• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.4
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• pp.19-26
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• 2010

To provide the basic information for the water quality management of the Sumjin River Basin, delivery ratios for flow duration were studied. Using the day-interval data set of discharge and water quality observed from the Chooryeong-cheon watershed, the flow-duration and discharge-load relation curves for the watershed were established, then the load-duration curve was constructed. Delivery ratios for flow duration were also developed. Delivery ratios showed wide variation according to flow conditions. In general, delivery ratio of high flow condition showed higher value reflecting nonpoint source pollution contribution from the forest dominating watershed. To resolve this problem, a regression model explaining the relation between flow rate and delivery ratio was suggested. The delivery ratios for different flow regime could be used for pollutant load estimation and TMDL (Total maximum daily load) development.

• Environmental Engineering Research
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• v.15 no.2
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• pp.117-121
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• 2010

The continual extraction and indiscriminante use of groundwater for residential sectors could cause a decrease in the groundwater level in Para$\tilde{n}$aque river and Las Para$\tilde{n}$aque City; and allows saltwater to penetrate into the aquifer due to the proximity of Manila Bay. This study models the present condition and extent of saltwater intrusion in the aquifer bounded by Para$\tilde{n}$aque river River and Manila Bay. The model is simulated using a 3D finite element modeling software (FEMWATER) that is capable of modeling the groundwater flow condition in the aquifer. Moreover, the model can also be used to predict the future condition of the aquifer for better groundwater management. This study aims to raise public awareness of the extent of the problem and the possible side effects incurred. The model will serve as a basis for further studies on remediation techniques and saltwater intrusion control in the coastal aquifer of Para$\tilde{n}$aque river City.

• Journal of Korean Society on Water Environment
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• v.35 no.6
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• pp.497-509
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• 2019

After the Total Maximum Daily Loads(TMDLs) was applied, it became beyond the limit of concentration management. However, it does not adequately reflect the characteristics of various watersheds, and causes problems with local governments because of the standard flow set. Thus, in this study, the Han River system is organized into four groups in estimating the Pollution Contribution by applying the Flow Duration Curve(FDC) created by the daily flow of data from the HSPF. And the method of this study is expected to be valuable as basic data for the TMDLs. As a result, Group I contains the main watersheds with no large hydraulic structures and tributary watersheds. There is no specificity in the FDC and the Pollution Contribution is estimated as rainfall runoff. Group II contains watersheds near the city where the FDC is maintained above a certain level during the Low Flow Conditions and the Pollution Contribution is estimated as the discharge flow of large scale point pollution facilities. Group III contains the main watersheds in which the large hydraulic structures are installed and FDC is curved in the Low Flow Conditions. So the Pollution Contribution is estimated as the water quality of the large hydraulic structures. Group IV contains the upstream in mainstream watersheds in which the large hydraulic structures are installed and the FDC is disabled before the Low Flow Conditions. As the flow is concentrated in the High Flow Conditions, the non-point pollution sources are estimated as the Pollution Contribution.

• Journal of Korea Water Resources Association
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• v.45 no.10
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• pp.969-981
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• 2012

In this study, we analysed hydrologic variability in quantity and onset of annual maximum flow and low flow by impacts of the different phases of ENSO (El Ni$\tilde{n}$o Southern Oscillation) over the Han River Basin. The results show that annual maximum flow has increased statistically significant about 48.3% of all over the watershed. The onset of annual maximum flow was delayed in the west of the Han River basins and in the east of the basins was likely to be rapid onset. Also, this study shows that 7-day low flow was deceased statistically significant about 26.0% of the total area in the Han River Basin, and onset of 7-day low flow tends to be faster in the upper-middle basins of the Han River. The onset of annual maximum flow shows similar pattern during the CT (Cold tongue)/WP (Warm-pool) El Ni$\tilde{n}$o years, but annual maximum flow appeared less in 89.0% of all basins during the CT El Ni$\tilde{n}$o years. In addition, the onset of 7-day low flow tended to be faster about 17 days on average during the WP El Ni$\tilde{n}$o years, and 72.7% of the basins show significant increase during the CT El Ni$\tilde{n}$o years. Consequently, it was found that the different phases of CT/WP El Ni$\tilde{n}$o have effects on sensitivity to variability in quantity and onset of water resources over the Han River Basin. We expect that the present diagnostic study on hydrological variability during different phases of ENSO will provide useful information for long-term prediction and water resources management.

• Journal of Korean Society on Water Environment
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• v.37 no.1
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• pp.32-46
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• 2021

South Korea has been divided into quantities and water quality, and due to a revision of the Government Organization law in June 2018, the controversial water management system was integrated into the Ministry of Environment. The total Maximum Daily Loads System has been called the flower of water quality control, and since 2004, all three major river systems which have been introduced into the Han River system, despite its various difficult environments, and subsequently leading to all of the four major rivers undergoing obligatory implementation since 2013. Currently, the target TMDL (Han River Phase 1 and Other Water Systems Phase 3) for the 2020 stage has been implemented. The domestic TMDL established a basic plan for calculating the load which complies with the unit watershed's target water quality, as well as an implementation plan for annual load management, both which have been institutionalized in order to evaluate load compliance on a repeated annual basis. Local governments ask external organizations to conduct investigations every year in order to assess the transition, which thereby requires tens of millions of won every year. Therefore, an assessment and management model that can be easily operated at the TMDL personnel level is required. In this study, when the Han river Water System TMDL was implemented in earnest, we confirmed the the water quality improvement effect when TMDL was introduced to major inflow tributaries (TancheonA, JungnangA, AnyangA) under the Seoul City's jurisdiction through the use of the total amount control unit basin evaluation technique. By presenting customized management measures, we propose the guidelines that are necessary for determining more effective water environmental policies.

• Water Engineering Research
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• v.6 no.3
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• pp.123-130
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• 2005

A good understanding of the interaction between flow, vegetation, and sediment is required for successful river restoration and sustainable flood management. The purpose of this paper is to provide a summary of available methods to determine flow resistance of natural rivers with vegetation, and discuss the influence of vegetation on erosion and sedimentation processes. Recently, significant advances have been made, but the effects of vegetation on flow and sediment dynamics are still not fully understood. Possible solutions to close the gaps in the current knowledge are suggested, with special focus directed to the determination of the interactive width between main channel and vegetated floodplains, the flow resistance of flexible vegetation with and without leaves, and the flow over submerged vegetation with low water depth.

• Journal of Korea Water Resources Association
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• v.37 no.7
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• pp.517-526
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• 2004

Agricultural water plays an important role in the national water management. Irrigation return flow is the amount of irrigated water that returns to the river system. In the water resources development planing and management, an accurate estimation of the irrigation return flow is very important. In this study, a 5.5 ha small size paddy area in Kyungbuk province is selected and the water balance components are measured during the 2003 growing season. The total irrigation return flow ratio was 53.7%, of which 30.2% was rapid return flow and 23.5% was delayed return flow.

• Journal of Korea Water Resources Association
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• v.45 no.11
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• pp.1157-1168
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• 2012

In this study, we assess changes in water quality trends over time based on certain control measurements in order to identify and analyze the cause of the trend in water quality. The current water pollution in the Nakdong River was analyzed, as it suggests that the significant changes in water quality have occurred in between 2006 and 2010. Based on monthly average data, we have examined for trends of the Nakdong River watershed in water temperature, Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Nitrogen (TN), and Total Phosphorus (TP). Moreover, we have investigated seasonal variation of water quality of sites within the Nakdong River Basin by implementing further analyses such as, Correlation Coefficient, Regression Analysis, Hierarchical Clustering Method, and Time Series Analysis on SPSS. Geology and topography of the watershed, controlled by various conditions such as, climate, vegetation, topography, soil, and rain medium, have been affected by the non-homogeneity. Our study suggests that such variables could possibly cause eutrophication problems in the river. One possible way to overcome this particular problem is to lay up a ship on the river by increasing the nasal flow measurement of the Nakdong River during rainy season. Moreover, the water management requires arranging the measurement of the flow in order to secure the river while the numerous construction projects need to be continuously observed. However, the water is not flowing tributary of the reason for the timing to be flowing in a natural state of river water and industrial water intake because agriculture. Therefore, ongoing research is needed in addition to configuration of all observations.

• Journal of Environmental Science International
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• v.26 no.4
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• pp.433-445
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• 2017

In recent years, the United States has used the Load Duration Curve (LDC) method to identify water pollution problems, considering the size of the pollutant load in the entire stream flow condition to effectively evaluate Total Maximum Daily Loads (TMDLs). A study on the improvement of the target water quality evaluation method was carried out by comparing evaluations of two consecutive years of water quality and LDC data for 41 unit watersheds (14 main streams and 27 tributaries). As a result, the achievement rate of the target water quality evaluation method, according to current regulations, was 68-93%, and that by the LDC method was 82-93%. Evaluating the target water quality using the LDC method results in a reduction in the administrative burden and the total amount of planning as compared to the current method.

• Journal of Wetlands Research
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• v.24 no.1
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• pp.44-51
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• 2022

In this study, TOPSIS(Techniques for Order Performance by Similarity to Ieal Solution) was used to evaluate the installation points of water quality monitoring networks in 34 streams of the Nakdong River watershed. The Nakdong River System has been measuring water quality and flow in 195 local streams since 2011. In particular, the 34 key management points are areas with many pollutants and poor water quality, requiring continuous water quality management. For the selection of points requiring management, 10 indicators were selected for evaluation, and the selected indicators were standardized and weighted using the entropy method. As a result of weight calculation, the presence or absence of a nearby measuring network received the greatest weight, and the average water quality and presence of an industrial complex obtained the highest weight. The evaluated data are judged to be the research results necessary for the establishment of a new water quality measurement network in the Nakdong River system and continuous water quality management in tributaries.