• Journal of Korean Society on Water Environment
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• v.33 no.5
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• pp.525-530
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• 2017

The attainment ratios of the water quality goals of the 114 mid-watershed representative stations, examined during the period2011 to 2015, were evaluated in the study. Of the four major river basins, the attainment ratio on water quality goal of the Geum River basin turned out to be the lowest. As a result of formal evaluation of the attainment ratios of BOD, COD and TOC, it was found that the attainment ratio of COD was much lower than that of BOD and TOC (I a circumstance thought to be caused by the higher COD/BOD and COD/TOC ratios of the water quality of the river than those of the environmental water quality standard). As well, higher COD/BOD and COD/TOC of wastewater discharged from point and non-point sources (other than those of the environmental water quality standards) might possibly represent one of the reasons. We also compared attainment ratio between the main stream and tributaries, which indicated that the higher attainment ratio was present in the main stream. The attainment ratio is also documented as more significant in the winter season than the summer season, possibly due to the contribution of non-point pollutants swept in by rain during the summer season during documented periods of high precipitation. Thus, water quality management in summer season and improvement of water quality of the tributaries might be important as a means of increasing attainment ratio on water quality goal.

• Journal of the Korean Geographical Society
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• v.32 no.4
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• pp.445-462
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• 1997

This study was conducted to analyze the spatial and temporal characteristics of stream water quality and to charify the management of watershed environment from the standpoint of hydrological geography. To achieve the purpose of the study, the Wangsook River was chosen. As the result of this study, the specific conclusions were drawn. 1. In general, WT(water temperature) of the downstream is higher than that of the upstream. The value of winter WT measured in densely populated area is higher than that measured under the natural conditions. The seasonal variation of WT at upstream sites is greater than that of downstream. 2. Rhe water quality of main channel is dependent on that of tributaries. Especially, the values of pH, EC, TDS in main channel depend upon those of tributaries. Among the tributaries of the Wangsook river, the Jingun-chon and Yongam-chon have mostly influence on the water quality of the main channel. 3. Generally, the values of COD measured in the Wangsook River are over the 5th Grade considering from a point of water quality standards of inland lake. However, BOD, phosphorus and nitrogen concentrations have to be measured to clear the water quality conditions of the river. 4. The regional people who live in the catchment of Wangsook river have different perception about the water pollution of the river. The regional people lacks in the understanding of the Wangsook river cause a bad influence upon the hydrological management of watershed environment.

• Journal of Korean Society on Water Environment
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• v.23 no.6
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• pp.814-821
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• 2007

This study was estimated water quality to raw water quality management of the Maeri intake station in the Nakdong River using Multivariate Analysis. The results of Principle Component Analysis was explained up to 76.9% of total water quality by three principle components. The 1st, 2nd was explained 44.7%, 17.9% and third was explained 14.3%. Also, the three factors was derived from Factor Analysis. The 1st factor was estimated as the matabolism and organic matter pattern related to algal growth. The 2nd factor was judged as the pollution of pattern related to the discharge from stream of the Nakdong River and 3rd factor was viewed as the hydrological variation pattern related to particle matter. The results of Cluster Analysis were classified into three groups.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.1
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• pp.15-22
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• 2009

This study reports the serial use of a 3-D hydrodynamic model, EFDC-Hydro and a dynamic water quality model WASP7.2 that are maintained by USEPA. The 48 km section of the Geum River downstream between Daechung Dam and Gongju was selected as a sample study site. Topographical information was used to accurately represent morphology of the study site and boundary conditions were derived from governmental databases including WAMIS by Ministry of Land and Ocean and WEIS by Ministry of Environment. EFDC-Hydro was successfully calibrated for observed water level and WASP was calibrated using monthly observed water quality data obtained from the above sources. It was found that the current water quality target of BOD for the Geum River-H point could not be met on monthly basis though every other tributary of the area would meet its own water quality target as assigned in Korean TMDL. This study proposed the new target BOD water quality for the Gabcheon and Mihocheon as 4.3 and 3.6 mg/l, respectively so that the Geum River-H point can meet the target. When Sejong City is constructed, it is estimated that effluent discharge limit of BOD must be less than 4.5 mg/l to meet water quality of the point. This study shows that it is possible to carry out more precise modeling considering both water movement and water kinetics by using EFDC and WASP simultaneously.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.2
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• pp.40-49
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• 1997

From water management point of view, the industrialization that we have achieved in the last decades brought out two major changes: water shortage and water quality deterioration. They are getting the big obstacles we must overcome to continuously pursue industrialization for further development in the next century. Many plans using dams and advanced treatment methods have been developed for control of quantity and quality, respectively. In this paper, an alternative is conceptually reviewed which is much different from the plans in regard that the alternative looks at system itself. It is based on an interceptor system coupling with a concept of zero-discharge. This system allows no discharge of wastewaters from point-sources to waterbodies which are very sensitive in terms of water quality. In addition reuse of treated effluents is emphasized to a maximum extent. The application of the system to the Nak-Dong river basin indicated that an interceptor system will need from the middle reaches of the basin where industrialization gets heavier. Since wastewaters are not directly discharged to the river, water quality of the down stream will improve. Treated effluents will be able to be reused at a number of industrial complex which currently get water from the Nak-Dong river. This reuse will help alleviate water shortage. The biggest problem anticipated is cost for building and operating such system. A cost-sharing plan among the beneficiaries is considered. Further research is suggested focusing on detailed engineering and technical matters for potential implementation.

• Journal of Korean Society on Water Environment
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• v.33 no.2
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• pp.219-229
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• 2017

A watershed-river linked modeling system was developed to forecast the water quality, particularly weekly changes in chlorophyll-a concentration, of the Yeongsan River, Korea. Hydrological Simulation Program-Fortran (HSPF) and Environmental Fluid Dynamics Code (EFDC) were adopted as the basic model framework. In this study, the EFDC model was modified to effectively simulate the operational condition and flow of multi-functional weirs constructed in the main channel of rivers. The model was tested against hydrologic, water quality and algal data collected at the right upstream sites of two weirs in 2014. The mean absolute errors (MAEs) of the model calibration on the annual variations of river stage, TN, TP, and algal concentration are 0.03 ~ 0.10 m, 0.65 ~ 0.67 mg/L, 0.03 ~ 0.04 mg/L, and $9.7{\sim}10.8mg/m^3$, respectively. On the other hand, the MAE values of forecasting results for chlorophyll-a level at the same sites in 2015 range from 18.7 to $22.4mg/m^3$, which are higher than those of model calibration. The increased errors in forecasting are mainly attributed to the higher uncertainties of weather forecasting data compared to the observed data used in model calibration.

• Journal of Korea Water Resources Association
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• v.33 no.2
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• pp.145-157
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• 2000

The Water Quality Analysis Simulation Program 5 (WASP5) and HEC-2 models have been coupled and applied to find the possibility of simulation of long-term river water quality variation. The EUTR05 as a simulator of water quality simulation in WASPS model was used to simulate the water quality variables in the downstream of Geum-River from Daechung multi-purpose dam during the dry period. The water quality and flow rate conditions have been measured at the stage measurement stations located in the downstream of Geum-River from Daechung dam in December, 1998 and January and March, 1999. The water quality simulation model was calibrated with January data of 1999, and verified with December data of 1998 and March data of 1999. The trend of longitudinal variation of water quality variables simulated by model is consistent with that of measured water quality constituents except chlorophyll-a, $BOD_5,\;NH_3-N\;and\;PO_4-P$ simulated with March data of 1999. Furthennore, the chlorophyll a concentration in the mainstream of Geum-River was simulated by changing the concentrations of $PO_4-P$ and/or $NH_4-N$ flowing into the mainstream of Geum-River from Gabcheon and Mihocheon. The variation of chlorophyll a concentration in the mainstream was almost ignorable except only when $NH_3-N\;and\;PO_4-P$ concentrations decreased by 70% flow into the mainstream from Gabcheon and Mihocheon.

• Journal of Environmental Health Sciences
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• v.27 no.2
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• pp.119-126
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• 2001

The key point in establishing water quality management measures is how to decide the load reduction for pollution sources. This study was performed to compare reduction methods for BOD loadings to achieve water quality standards at the end of the Yeongsan river. The target year is 2006 and 2011 and reduction methods are uniform treatment and treatment by influence rate. Using QUAL2E model, the study was performed under the conditions of establishing and non-establishing the publicly owned treatment works(POTWs). Uniform treatment which allocate the same reduction rate to pollution sources showed that all streams into the river should be applied for the reduction. However, treatment by influence rate which allocate the reduction rate by the order of influence rate showed that achieving target quality might be possible with a few streams for the reduction. But total amount of load reduction of streams was not significantly different from two methods.

• Journal of Korean Society on Water Environment
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• v.31 no.6
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• pp.723-731
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• 2015

We investigated the spatial and temporal patterns of water quality in the Gangjung-Goryoung weir that is located in the middle area of the Nakdong river, Korea. The monitoring results indicated that there are discernible vertical differences in water quality during the pre- and post-monsoon periods (May to September). During this period, it was observed that the weak thermal stratification formed at the maximum level, and pH, Chl-a, and DO concentrations in the surface layer were higher than those in the bottom layer. This vertical difference was especially noticeable for DO concentrations: there were DO depletions at the bottom layer in late June to early August. During the summer monsoon period with heavy rainfall, there was a decline in vertical differences in water quality. From this study, it was suggested that continuous monitoring of vertical profiles could become a useful tool for identifying the spatial and temporal distributions of water quality and for developing the best management policy for water quality in the Nakdong river.

• The Korean Journal of Ecology
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• v.24 no.4
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• pp.253-258
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• 2001

Land use pattern in the Wangsuk river watershed was investigated on the bases of physiognomic vegetation maps made from the aerial photograph interpretation and field check. Landscape structure was analyzed using a GIS program supported by ArcView. Landscape structure depended on the geographical position of the river, such as the upper, middle and lower river. Watersheds of the upper and middle rivers were dominated by forests composed of secondary forest and plantation. But agricultural fields dominated that of the middle and lower river. Urban area and agricultural fields increased in from the upper toward the lower river watersheds. In addition to, a transformation of agricultural pattern into an institutional agriculture was characteristic in the middle and lower river basins. Water qualities of the Wangsuk river were usually better in the order of the upper, middle, and lower river, but they were fluctuated according to the site. Such fluctuation would due to self-purification of the river and land use pattern of the watershed as the non-point source. In this viewpoint, a strategy to manage the water quality in the level of watershed is urgently required.