• Journal of Korea Water Resources Association
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• v.51 no.7
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• pp.617-627
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• 2018

In this study, CMIP5 GCMs rainfall data (2011~2099) based on RCP scenarios were used to analyze the extreme drought evaluation for the future period. For prospective drought assessment, historical observations were used based on the Automated Surface Observing System (ASOS) data (1976~2010) of the Korea Meteorological Administration. Through the analysis of various indicators, such as average annual rainfall, rainy days, drought spell, and average drought severity was carried out for the drought evaluation of the five major river basins (Han river, Nakdong river, Geum river, Sumjin river, and Youngsan river) over the Korean peninsula. The GCMs that predicted the most severe future droughts are CMCC-CMS, IPSL-CM5A-LR and IPSL-CM5A-MR. Moderate future droughts were predicted from HadGEM2-CC, CMCC-CM and HadGEM2-ES. GCMs with relatively weak future drought forecasts were selected as CESM1-CAM5, MIROC-ESM-CHEM and CanESM2. The results of this study might be used as a fundamental data to choose a reasonable climate change scenario in future extreme drought evaluation.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.1
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• pp.1-8
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• 2005

We estimated the loadings of nitrogen and phosphorus flowing into Gwangyang Bay front river for monthly interval from April to December of 2003. We analyzed the concentrations of nitrogen and phosphorus in water and estimated the flowing rates of fresh water in 34 rivers. The amounts of water flowing into the Gwdngyang Bay from Sum-Jin River was 51-76％ in the total inflow of the river. The river water over 96％ of discharge was from Sumjin River, Dong River, Ju-Kyo River, Seo River and Shinkyum River. The flowing patterns of nitrogen and phosphorus into Gwangyang Bay were similar to the flowing of river. The nitrogen and phosphorus loadings into the Bay were higher in July and August than in dry seasons. In particular, the concentrations of phosphorus were high in Namshu River, Deukyang River and Kilho River sewage during in dry seasons. The range of DIN and TN loadings from Sumjim River were 46-66％ and 36-64％, respectively. The loading of DIP and TP from Sumjim River were 2-55％ and 12-67％, respectively. These results show that the most efficient control of N. p flow into Gwangyang Bay is to restrain the inflows of N, p from Namshu River, Deukyang River and Kilho River and to restrain the flows of N, p from Dong River, Ju-Kyo River and industrial plant. The DIN/DIP atom ratio in river water was about 18 in July and August, while the ratio was more higher in dry seasons than July and August of rainy seasons. The TN/TP atom ratio in river water was about 7 in rainy seasons, while the ratios were higher than 100 in the other months of dry seasons.

• Journal of the Korean Society of Groundwater Environment
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• v.7 no.2
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• pp.66-72
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• 2000

The purpose of this study is establish a recession curve for low flow discharge in the Ssangchi basin. For this study, we selected 34 recession segments and calculated recession constants and initial discharges. The average initial discharge is 0.40 ㎥/sec and the recession constant is 0.86. With using the initial discharge and the recession constant, We got the non-linear recession cure equation. This non-linear equation is more reasonable fit than the linear equation of the recession curve for low flow.

• Korean Journal of Environmental Agriculture
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• v.19 no.5
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• pp.370-374
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• 2000

At this study, the monitoring network of water quality was established in the agricultural watershed an area 14,960 ha of the central southwest of Korea. Loads of nitrogen and phosphorus by agricultural land use were quantified bases on total amounts of stream flow. The land were used as a lowland paddy, an upland and a forest about 12.14 % (1,815 ha), 5.17 % (773 ha) and 80.31 % (12,015 ha) of the area, respectively. For six months, from May 1 to October 31, 1999, the total precipitation was 970 mm and the total amount of stream flow was $80,281,000\;m^3$. In the load of agricultural non-point sources relevant to land use, total-N was 138,413 kg, then ammonia-N 13,362 kg, nitrate-N 124,629 kg, and total-P 157 kg. The loss of nutrient which from application of chemical fertilizer were 38.0% in nitrogen and 0.1% in phosphorus to input chemical fertilizer in the watershed.

• Water Engineering Research
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• v.1 no.3
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• pp.223-231
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• 2000

The purpose of this study is the development of a system for estimating non-point sources pollutant loads from a watershed, which enables users to get insights of pollutant load distribution in the watershed during rain as well. Based on the Geographic Information System, this non-point source pollutant loading estimation system(NSPLES) consists of three distinct models such as a distributed rainfall-runoff model, a soil loss and delivery model, and a non-point source pollutant model. It also includes GIS modules for preprocessing the input data for the models and graphical postprocessing of the model outputs. The system output aren't only the hydrograph, sedimentograph, and pollutograph at the watershed outlet, but also various maps that show the distribution of soil loss over the watershed. The developed system was applied to the two upper stream areas of Sumjin river basin, Ssangchi and Gwanchon basins, and three rainfall events for respective subbasins during 1992 and 1998 were selected for the system application. The results of this showed relatively higher corelation between observed data and simulated data, and proved the applicability of the system.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.546-551
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• 2005

This study was carried out to investigate characteristics of concentration of pollutants from paddy fields district with pumping station in Sumjin river basin. The size of paddy fields was 8.06 ha and the fields were irrigated from Nae-wol and Jum-chon pumping station. Total rainfall were 1,206.5 mm from June to December in 2004, and 922.0 mm from January to August in 2005. Total irrigation and drainage water were 1014.5 mm and 968.8 mm in 2004, 655.6 mm and 687.7 mm in 2005, respectively. The measured values of T-N of the irrigation water were ranged from 0.35 mg/L to 7.26 mg/L(average : 2.09 mg/L) and T-P were ranged 0.0486 mg/L to 0.4308 mg/L (average : 0.1583 mg/L). The values of T-N of drainage water were ranged from 0.30 mg/L to 20.31 mg/L(average : 2.99 mg/L) and T-P were ranged 0.1653 mg/L to 0.8847 mg/L (average : 0.3829 mg/L).

• Journal of Environmental Impact Assessment
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• v.24 no.5
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• pp.407-419
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• 2015

The unit load of paddy field was estimated by several methods and compared in this study. Four year field study was conducted at the paddy fields located in Yeongsan river and Sumjin river basins. The unit load was estimated by four methods; (1) averaging field monitored load; (2) NIER (National Institute of Environmental Research) method which use EMC(Event Mean Concentration) and runoff ratio of rainfall groups with rainfall weighting factors; (3)method using EMC determined by best fit probability distribution; (4)method using arithmetic mean EMC and runoff ratio. The result of this study showed that the unit loads of water quality constituents by field monitoring was similar to those of NIER method whereas those by probability distribution(log-normal, gamma) method were less than unit loads of NIER method. The unit loads by arithmetic mean EMC and runoff ratio were larger than those by NIER method. The unit load by NIER method showed higher BOD, COD, SS, lesser T-N, and similar T-P values when compared to unit loads determined by MOE in 1995.

• Korean Journal of Ecology and Environment
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• v.39 no.3 s.117
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• pp.296-309
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• 2006

This study aimed to analyze water quality (temperature, secchi depth, DO, $NH_4$, $NO_3$, $PO_4$, TN, TP, chlorophyll a) and trophic state index during the period of year 2000 ${\sim}$ 2004 in Lake Juam, Lake Dongbok and Lake Youngsan. Lakes Juam and Dongbok except Lake Youngsan were stratified during warm seasons. Water turbidity estimated by secchi disk depth was the highest in Lake Youngsan compared with other lakes. DO concentrations were low in the bottom water when chlorophyll a was high in Lake Juam and Dongbok. Nutrient concentrations were higher in Lake Youngsan than other lakes whereas chlorophyll a was highest in Lake Dongbok. Lake Youngsan was the most eutrophic compared to other two lakes based on the Trophic State Idex (TP) and TSI (SD), The TSI (CHL) was high but the TSI (TP) were low in Lake Juam and Dongbok. These results suggest phytoplankton may be limited by phosphates (P) in Lake Juam and Dongbok whereas light availability in the water column may affect growth of phytoplankton in Lake Youngsan.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.549-556
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• 2017

Rivers continuously transport terrestrial organic carbon matter to the estuary and the ocean, and they play a critical role in productivity and biodiversity in the marine ecosystem as well as the global carbon cycle. The amount of terrestrial organic carbon transporting from the rivers to ocean is an essential piece of information, not only for the marine ecosystem management but also the carbon budget within catchment. However, this phenomenon is still not well understood. Most large rivers in Korea have a well-established national monitoring system of the river flow and the TOC (Total Organic Carbon) concentration from the mountain to the river mouth, which are fundamental for estimating the amount of the TOC flux. We estimated the flux of the total terrestrial organic carbon of five large rivers which flow out to the Yellow Sea, using the data of the national monitoring system (the monthly mean TOC concentration and the monthly runoff of river flow). We quantified the annual TOC flux of the five rivers, showing their results in the following order: the Han River ($18.0{\times}10^9gC\;yr^{-1}$)>>Geum River ($5.9{\times}10^9gC\;yr^{-1}$)>Yeongsan River ($2.6{\times}10^9gC\;yr^{-1}$)>Sumjin River ($2.0{\times}10^9gC\;yr^{-1}$)>>Tamjin River ($0.2{\times}10^9gC\;yr^{-1}$). The amount of the Han River, which is the highest in the Korean rivers, corresponds to be 4% of the annual total TOC flux of in the Yellow River, and moreover, to be 0.6% of Yangtze River.

• Korean Journal of Ecology and Environment
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• v.52 no.3
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• pp.221-230
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• 2019

Barbel steed (Hemibarbus labeo) is a small freshwater fish species as semi-bottom dwellers distributed in eastern Asia. We carried out characterization of the cytochrome c oxidase subunit I (COI) gene from the mitochondrial DNA of H. labeo in the Sumjin River to identify the phylogenetic location of H. labeo in the genus Hemibarbus and Cyprinidae. Multiple alignment of the 577 bp COI sequence revealed high sequence homology (99~100%) between Seomjin River H. labeo. The nucleotide sequence similarity between H. labeo (HD1) and H. mylodon was 88.91% and that of H. longirostis was 88.81% among the three species found in Korea. In addition, the nucleotide sequence similarities of H. maculatus, H. meditus, H. umbrifer and H. barbus showed 98.97%, 97.20%, 96.87% and 98.85%, respectively. Phylogenetic analysis on seven species of the genus Hemibarbus showed that the H. labeo collected in this study formed two clades. One of which consisted of Hadong, Imsil, Kangjin. The other one formed a step with HD2, HD8 and HD9 of Hadong and the H. labeo reported in Busan, Asan and Seoul, Korea. Phylogenetic position of the H. labeo among Cyprinidae showed 0.143 for the evolutionary distance from Zacco platypus and 0.006 for the H. maculatus. In addition, the genetic position of the H. labeo among 28 species of Cyprinidae was found to be located in Group I, including Gobioninae fishes. The results of this study will provide key genetic information for the taxonomic comparison in Cyprinidae and study of model fish for pollution monitoring in freshwater environments.