48, Issue 7 - Jul 2015
Volume 48, Issue 6 - Jun 2015
Volume 48, Issue 5 - May 2015
Volume 48, Issue 4 - Apr 2015
Volume 48, Issue 3 - Mar 2015
Volume 48, Issue 2 - Feb 2015
Volume 48, Issue 1 - Jan 2015
Selecting the target year
Drought Frequency Analysis Using Hidden Markov Chain Model and Bivariate Copula Function
Chun, Si-Young ; Kim, Yong-Tak ; Kwon, Hyun-Han ;
Journal of Korea Water Resources Association, volume 48, issue 12, 2015, Pages 969~979
DOI : 10.3741/JKWRA.2015.48.12.969
This study applied a probabilistic-based hidden Markov model (HMM) to better characterize drought patterns. In addition, a copula-based bivariate drought frequency analysis was employed to further investigate return periods of the current drought condition in year 2015. The obtained results revealed that western Kangwon area was generally more vulnerable to drought risk than eastern Kangwon area using the 40-year data. Imjin-river watershed including Cheorwon area was the most vulnerable area in terms of severe drought events. Four stations in Han-river watershed showed a joint return period exceeding 1,000 years associated with the drought duration and severity in 2014-2015. Especially, current drought status in Northern Han-river and Imjin-river watershed is most severe drought exceeding 100-year return period.
A Study on the Predictive Power Improvement of Time Series Model with Empirical Mode Decomposition Method
Kim, Taereem ; Shin, Hongjoon ; Nam, Woosung ; Heo, Jun-Haeng ;
Journal of Korea Water Resources Association, volume 48, issue 12, 2015, Pages 981~993
DOI : 10.3741/JKWRA.2015.48.12.981
The analysis of hydrologic time series data is crucial for the effective management of water resources. Therefore, it has been widely used for the long-term forecasting of hydrologic variables. In tradition, time series analysis has been used to predict a time series without considering exogenous variables. However, many studies using decomposition have been widely carried out with the assumption that one data series could be mixed with several frequent factors. In this study, the empirical mode decomposition method was performed for decomposing a hydrologic time series data into several components, and each component was applied to the time series models, autoregressive moving average (ARMA). After constructing the time series models, the forecasting values are added to compare the results with traditional time series model. Finally, the forecasted estimates from ARMA model with empirical mode decomposition method showed better performance than sole traditional ARMA model indicated from comparing the root mean square errors of the two methods.
Development of Radar Tracking Technique for the Short -Term Rainfall Field Forecasting-
Kim, Tae-Jeong ; Lee, Dong-Ryul ; Kwon, Hyun-Han ;
Journal of Korea Water Resources Association, volume 48, issue 12, 2015, Pages 995~1009
DOI : 10.3741/JKWRA.2015.48.12.995
Weather radar rainfall data has been recognized for making valuable contributions to short-term flood forecasting and management over the past decades. There are several advantages to better monitoring rainfall in ungauged area compared to ground-based rain gauges with which spatial patterns of the rainfall are not effectively identified. Hence, this study aims to develop a new scheme to forecast spatio-temporal rainfall field. The proposed model was based on an advection scheme to track wind patterns and velocity. The results showd a promising forecasting skill with quantitative and qualitative measures. It was confirmed that the forecasted rainfall may be effectively used an input data for a distributed hydrological model.
Quantitative Characterization of Historical Drought Events in Korea - Focusing on Drought Frequency Analysis in the Five Major Basins -
Lee, Joo-Heon ; Jang, Ho-Won ; Kim, Jong-Suk ; Kim, Tae-Woong ;
Journal of Korea Water Resources Association, volume 48, issue 12, 2015, Pages 1011~1021
DOI : 10.3741/JKWRA.2015.48.12.1011
This study aims to investigate droughts from the magnitude perspective based on the SPI (Standardized Precipitation Index) and the theory of runs applicable to quantitative analysis of drought in South Korea. In addition, the dry spell analysis was conducted on the drought history in the five major river basins of South Korea to obtain the magnitude, duration and severity of drought, and the quantitative evaluation has been made on historical droughts by estimating the return period using the SDF (Severity-Duration-Frequency) curve gained through drought frequency analysis. The analysis results showed that the return periods for droughts at the regional and major river basin scales were clearly identified. The return periods of severe drought that occurred around the major river basins in South Korea turn out to be mostly 30 to 50 years with the years of the worst drought in terms of severity being 1988 and 1994. In particular, South Korea experienced extremely severe droughts for two consecutive years during the period between 1994 and 1995. Drought in 2014 occurred in the Han River basin and was evaluated as the worst one in terms of severity and magnitude.
Numerical Simulation on Seawater Intrusion in Coastal Aquifer using N-S Solver Based on Porous Body Model
Lee, Woo-Dong ; Jeong, Yeong-Han ; Hur, Dong-Soo ;
Journal of Korea Water Resources Association, volume 48, issue 12, 2015, Pages 1023~1035
DOI : 10.3741/JKWRA.2015.48.12.1023
This study applies 3-D N-S solver based on PBM (Porous Body Model), LED-WASS-3D ver 2.0 to directly analyze non-linear interaction of seawater-freshwater-coastal aquifer in order to simulate the seawater infiltration into coastal aquifer. This numerical simulation is the first trial in Korea, as well as unusual and new numerical analysis abroad. Firstly, to validate the applied numerical model, the validity and effectiveness was verified for the numerical model by comparing and considering it with the result of laboratory experiment for seawater-freshwater interface in coastal aquifer. And then it simulated the seawater infiltration into coastal aquifer considering the changed levels of seawater and groundwater in order to analyze the distribution characteristics of flow field and seawater-freshwater interface of coastal aquifer as the level difference between seawater and groundwater and rate of seawater level (
) increased. In addition, the characteristics of seawater infiltration were analyzed from the vertical salinity in the coastal aquifer by
, which cannot be obtained from existing non-diffusion numerical models. Finally, it analyzed the effect of
on the seawater infiltration distance in coastal aquifer, which was indexed.
An Assessment of Flooding Risk Using Flash Flood Index in North Korea - Focus on Imjin Basin -
Kwak, Chang Jae ; Choi, Woo Jung ; Cho, Jae Woong ;
Journal of Korea Water Resources Association, volume 48, issue 12, 2015, Pages 1037~1049
DOI : 10.3741/JKWRA.2015.48.12.1037
The most of natural disasters that occur in North Korea are flood, typhoon and damage from heavy rain. The damage caused by those disasters since the mid-1990s is aggravating North Korea's economic difficulties every year. By recognizing the seriousness of the damages from the floods, the North Korean government has carried out the river maintenance, farmland restoration, land readjustment and afforestation projects since the last-1990s, but it has failed preventing the damages. In order to estimate the degree of flood risk regarding damage from chronic floods that occur inveterately in North Korea, this research conducted an additional simulation for rainfall-runoff analysis to reflect the characteristics of the ungauged area that make foreign countries hard to obtain the hydrological data and do not open the topographical data to public. In addition, this research estimates the degree of flood risk by selecting the factors of the hazard, exposure and vulnerability by following the standards of the Intergovernmental Panel on Climate Change (IPCC).
Determination of Optimal Hourly Water Intake Amount for H Arisu Purification Center using Linear Programming
Lee, Chulsoo ; Lee, Kangwon ;
Journal of Korea Water Resources Association, volume 48, issue 12, 2015, Pages 1051~1064
DOI : 10.3741/JKWRA.2015.48.12.1051
Currently, the H purification plant determines the hourly water intake amount based on operator experience and skill. Therefore, inevitably, there are deviations among operators. While meeting time-varying demand and maintaining the proper water level in the clean water reservoir, the methodology for minimizing electricity cost, when dealing with different electricity rate time zones, is a very complicated problem, which is beyond an operator's capability. To solve this problem, a linear programming (LP) model is proposed, which can determine the optimal hourly water intake amount for minimizing the daily electricity cost. It is shown that an inaccurate estimate for the hourly water usage in the demand areas causes the water level constraint to be violated, which is the weak point of the proposed LP method. However, several examples with real-field data show that we can practically and safely solve this problem with safety margins. It is also shown that the safety margin method still works effectively whether the estimate is accurate or not. The operators need not attend the site at all times under the proposed LP method, and we can additionally expect reductions in labor costs.
Analysis of Flood Control Effect by Applying the Connecting Channel in Estuary Area Including the Confluence of Two Rivers
Kim, Sooyoung ; Kim, Hyung-Jun ; Yoon, Kwang Seok ;
Journal of Korea Water Resources Association, volume 48, issue 12, 2015, Pages 1065~1075
DOI : 10.3741/JKWRA.2015.48.12.1065
In the estuary where the structure such as river-mouth weir has been installed, the flow is developed very complicatedly due to river water from upstream, tide of the sea and floodgate operation. Especially, if basin outlets more than one exists in one estuary, the boundary conditions will be significantly more complex form. Saemangeum(SMG) project area in Korea is the most typical example. There are Mankyung river and Dongjin river in upstream. The water of them inflows into SMG project area. In the downstream, river flow was drained from inland to sea over the SMG sea dike through the sluice. The connecting channel was located between Mankyung and Dongjin basins. It functions not only as transportation by ship in ordinary period but also as flood sharing by sending flood flow to each other in flood period. Therefore, in order to secure the safety against flood, it is very important to understand the flood sharing capacity for connecting channel. In this study, the flood control effect was analyzed using numerical simulation. Delft3D was used to numerical simulation and simulated period was set up with neap tide, in which the maximum flood stage occurred due to poor drainage. Actually, three connecting channels were designed in land use plan of the SMG Master Plan, but they were simplified to a single channel for conciseness of analysis in this study. According to the results of numerical analysis, the water level difference between two basins was increased and the maximum flood stage at dike sluice was also upraised depending on decrease of conveyance. And the velocity induced by same water level difference was decreased when the conveyance became smaller. In certain conveyance above, there was almost no flood control effect. Therefore, if the results of this study are considered for design of connecting channel, it will be expected to draw the optimal conveyance for minimizing dredging construction cost while maximizing the flood control effect.
A Study on Stability of Levee Revetment in Meandering Channel
Kim, Sooyoung ; Yoon, Kwang Seok ; Kim, Hyung-Jun ;
Journal of Korea Water Resources Association, volume 48, issue 12, 2015, Pages 1077~1087
DOI : 10.3741/JKWRA.2015.48.12.1077
The levee protect lifes, houses, and properties by blocking overflow of river. The revetment is forced to be covered on the slope of levee in order to prevent erosion. The stability of revetment is very important enough to directly connected to the stability of levee. In this study, the weak points of revetment on meandering channel were found by movable revetment experiment and the velocity and the water surface elevation (WSE) were measured at main points. The 3-D numerical simulations were performed under same conditions with experiment. And unclear flow characteristics by the limit of measuring instruments were analyzed through numerical simulation. Consequently, the section of large wall shear stress and the failure section are almost the same. Despite of small wall shear stress, the revetments located at right bank were carried away because of circulation zone due to secondary flow by meandering. With existing riprap design formula, the sizes of riprap determined using maximum local velocity were 1.5~4.7 times greater than them using mean velocity. As a result of this study, it is necessary to calculate the size of riprap in other ways for meandering and straight channel. At a later study, if the weighted value considered the radius of curvature and shape of hydraulic structure is applied to riprap design formula, it is expected that the size of revetment was evaluated rationally and accurately.