• Journal of Environmental Impact Assessment
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• v.29 no.1
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• pp.61-77
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• 2020

In South Korea, major public waters have been systematic management under national level. Water environment network has been continuous monitoring for change of aquatic ecosystem, river and reservoir. In Water Quality Monitoring Networks, the data have been generally monitored Per eight days or month, while in Automatic Water Quality Monitoring Network the data have been monitored at daily intervals. Therefore, we were compared and analyzed water quality data between the networks using statistic method for same water quality item. Mann-kendall test results confirm that all points in Water Temperature (WT) and DO were not statistically significant. In particular, the result revealed that there is significant variation of TOC in the four different sites, TN in two different sites, TP in three different sites, WT in seven different sites, pH in two different sites between Water Quality Monitoring Network and Automatic Water Quality Monitoring Network. As a result firm LOWESS, TOC and pH clearly shows different trend. Among different sites, the water quality show the significantly positive correlations between at Sinam-Sangju2 and Namgang-Namgang4. Negative correlation significantly appeared in TP (ADD_Lower-AD1 site), TOC (DG-SG site), pH (GR-GR site), TP (JP-CN) and TN, TP, pH, EC, DO (GC-GC2-1 site).

• Journal of Korean Society on Water Environment
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• v.33 no.1
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• pp.51-62
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• 2017

The purpose of this study is to evaluate on the applicability of Load Duration Curve (LDC) method using Maintenance of Variance Extension types 2 method and sampling data for efficient total maximum daily loads at the Nakbon-A unit watershed in Korea. The LDC method allows for characterizing water quality data such as BOD, TOC, T-N and T-P in this study at different flow regimes(or quarters). BOD usually exceeded the standard value (exceedance probability 50%) at low flow zone. On the other hand, TOC, T-N, T-P usually exceeded the standard value at dry and low flow zone. Seasonally all water quality variables usually exceeded the standard value at Q1(Jan-Mar) and Q2(Apr-Jun) zones. Improvement of effluent control from wastewater treatment plants are effective to improve BOD and T-P.

• Journal of Environmental Impact Assessment
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• v.27 no.4
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• pp.353-366
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• 2018

The purpose of this study was assessment the quality of water by using the statistical analysis technique of the Water flow and water quality from January 2012 to December 2016 at the unit basin for total pollutant load management system (TPLMS) in the Imjin River. Water flow and water quality were monitored at an average of 8 day intervals, 11 parameters were used for correlation analysis, principal component analysis (PCA), factor analysis (FA), and cluster analysis (CA). The Hierarchical CA was classified into three according to the change of space, such as natural rivers, urban rivers, point with large influence of point pollution source, it was found that the type of contamination source the similarity of water quality affected the classification of cluster. Using one-way analysis of variance (ANOVA) and post-hoc Analysis, there were statistically significant differences between mean values among the clusters. Correlation analysis showed the correlation coefficient between $COD_{Mn}$ and TOC was 0.951 (p<0.01) and the correlation was statistically significantly higher. According to the result PCA and FA, 3 principal components can explaining 72% of the total variations in water quality characteristics and main factor was EC, $BOD_5$, $COD_{Mn}$, TN, TP and TOC indirect indicators of organic matter and nutrients were influenced. This study presented the regression equation obtained by applying the factor scores to the multiple linear regression analysis and concluded that the management Indirect indicators of organic matter and nutrients is important for water quality management in the Imjin River basin.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.830-840
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• 2011

Climate change has been settled as pending issues to consider water resources and environment all over the world, however, scientific and quantitative assessment methods of climate change have never been standardized. When South Korea headed toward water deficiency nation, the study is not only required analysis of atmospheric or hydrologic factors, but also demanded analysis of correlation with water quality environment factors to gain management policies about climate change. Therefore, this study explored appropriate monthly rainfall elasticity in chosen 41 unit watersheds in Nak-dong river which is the biggest river in Korea and applied monitored discharge data in 2004 to 2009 with monthly rainfall using Thiessen method. Each unit watershed drew elasticity between water temperature and water quality factors such as BOD, COD, SS, T-N, and T-P. Moreover, this study performed non-linear correlation analysis with monitored discharge data. Based on results of analysis, this is first steps of climate change analysis using long-term monitoring to develop basic data by Nak-dong river Environmental Research Center (Ministry of Environment) and to draw quantitative results for reliable forecasting. Secondary, the results considered characteristic of air temperature and rainfall in each unit watershed so that the study has significance its various statistical applications. Finally, this study stands for developing comparable data through "The 4 major river restoration" project by Korea government before and after which cause water quality and water environment changes.

• Journal of Soil and Groundwater Environment
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• v.17 no.3
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• pp.10-20
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• 2012

The pumping capacity of riverbank filtration using radial collector wells at the Geum, Yeongsan, Seomjin, and Nakdong rivers was evaluated using Milojevic's equation. Assessment of the radial collector wells' pumping capacity in riverbank filtration was carried out using a case study in which one set of collector wells is installed in the watershed of each river. Nakdong River was evaluated to have the highest pumping capacity for riverbank filtration. The areas capable of producing over 10,000 $m^3$ per day were found mostly in the Nakdong River.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.620-627
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• 2007

In this study a general analysis method for watersheds with the entire runoff conditions and corresponding water quality is proposed and its applicability based on the currently available information is investigated. Using the 8-day-interval data set of runoff and water quality observed by Nakdong River Environment Research Center, the flow duration curve and discharge-load relation curve for each unit watershed are established, then the load duration curve is finally constructed. This paper discusses how the load duration curve can be used in the assessment of TMDL. The entire Nakdong river watershed is also divided into prior managing areas of point sources or non-point sources in a way of general management. It is thought that LDC can be a great tool for visualizing overall probabilities of current water quality and thus for the TMDL management.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.5
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• pp.417-429
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• 2013

The current study attempted to assess the environmental value of Geum-river estuary for rational management decision-making. To investigate the comprehensive properties of the Geum-river estuary, we applied the contingent valuation method based on multi-attribute utility theory. We surveyed a randomly selected sample of 400 and 600 households of the Geum-river estuary-neighboring area (Jeollabuk-do, Chungcheongnam-do), and other nation-wide large districts (except Jeollabuk-do, Chungcheongnam-do, and Jeju-do), respectively, and carried out person-to-person interviews with subjects on their willingness-to-pay for the estuary conservation and management program. Respondents, overall, accepted the contingent market system and were willing to contribute a significant amount, that is 1,497 won for the residents from the Geum-river estuary-neighboring area and 4,343 won for the residents from other nation-wide large districts on average, per household per year. These results implied that there were large difference between the two groups. The aggregate values of the Geum-river estuary for the estuary-neighboring area and other nation-wide large districts amount to 2.13 and 70.15 billion won, respectively, per year. This quantitative value deduced from the current study, could be a useful baseline fact for any decision-making process particularly in the establishment of management policies for the Geum-river estuary.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.50-50
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• 2018

As the frequency of drought due to climate change is increasing and the severity of drought becomes severe, it is urgent to prepare measures against extreme drought. Despite the significant impacts of drought on the coupled human-environment system, we have not fully understood the consequences of extreme droughts affecting all parts of the environment and our communities, and there is no system to assess environmental droughts quantitatively. Even if a drought disaster occurs on the same scale, the severity of the drought depends on the vulnerability of the region. Therefore, this study proposes environmental drought assessment based on water quality vulnerability to extreme drought for the resilient proactive response.

• Journal of Environmental Impact Assessment
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• v.26 no.6
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• pp.418-430
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• 2017

The quality of surface water is a very important issue to use various demands like as drinking water, industrial, agricultural and recreational usages. There has been an increasing demand for monitoring water quality of many rivers by regular measurements of various water quality variables. However precise and effective monitoring is not enough, if the acquired dataset is not analyzed thoroughly. Therefore, the aim of this study was to estimate differences of seasonal and regional water quality using multivariate data analysis for each investing tributaries in Han River. Statistical analysis was applied to the data concerning 11 mainly parameters (flow, water temperature, pH, EC, DO, BOD, COD, SS, TN, TP and TOC) for the time period 2012~2016 from 12 sampling sites. The seasonal water quality variations showed that each of BOD, TN, TP and TOC average concentration in spring and winter was higher than that of summer and fall, respectively. In summer each flow rate and average concentration of SS was higher than any other seasons, respectively. The correlation analysis were explained that EC had a strong relationship with BOD (r=0.857), COD (r=0.854), TN (r=0.899) and TOC (r=0.910). According to principal component analysis, five principal components (Eigenvalue > 1) are controlled 98.0% of variations in water quality. The first component included TP, DO, pH. The second component included EC, TN. The third component included SS. The fourth component included flow. The last component included Temp. Cluster analysis classified that spring is similar to fall and winter with water quality parameters. AnyA, WangsA, JungrA and TancA were identified as affected by organic pollution. Cluster analysis derived seasonal differences with investigating sites and better explained the principal component analysis results.

• Journal of Korea Water Resources Association
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• v.47 no.3
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• pp.269-283
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• 2014

This study evaluated the environmental impact based on watershed characteristics and climate change using RCP climate change scenarios provided by the Korea Meteorological Administration. Future dam inflow was estimated by the SWAT model. Dam safety evaluation and downstream duration curve analysis was performed using HEC-ResSim model. Trends of water quality was analyzed through seasonal-Kendall Test using existing water quality observation data. Release discharge and tributary runoff derived SWAT and HEC-ResSim models applied to Qual2E and the future change in water quality trends were analyzed. Integrated environmental review watershed following techniques will be able to obtain the river environment management system and environmental issues such as climate change, new guidelines for preemptively response will be provided.