• 한국물환경학회지
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• 제30권2호
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• pp.148-158
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• 2014

In order to assess the effect of TMDLs management and improve that in the future, it is necessary to analyze long-term changes in water quality during management period. Therefore, long term trend analysis of BOD was performed on thirty monitoring stations in Geum River TMDL unit watersheds. Nonparametric trend analysis method was used for analysis as the water quality data are generally not in normal distribution. The monthly median values of BOD during 2004~2010 were analyzed by Seasonal Mann-Kendall test and LOWESS(LOcally WEighted Scatter plot Smoother). And the effect of Total Maximum Daily Loads(TMDLs) management on water quality changes at each unit watershed was analyzed with the result of trend analysis. The Seasonal Mann-Kendall test results showed that BOD concentrations had the downward trend at 10 unit watersheds, upward trend at 4 unit watersheds and no significant trend at 16 unit watersheds. And the LOWESS analysis showed that BOD concentration began to decrease after mid-2009 at almost all of unit watersheds having no trend in implementation plan watershed. It was estimated that TMDLs improved water quality in Geum River water system and the improvement of water quality was made mainly in implementation plan unit watershed and tributaries.

• 한국물환경학회지
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• 제30권1호
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• pp.60-67
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• 2014

In this study, four methods for calculation of continuous daily flow was suggested using short-term or partial recording station of streamflow including missing data. Using these methods, standard flows at the outlet of unit/small basins for the management of total maximum daily loads (TMDLs) in Namgang dam basin were estimated from full-period flow duration curve (FDC). Four methods of extension are described, and their properties are explored. The methods are regression (REG), regression plus noise (RPN), and maintenance of variance extension types 1 and 2 (MOVE.1, MOVE.2). In these methods, the continuous daily flow was calculated using extension equation based on correlation analysis, after conducting the correlation analysis between historic record of streamflow and long-term recording station (a base station). Finally the best optimal method was selected as the MOVE.2, and the standard flows in the abundant, ordinary, low and drought flow estimated from FDC was evaluated using MOVE.2 in unit/small basins.

• 한국물환경학회지
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• 제30권2호
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• pp.226-241
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• 2014

This study proposes schemes of GIS-based system development for integrated information management in water environment linked with Korean Reach File (KRF). For this purpose, precedent studies and systems of the U.S. were investigated and analyzed to induce optimal methodology for Korean circumstances. Thereafter, data linkage methods of KRF and Water Environment Information System (WEIS), system configuration plans, application development plans, and KRF improvement and maintenance plans were considered. For data linkage and system configuration, three methods were suggested: an overlay operation-based data linkage method, entering spatial addresses into the existing DB, and creating link information between KRF and the existing DB. The first method was predicted to be the most effective for system implementation, the second method is advantageous for search tasks, and the third method is advantageous for system security and maintenance. Various types of applications should be developed in the consideration of the types of the users and their usages. Moreover, there is a need for further research on regular renewal of KRF, standard development, expansion of construction areas, etc. Based on the present results, research on actual system design and development also should be conducted for supporting Total Maximum Daily Loads (TMDLs).

• 한국물환경학회지
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• 제24권6호
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• pp.676-681
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• 2008

The evaluation of the effluent water quality of sewage treatment plant is one of the most important factor in calculating total maximum daily loads (TMDLs). Current method to calculate 95% upper limit of effluent water quality of sewage treatment plant assuming normal distribution of data needs to be implemented in case of non-normal distribution. We have investigated the applicability of percentile ranking method as a non-parametric statistical analysis in case of non-normal distribution of data.

• 한국물환경학회지
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• 제30권2호
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• pp.128-137
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• 2014

The land use of the unit watersheds should be maintained appropriately in order to keep the load allotment stable for the management of Total Maximum Daily Loads (TMDLs). This study classified the land area in four types and analyzed the use of each land type and its changing pattern by calculating the occupation and conversion ratios for the unit watersheds in three river basins. The forest land showed the greatest occupation ratio with 63.0%, followed by the farm land with 23%, the other area with 8.0% and the site area with 6.0% in 2003. The occupation ratio of the site and the other area increased by 0.4% and 0.2% respectively, and that of the farm and the forest land decreased by 0.4% and 0.2% respectively in 2007. The conversion ratio for the site area ranged from 1.65% to 1.97%, for the farm land from -0.47% to -0.33%, for the forest land from -0.10% to -0.04% and for the other area from 0.17% to 1.97%. It can be inferred that the decrease in the farm and the forest land contributed to the increase in the site area and that the increase in the other area was mainly made by the decrease in the forest land. It could be more effective to take into account the changes in the site area and in the forest land in the process of developing the TMDL plans.

• 한국농공학회논문집
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• 제52권3호
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• pp.81-88
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• 2010

The purpose of this study is to analyze the spatial characteristics of Namgang-Dam watershed for a Total Maximum Daily Loads (TMDL). Three TMDL target sites, Gyeonghogang1, 2, Namgang-Dam2, are located within Namgang-Dam watershed. Under the current criterion for TMDLs, 3-year arithmetic mean BOD concentration of the target sites should not exceed the target concentration for 2 consecutive years. Two and three times of violation were observed for Gyenghogang2 and Namgang-Dam2 sites while no violation was found for Gyeonghogang1 site. However, no violation was found since 1999 for all three sites. Correlation between each 12 stations within the watershed were analyzed and cluster analysis was conducted to figure out the spatial characteristics of the watershed. Correlation coefficient between Gyonghogang1 and 2 was high (0.758) while the coefficients between lake station (Namgang-Dam2) and stream stations (Gyonghogang1 and 2) were very low. Dendrogram indicated that all of three Namgang-Dam stations were very close and Gyenghogang1, 2 stations were also close.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2010년도 학술발표회
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• pp.1355-1359
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• 2010

The purpose of this study is to analyze the spatial characteristics of Namgang-Dam watershed for a Total Maximum Daily Loads(TMDL). Three TMDL target sites, Gyeonghogang1, 2, Namgang-Dam2, are located within Namgang-Dam watershed. Under the current criterion for TMDLs, 3-year arithmetic mean BOD concentration of the target sites should not exceed the target concentration for 2 consecutive years. Two and three times of violation were observed for Gyenghogang2 and Namgang-Dam2 sites while no violation was found for Gyeonghogang1 site. However, no violation was found since 1999 for all three sites. Correlation between each 12 stations within the watershed were analyzed and cluster analysis was conducted to figure out the spatial characteristics of the watershed. Correlation coefficient between Gyonghogang1 and 2 was high (0.758) while the coefficients between lake station (Namgang-Dam2) and stream stations (Gyonghogang1 and 2) were very low. Dendrogram indicated that all of three Namgang-Dam stations were very close and Gyenghogang1, 2 stations were also close.

• 한국환경과학회지
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• 제26권8호
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• pp.939-953
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• 2017

For the development of flow duration curves for the management of 41 Total Maximum Daily Load (TMDL) units of the Nakdong River basin, first, an equation for estimating daily flow rates as well as the level of correlation (correlation and determination coefficients) was extrapolated through regression analysis of discrete (Ministry of Environment) and continuous (Ministry of Land, Infrastructure and Transportation) measurement data. The equation derived from the analysis was used to estimate daily flow rates in order to develop flow duration curves for each TMDL unit. By using the equation, the annual flow duration curves and flow curves, for the entire period and for each TMDL unit of the basin, were developed to be demonstrated in this research. Standard flow rates (abundant-, ordinary-, low- and drought flows) for major flow duration periods were calculated based on the annual flow duration curves. Then, the flow rates, based on percentile ranks of exceedance probabilities (5, 25, 50, 75, and 95%), were calculated according to the flow duration curves for the entire period and are suggested in this research. These results can be used for feasibility assessment of the set values of primary and secondary standard flow rates for each river system, which are derived from complicated models. In addition, they will also be useful for the process of implementing TMDL management, including evaluation of the target level of water purity based on load duration curves.

• 한국물환경학회지
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• 제29권3호
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• pp.400-408
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• 2013

Total phosphorus was set as a target indicator to prevent eutrophication and algae growth, etc., in three major rivers (Nakdong River, Geum River and Yeongsang/Seomjin River) for the second phase (2011 ~ 2015) in total maximum daily loads (TMDLs) system. However, total phosphorus management was restrictively introduced, i.e., upstream of the Lake Daechung, in the Geum River watershed. Total phosphorus concentration and trophic levels in downstream of the Lake Daechung (include Mangyeong and Dongjin rivers) were increased more than upstream. Therefore, it is necessary to expand total phosphorus management in all watersheds of the Geum River. If total phosphorus was managed in all area of the Geum River watershed, it is possible to decrease total phosphorus concentration and trophic levels, and solve the unbalanced water quality between up and downstream of the Lake Daechung.

• 한국물환경학회지
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• 제31권6호
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• pp.732-738
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• 2015

Water quality in four major river basin in Korea was managed with Total Maximum Daily Load (TMDL) System. The unit watershed in TMDL system has been evaluated with Target Water Quality (TWQ) assessment using average water quality, without considering its volume of water quantity. As results, although unit watershed are obtained its TWQ, its allocated loads were not satisfied and vice versa. To solve these problems, a number of TWQ assessments with using Load Duration Curve (LDC) have been studied at other watersheds. The purpose of this study was to evaluate achievement of TWQ with Flow Duration Curve (FDC) and Load Duration Curve(LDC) at 26 unit watersheds in Han river basin. The results showed that achievement rates in TWQ assessment with current method and with LDC were 50~56 % and 69~73%, respectively. Because of increasing about 20% of achievement rates with using LDC, the number of exceeded unit watershed at Han river Basin was decreased about 4~6 unit watersheds.