• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.1
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• pp.39-54
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• 2005

Seasonal variation in species composition of fish in the Geum River estuary was determined using monthly samples collected with a bag net from February to December 2003. Of a total of seventy-three species collected, four groups of fishes were distinguished. Estuarine fishes such as Chelon haematocheilus and Synechogobius hasta were collected almost all the seasons and predominated in abundance during cold months. Coastal fish species such as Sardinella zunasi, Konosirus punctatus, Engraulis japonicus, Johnius grypotus and Thryssa kammalensis were dominated from late spring to autumn. Their adults entered into the estuary in spring and a large number of their juveniles were collected in summer and autumn till moving out to deeper waters for over-wintering. A few freshwater fishes were collected when the freshwater was discharged during the rainy season. Anguilla japonica elvers (diadromous fish) and Coilia nasus (amphidromous fish) were collected in spring during their upstream migration. The principal component analysis revealed that the seasonal variation in species composition of fishes was principally determined by water temperature and/or water temperature related factors.

• Journal of Soil and Groundwater Environment
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• v.26 no.6
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• pp.186-195
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• 2021

In Korea, groundwater quality is monitored through National Groundwater Quality Monitoring Network (NGQMN) administered by Ministry of Environment. For a given contaminant, compliance to groundwater quality standards is assessed on a annual basis by monitoring the number of incidents that concentration exceeds the regulatory limit. However, this approach provides only a fractional information about groundwater quality degradation, and more crucial information such as location and severity of the contamination cannot be obtained. For better groundwater quality management on a watershed, a more spatially informative and intuitive method is required. This study presents two statistical methods to convert point-wise monitoring data into information on groundwater quality status of a watershed by using a proposed grading scale. The proposed grading system is based on readily available reference standards that classify the water quality into 4 grades. The methods were evaluated with NO₃^-, Cl^-, and total coliform data in Geum River basin. The analyses revealed that groundwater in most watersheds of Geum River basin is good for domestic or/and drinking with no treatment. But, there was notable quality degradation in Bunam seawall and So-oak downstream standard watersheds contaminated by NO₃^- and Cl^-, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.6
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• pp.850-857
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• 2022

Seventy-five Vibrio parahaemolyticus isolates from the surface seawater of the Geum River Estuary area, on the west coast of Korea, were analyzed for the presence of virulence genes and susceptibility to 17 different antimicrobials. All 75 isolates were examined for the presence of two virulence genes (tdh or trh) using polymerase chain reaction; Only one of the isolates possessed the tdh or trh gene. According to the results of disk diffusion susceptibility tests, all of the strains were resistant to penicillin G, 92.0% were resistant to ampicillin, 82.7% were resistant to amoxicillin, 2.7% were resistant to ciprofloxacin, 2.7% were resistant to trimethoprim, 1.3% were resistant to cephalothin, and 1.3% were resistant to erythromycin. However, all of the strains were susceptible to amikacin, cefoxitin, chloramphenicol, gentamycin, kanamycin, nalidixic acid, nitrofurantoin, rifampin, streptomycin, and tetracycline. The average minimum inhibitory concentrations for ampicillin for V. parahaemolyticus was 557.6 ㎍/mL. These results not only provide novel insight into the necessity for seawater sanitation in Geum river estuary area, but they help reduce the risk of contamination of antimicrobial-resistant bacteria.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.6
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• pp.844-849
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• 2022

The pathogenic Vibrio genus denotes halophilic bacteria that are distributed in aquatic environments, including both sea and freshwater. V. cholerae, V. vulnificus, and V. parahaemolyticus are the main species that can be potent human pathogens and the leading cause of septicemia, wound infections, and seafood borne gastroenteritis. The aim of this study was to investigate the presence of pathogenic Vibrios in seawater. We obtained a total of 80 seawater samples from the Geum River estuary area in the west coast of Korea from April to December 2021. Pathogenic Vibrios was determined using a combination of the most probable number-polymerase chain reaction (MPN-PCR) methods. The detection levels of V. cholerae, V. parahaemolyticus, and V. vulnificus in the seawater samples were 7.5%, 68.8%, and 30.0%, respectively. The quantitative results were as follows: 3.6-3.6 MPN/100 mL in V. cholerae, 3.6-3,400 MPN/100 mL in V. parahaemolyticus, and 3.6-4,300 MPN/100 mL in V. vulnificus. Overall, these results provide novel insight into the necessity for seawater sanitation in the Geum River estuary area, and could help reduce the risk of seafood-borne outbreaks caused by pathogenic Vibrios.

• Journal of Korea Water Resources Association
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• v.48 no.8
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• pp.647-657
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• 2015

This study assessed the water use vulnerability for 12 basins of South Korea. The annual runoff of 12 basins are derived using a Soil and Water Assessment Tool (SWAT) and the calculated runoff per unit area and population are compared with each basin. The 18 indicators are selected in order to assess the vulnerability. Those are classified by aspects of demand, loss and supply of water use. Their weighting values used Entropy method to determine objective weights. To quantitatively assess the water use vulnerability, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) based on multi-criteria decision making are applied. The results show that the water availability vulnerability of Hyeongsan River has the highest value followed by Sapgyo River; Dongjin River; Seomjin River; Anseong River; Mangyung River; Nakdong River; Tamjin River; Youngsan River, Geum River; Taehwa River; and Han River. The result of this study has a capability to provide references for the index deveopment of climate change vulnerability assessment.

• Journal of Korea Water Resources Association
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• v.40 no.1 s.174
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• pp.63-72
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• 2007

The main purpose of this study is that financial resources allocation criteria are examined closely between central government and local government as well as among local government in a river basin. Financial resources allocation principles reflecting water use, flood control, and water quality improvement are reviewed and derived two categories such as common factors and individual factors. The weights of each factor are assigned by analytical hierarchy process. The results of applying four river basins (Han river, Geum river, Nakdong river, Yeongsan-seumjin river) show that rational raising of financial resources are different according to the characteristics of each river basin. Findings are as follows: In case of Han river and Yeongsan Seumjin river, benefit principle and polluter pay principle by individual factors are more attractive than other Principles. Solvency principle by common factor is more acceptable than the other principles in Nakdong-river and Geum-river.

• Journal of Korean Society on Water Environment
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• v.22 no.3
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• pp.504-512
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• 2006

In order to estimate microbial contaminant discharge from diffuse sources, rainfall runoff was monitored at forestry, agriculture and urban watersheds. Total coliform and E. coli were monitored at the study watersheds as they are regulated by the environmental laws. Concentration and EMC (Event Mean Concentration) of coliform of rainfall runoff at the urban watershed were the highest followed by those from agricultural and forestry watersheds. By monitoring coliform concentrations of overlying water and sediment at five monitoring points in the downstream of the Geum River, average concentration from spring to summer was higher than those values from fall to spring. Coliform concentrations in the pore water were higher compared to those of overlying water and closely related with flow rate of the river.

• Ecology and Resilient Infrastructure
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• v.6 no.4
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• pp.287-294
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• 2019

This study investigated longitudinal changes in riverbed materials properties and temporal alteration of river channel geomorphology in the Geum River basin, where two multipurpose dams(Yongdam Dam and Daecheong Dam) were built in upstream area. We carried out grain size distribution analyses and measured soil organic matter contents of riverbed materials taken at the upper and lower sites of the two large dams. We also estimated the channel width, bar area and vegetation encroachment using the oldest map and aerial photographs taken before and after the construction of the dams. The results can contribute to increasing understandings of dam induced habitat alteration in river ecosystem.

• Journal of Korea Water Resources Association
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• v.45 no.10
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• pp.983-995
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• 2012

In this study, it was intended to analyze the spatio-temporal distribution of historical drought events occurred in Korea by way of drought frequency analysis using SPI (Standardized Precipitation Index), and Drought spell was executed to estimate drought frequency as per drought severity and regions. Also, SDF (severity-duration-frequency) curves were prepared per each weather stations to estimate spatial distribution characteristics for the severe drought areas of Korea, and Potential Drought Hazard Map was prepared based on the derived SDF curves. Drought frequency analysis per drought stage revealed that severe drought as well as extreme drought frequency were prominently high at Geum River, Nakdong River, and Seomjin River basin as can be seen from SDF curves, and drought severity was found as severer per each drought return period in the data located at Geum River, Nakdong River, and Seomjin River basins as compared with that of Seoul weather station at Han River basin. In the Potential Drought Hazard Map, it showed that Geum River, Seomjin River, and Yeongsan River basins were drought vulnerable areas as compared to upper streams of Nakdong River basin and Han River basin, and showed similar result in drought frequency per drought stage. Drought was occurred frequently during spring seasons with tendency of frequent short drought spell as indicated in Potential Drought Hazard Map of different season.

• Journal of the Korean association of regional geographers
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• v.17 no.6
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• pp.666-678
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• 2011

This study is aimed to examine the variability of consecutive dry days in South Korea. The country is divided into six basins including Han river, Nakdong river, Geum river. Seomjin Yeongsan river, Eastern Coast area and Island area, and three extreme precipitation indices-related to dry days are analyzed at sixty weather stations. Trends of max number of consecutive dry days were unstable during 1973~2010. Variability range of max number of consecutive dry days trends in Nakdong and Seomjin Yeongsan river was larger than that in Han and Geum river. Recently, the range in Nakdong and Seomjin Yeongsan river was bigger and bigger. Maximum dry spell was observed in autumn and winter in most of riverbasins. Especially, Maximum dry spell in winter was more frequent than in other seasons in Nakdong river. Variability range of persistence dry spells was smaller than that of max number of consecutive dry days. However, the increasing trends of the Geum river and the Seomjin Yeongsan river are statistically significant in recent. In Nakdong river, difference between persistence dry spell average and persistence dry spell median was larger than any other riverbasin. It means that there is strong possibility of occurrence of long term consecutive dry days in Nakdong river.