• Journal of Korean Society on Water Environment
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• v.28 no.3
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• pp.409-417
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• 2012

SWAT model was applied for the Nakdong River Basin to characterize water quality variability and assess the feasibility of using the load duration curve to water quality management. The basin was divided into 67 sub-basins considering various watershed environment, and rainfall runoff and pollutant loading were simulated based on 6 year measurements of meteo-hydrological data, discharge data of treatment plants, and water quality data (SS, T-N and T-P). The results demonstrate that non-point source loads during wet season increase by 80 ~ 95% of total loads. Although the rate of water flow governs the amount of SS that is transported to the main streams, nutrient concentrations are highly elevated during dry season by being concentrated. This phenomenon is more pronounced in the lower basin, receiving large amounts of urban point source discharges such as treated sewages. Also, the load duration curves (LDC) demonstrate dominant source problems based on the load exceedances, showing that SS concentrations are associated with the rainy season and nutrients, such as T-P, may be more concentrated at low flow and more diluted at higher flow. Overall, the LDC method could be used conveniently to assess watershed characteristics and pollutant loads in watershed scale.

• Journal of Korea Water Resources Association
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• v.54 no.3
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• pp.191-201
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• 2021

Rivers have been damaged due to rapid urbanization, and river management has been carried out focusing on flow and flood control functions. Recently, interest in river restoration, emphasizing the environmental aspects of rivers, is increasing, but the beginning of river restoration requires an appropriate evaluation of the environmental flow required for the ecosystem. This study analyzed the effects on the habitat of the river ecosystem by estimating the changes in flow regime and environmental flow following the construction of the Buhang dam in Gamcheon, the first tributary of the Nakdong River. To evaluate the environmental flow, the dominant species of Gamcheon, Zacco Platypus, and the protected species Squalidus gracilis majime, and riparian vegetation were selected, and the environmental flow was calculated using the HEC-EFM (Ecosystem Function Model). The evaluated environmental flow was linked with hydraulic analysis and GIS platform, and habitat area change and habitat connectivity analysis before and after dam construction were performed by spatial habitat analysis in the river. Based on the results of this study, it can be used as a river restoration project and a dam operation plan considering the river environment through the calculation of environmental flow and habitat connectivity analysis to improve the habitat of the river ecosystem.

• Journal of Korean Society on Water Environment
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• v.29 no.4
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• pp.514-522
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• 2013

The major 24 tributaries in Nam-River mid-watershed were monitored for discharge and water quality in order to understand the characteristics of the watershed and to select the tributary catchment for improving water quality. According to the analytical results of discharge and water quality monitoring data of 24 tributaries, the mean value of discharge below $0.1m^3/s$ was 62.5% among the monitored tributaries and it mostly exceeded the water quality standards of Nam-river mid-watershed ($BOD_5$ = 3 mg/L, T-P = 0.1 mg/L over). According to the stream grouping method and the water quality delivery load density ($kg/day/km^2$) based on the results of tributary discharge and water quality monitoring, the tributary watersheds for improving the water quality were selected. In the Nam-River mid-watershed, tributaries in the GaJwaCheon, HaChonCheon catchment (Group D, $BOD_5$ = 3 mg/L over) and in the UirYeongCheon, SeokGyoCheon catchment (Group A, T-P = 0.1 mg/L over), which have a small flow (and/or large flow) and a high concentrations of water pollutants. The various water quality improving scheme for tributaries, in accordance with the reduction of potential point source pollution by living sewage and livestock wastewater, should be established and implemented.

• Journal of Korea Water Resources Association
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• v.49 no.8
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• pp.673-683
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• 2016

An Idea to estimate flexible criteria for river water use permits was proposed that takes the spatio-temporal flow variation along the river into account, which was applied to the Keumho River, one of the tributary of the Nakdong River in Korea. This idea implies the temporal division of four periods with different criteria, combining flood/non-flood seasons and irrigation/non-irrigation periods, while a single one has been applied throughout the year in the current practice. Through flow regime analysis of daily natural flow simulations at Dongchon and Seongseo, the control points of the study area, Q355 and 1Q10 for non-flood and non-irrigation period, Q275 for non-flood and irrigation period, Q185 for flood and irrigation period were suggested respectively. So, those values that subtract instream flow were determined as the flexible criteria in each season. From the comparison of current practice and the proposed method, it was estimated that $10.6\;million\;m^3/year$ is available for more water use permits without additional development of water storage. Therefore, it is conceived that flexible criteria for river water use permission suggested in this study can contribute to improve the national policies for more efficient water resources management in the future.

• Journal of the Korean Society of Industry Convergence
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• v.8 no.4
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• pp.213-220
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• 2005

The Youngwal 1, Youngwal 2 and Youngchun gaging stations are observed flood flow and low flow during Mar. 2004~Oct. 2004. They are observed water stages and flow velocities for flood and low flow. The observed data are used to derived rating curve and equations. The HEC-RAS model is applied for hydraulic modeling in gauging stations. The model is designed to perform one-dimensional hydraulic calculations for an river improvement plan in a full network of natural and constructed channels, and is comprised of a graphical user interface(GUI), separate hydraulic analysis components, data storage and management capabilities, graphics and reporting facilities.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.78-78
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• 2020

The Se San and Srepok river basins (2S) are the two major tributaries of the Mekong River, both of which originate in the territory of Viet Nam and flow to Cambodia to meet at Stung treng with the Sekong river (originating in Lao PDR) to form the 3S river basin before joining the Mekong mainstream. In the territory of Viet Nam, the 2S river basins are located in the Central Highlands including 5 provinces, arranged by geographical location from north to south namely Kon Tum, Gia Lai, Dak Lak, Dak Nong and Lam Dong. This is a region with a very important strategic position in terms of economy, politics and defense for the whole country with many potential advantages for economic development. However, the limited and vulnerable basin water resources are under the pressure of socio-economic development in line with increasing water demands for various sectors. In order to overcome the water management challenges, a long-term water resources planning has conducted to support the 2S River Basin Committee (RBC) in effective planning and operation as part of the WB Mekong-Integrated Water Resources Management (IWRM) Project. This paper introduces the outline and progress of the river basin planning using analytical DSS toolkits to analyze, evaluate and formulate the planning options.

• KCID journal
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• v.7 no.1
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• pp.57-68
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• 2000

• Journal of Korean Society of Water and Wastewater
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• v.11 no.3
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• pp.87-95
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• 1997

A river water quality management model was made by Dynamic programming. This model optimizes the wastewater treatment cost of the application area, and computed water quality with it must meet the water quality standard. And this model takes into consideration tributary input, wastewater treatment plant effluent, withdrawls for several purposes. Modified Streeter-Phelps equation was used to calculate BOD and DO. Optimization problem was solved with particular exceedance probability flow, and the water quality of each point was calculated with the decided treatment efficiencies. At that time, the probability satisfying the water quality standard of constraints to the exceedance probability of the flow. The developed model was applied to the lower part of the Han-River. The reliability to meet the water quality standard is 70 % when 4 wastewater treatment plants of Seoul City are operated by activated sludge system at autumn of the year 2001. Treatment cost of this case is 121.288 billion won per year.

• Journal of Environmental Science International
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• v.27 no.12
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• pp.1179-1193
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• 2018

The purpose of this study at water quality pollutants to propose proper management method for the Osu-A unit watershed which is the influent tributary located upstream of the Sumjin -river among the 13 unit watersheds in the Sumjin-river water system. Analyzed the correlation between flow-pollution loading and the correlation between land use type, BOD and TP items, and analyzed 8-day intervals Cumulative Flow Duration Curve (CFDC) and Load Duration Curve (LDC) to evaluate water quality damage. As a result, both BOD and TP were larger than 1 and the concentration of water pollutants increased with increasing flow. BOD was positively correlated with Urban and Field, and TP was positively correlated with Field with 0.710. As a result of the LDC, BOD was analyzed that the target water quality was achieved with the excess rate of less than 50%, and TP exceeded the target water quality by 50.1%. BOD usually exceeded the standard value (exceedance probability 50%) at low flow zone and On the other hand, TP usually exceeded the standard value at high flow zone. Monthly BOD (April to June) and TP (May to August) exceeded the standard. Sewage Wastewater treatment and non-point pollution control is Osu-A unit watersheds are effective in improving BOD and TP.

• Journal of Korean Society of Disaster and Security
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• v.12 no.2
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• pp.35-45
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• 2019

The enlargement and reduction of river channels can not only change the flow of water but also alter sedimentation patterns, thus hindering smooth flood conveyance. Accordingly, this study aims to analyze the effects of the sudden enlargement of river channels on changes in the riverbed and river flow. For this purpose, as part of the "Hometown River" Construction Project, this study examined the local river Kyungpo-cheon, which a section of the river channel was widened by at least two- to three-fold, using RMA-2 and SED-2D models to simulate the changes in flow characteristics and riverbed variation due to the widening of the channel. The results of the study indicated that widening the Kyungpo -cheon river channel secured its dimensional stability in comparison to before widening. however, due to a flood frequency of more than once per year, future maintenance and management will be costly and time-consuming.