• Journal of Korean Society of Environmental Engineers
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• v.37 no.9
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• pp.517-525
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• 2015

This study analyzes water quality change trends in three major rivers in Daejeon and effect of discharge from Daejeon Wastewater Treatment Plant between 1992 and 2014. As of 2014, COD concentration in the Gab-cheon-A station is in level VI for Korea river water quality standard while BOD and TP are in level III. As expansions of the treatment plant, water quality in the Gab-cheon River has been improving accordingly. However, during the study period, TN concentrations of the headwater and the most downstream locations of the Gab-cheon River have increased about twice and three times, respectively. It was estimated that the treatment plant is responsible for 35%. 46%, 76% and 63% of BOD, COD, TN and TP loadings of the Gab-cheon River, respectively. It was also estimated that small tributaries and nonpoint sources are responsible for 54% and 47% of BOD and COD loadings of the Gab-cheon River. Therefore, it is recommended to further reduce nutrient loadings from the treatment plant and also reduce surface runoff organic loading from nonpoint sources including small tributaries and storm sewers.

• Journal of Korea Water Resources Association
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• v.39 no.10 s.171
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• pp.881-890
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• 2006

Hydrological characteristics and urbanization effects in the Gap river catchment were investigated employing the SWAT model. The hydrological characteristics analysis showed that total runoff in the whole catchment from 2001 to 2004 consists of 44% of groundwater flow, 6% of lateral flow and 50% of surface flow under year 2000 landuse conditions. The analysis of urbanization effect using different landuse maps for year 1975 and 2000 indicated that although 5% increase in urbanized areas did not significantly impact on the total runoff in the whole catchment, a sub-basin where urbanized area increased by 32% over the past 30 years showed $68{\sim}73%$ decrease in groundwater flow and $22{\sim}66%$ increase in surface flow. It was found that urbanization decreased overall soil moisture and percolation rate except for some increase in soil moisture during dry season. Urbanization effect was found more sensitive during a dry year which has less rainfall and higher evapotranspiration than during a wet year. Therefore, from the results of this study we could infer increased flood damage during wet season and dried stream during dry season due to urbanization. To conclude, the results of this study can provide fundamental information to the eco-friendly restoration project for the three major rivers (Gap-cheon, Yudeung-cheon and Daejeon-cheon) in Daejeon Metropolitan City.