• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.3
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• pp.154-163
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• 2005

Irregular discharges of freshwater through the water gates of the Keum River Estuarine Weir, Korea, whose construction had been completed in 1998 with its water gates being operated as late as August 1994, drastically modified the estuarine environment. Sharp decrease of salinity along with the altered concentrations of inorganic nutrients are accompanied with the irregular discharges of freshwater into the estuary under the influence of regular semi-diurnal tidal effect. Field sampling was carried out on the time of high tide at 2 fixed stations(St.1 near the Estuarine Weir and St.2 off Kunsan Ferry Station) every other day for 4 months from mid-February 2004 to investigate into the semi-weekly variation of spring phytoplankton community in relation to the freshwater discharges from Keum River Estuarine Weir. CV(coefficient of variation) of salinity measurements was roughly 2 times greater in St.1 than that in St.2, reflecting extreme salinity variation in St.1 Among inorganic nutrients, concentrations of N-nutrients($NO_3^-,\;NO_2^-$ and $NH_4^+$) were clearly higher in St.1, to imply the more drastic changes of the nutrient concentrations in St.1. than St.2 following the freshwater discharges. As a component of phytoplankton community, diatoms were among the top dominants in terms of species richness as well as biomass. Solitary centric diatom, Cyclotella meneghiniana, and chain-forming centric diatom, Skeletonema costatum, dominated over the phytoplankton community in order for S-6 weeks each (Succession Interval I and II), and the latter succeeded to the former from the time of <$10^{\circ}C$ of water temperature. Cyanobacterial species, Aphanizomenon Posaquae and Phormidium sp., which might be transported into the estuary along with the discharged freshwater, occupied high portion of total biomass during Succession Interval III(mid-April to late-May). During this period, freshwater species exclusively dominated over the phytoplankton community except the low concentrations of the co-occurring 2 estuarine diatoms, Cyclotella meneghiniana and Skeletonema costatum. During the 4th Succession Interval when the water temperature was over $18^{\circ}C$, the diatom, Guinardia delicatula, was predominant for a week with the highest dominance of $75\%$ in discrete samples. To summarize, during all the Succession Intervals other than Succession Interval III characterized by the extreme variation of salinity under cooler water temperature than $18^{\circ}C$, the diatoms were the most important dominants for species succession in spring. If the scale and frequency of the freshwater discharge could have been adjusted properly even during the Succession Interval III, the dominant species would quite possibly be replaced by other estuarine diatom species rather than the two freshwater cyanobacteria, Aphanizomenon flosaquae and Phormidium sp.. The scheme of field sampling every other day for the present study was concluded to be the minimal requirement in order to adequately explore the phytoplankton succession in such estuarine environment as in Keum River Estuary: which is stressed by the unpredictable and unavoidable discharges of freshwater under the regular semi-diurnal tide.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1995.10a
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• pp.44-47
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• 1995

연안 해역에 있어서 해양환경의 변화는 자연적인 요인과 인위적 요인으로 구분할 수 있다. 최근 산업발달과 더불어 진행되어진 연안역에서의 대규모 공사들은 해양환경변화의 인위적 요인으로 작용하여 인근해역에 부유사 및 소류사의 침전과 세굴을 초래하며 해수유동을 변화시켜 장기적인 퇴적환경의 변화를 초래하고 있다. 특히 본 연구의 대상지역인 금강하구역은 지난 십여년 동안 대규모의 공사들이 시행되어 왔으며, 최근 외항 부근에서 집중적인 공사가 진행중이고 금강하구둑의 수문이 ＇94년 8월 31일 부터 패쇄되어 해수유동 및 퇴적환경의 일대 변화가 예상된다. (중략)

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.507-511
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• 2005

본 연구에서는 수자원 지속가능성 지수(WRSI)를 금강유역에 적용하여 소유역별 수자원 지속가능성을 평가하였다. WRSI의 적용을 위하여 금강유역을 주요 계측지점의 위치와 자료수집의 용이성을 고려하여 27개의 소유역으로 분할하였다. WRSI 산정의 효율성과 정확성을 확보하기 위하여 소유역별 사회, 경제, 환경과 관련된 통계자료에 대한 GIS 주제도를 구축하였다. WRSI를 구성하는 지표들의 표준화는 적정확률분포형을 적합도 검정을 실시한 후 초과확률을 산정하는 방법을 적용하였다. WRSI를 이용하여 금강유역의 소유역별 수자원 지속가능성 지수를 산정한 결과, 금강유역의 소유역별 수자원 지속가능성 지수는 하류에 위치한 유역들보다 상류에 위치한 유역들이 큰 값을 나타냈다. 수자원 지속가능성 지수의 지표들간의 상관관계를 분석하기 위하여 상관분석을 실시한 결과, 사회적 공평성 세부지수를 구성하는 지표들과 유지관리 능력 세부지수를 구성하는 지표들간의 상관성이 높은 결과를 나타냈다.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.276-276
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• 2011

우리나라는 강우의 계절적 편기가 심하여 겪는 홍수 조절의 어려움 이외에도 최근 생 공 용수의 증가와 더불어 생태학적 환경 보전, 미관을 위한 물 수요등이 증가, 홍수 범람구역 내의 인구 밀도의 상승과 산업의 증대, 수해 내성이 취약한 전자 통신망의 구축 등에 따라 홍수 피해가 발생할 경우 그 피해가 막대하다. 따라서 실제적으로 보(weir) 운영은 홍수와 이수를 고려하여 운영한다. 이러한 점에서 본 연구는 이수를 고려한 직렬보의 홍수기 운영시 예비방류의 효과에 대하여 논하였다. 예비방류는 다음과 같은 방식으로 도입한다. 1)홍수 조절용량의 일부를 이수용량으로 할당한다. 2)홍수가 예상될 경우 이수용량의 일부를 홍수조절을 위해 이용한다. 3) 홍수조절후 예비방류로 초기 저수위를 확보하지 못하는 경우 이수용량의 감소에 따른 벌칙을 가한다. 제시된 기법을 기상청의 강우 예보자료를 이용하여 낙동강의 실제 홍수사상에 대해 적용하였다.

• Journal of the Korean earth science society
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• v.29 no.4
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• pp.328-340
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• 2008

To discriminate the provenance of shelf sediments in the western part off Jeju Island, the textual and elemental compositions were analyzed and compared with the sediments originating from Changjiang and Huanghe Rivers of China and the Korean (Keum) River. The sediments in the study area are composed of coarse silt with a mean pain size of $3.6{\sim}8.5{\phi}$ and their $CaCO_3$ contents ranged from 0.92 to 9.75 wt.%. The ratios of TOC over total nitrogen (TN) showed that the study area sediments contained more organic matters of marine origin than those of terrigenous origin. The high concentration of Fe/Al, Ti/Al and Mn/Al figures were found in the southwestern part near the Changjiang esturay, indicating that it seemed to result from the influence of the Changjiang River. The discrimination diagrams including Sc/Al vs Cr/Th, Th/Sc vs Nb/Co and Ti/Nb vs Th/Sc were thus used as provenance indicators to identify the sediment origins of the western part off Jeju Island. Based on these discriminated diagrams it clearly showed that most of the sediment in the western part were originated from the Huanghe River, but the sediments in the southwestern part near the Changjiang esturay might come from the Changjiang River. In contrast, the sediment samples of the northeastern part showed the higher figures than those of the river sediments and other regions, suggesting that the sediments in the western part off Jeju Island must be originated from diverse sources.

• Journal of Wetlands Research
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• v.17 no.1
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• pp.91-100
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• 2015

The aim of this study is to compare and analyze plant monitoring results of 2012 and 2013 for three artificial wetlands of Binae, Sedo, and Okpo areas in Namhan river, Keum river, and Nakdong river respectively. As the results, the Binae wetland in 2013 shows the same environment with 2012, that is, Willow and Common reed were dominant and the distributed plants in the wetland were Phragmites japonica Steud, Carex dispalta Boott, and Humulus japonicus in lowland of river side. Especially, Humulus japonicus was increased in summer season and Willow was increased in lowland of 초원. In Okpo wetland, Water chestnut was appeared in 2013 which it was not in 2012. Reed distribution was reduced in 2013 comparing to 2012 but Pussy willow distribution was not changed in 2013. In Sedo wetland, Secondary grassland was artificially planted in 2013 and so the colony was changed to Chinese Lespedeza and also most of plant colony was changed to Colt's-tail. Therefore, we can know that wetted transition rather than dried transition will be occurred in the Binae wetland. However, the Okpo wetland has monotonic change and so the transition will be proceeded with long time. The Sedo wetland showed wetted and dried transitions exist together. Therefore, the wetland will be changed to Reeds, Common reed, and Willow colonies.

• Journal of Wetlands Research
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• v.15 no.4
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• pp.529-534
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• 2013

Domestic water pollution accidents and response management were analysed on the basis of collected data from the latest 5 years. Although average 66.7 number of accidents were happened every year, no damages of human life were reported yet. According to the data collected, the accidents were occurred at Han river, Nakdong river, Keum river, Youngsang river and other rivers, where the percentages were 25.4%, 20.3%, 12%, 8% and 29.7%, respectively. Main reasons were blamed for negligent management, mixed influences, natural phenomenon and traffic accident. Response activities were performed in the case of the oil leak, the fish death caused by water environment, the spill of chemicals. From the diagnosis of water pollution accidents, it is recommended that the legistration of all control centers for their roles and duties was made in case of the big accidents as well as the small/middle accidents.

• Journal of Soil and Groundwater Environment
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• v.14 no.2
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• pp.10-16
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• 2009

Characteristics of natural radioactivity were investigated for soils collected from seven sites of different bed rocks distributed in the Keum River area of Korea by the use of a Gamma-ray spectrometry. Specific activity (SA) and SA ratio (SAR) of typical naturally occurring radioactive nuclide such as $^{226}$Ra, $^{228}$Ac and $^{40}$K were determined for the soil samples. The SA values of $^{226}$Ra, $^{228}$Ac and $^{40}$K in 41 soils of 7 sites are 26.7-485 (74.2 ${\pm}$ 72.2), 30.9-157 (90.7 ${\pm}$ 32.7) and 203-1558 (990 ${\pm}$ 203) Bq/kg, respectively. The SA of $^{226}$Ra has very different values by the soils and the sites. Especially the SA of $^{226}$Ra in a soil sample of Ogcheon site is 485 Bq/kg while most SA of 41 soil samples are < 100 Bq/kg. SA of $^{228}$Ac has a little different values with the soils and sites, however the SA of $^{40}$K has almost constant values in all soil samples. The SAR values of $^{26}$Ra/$^{228}$Ac, $^{226}$Ra/$^{40}$K and $^{228}$Ac/$^{40}$K in 41 soils of 7 sites are 0.343-6.11 (0.865 ${\pm}$ 0.883), 0.0258-0.759 (0.0814 ${\pm}$ 0.1l17) and 0.0373-0.178 (0.0945 ${\pm}$ 0.0373), respectively. The SARs of $^{226}$Ra/$^{228}$Ac and $^{226}$Ra/$^{40}$K have very different values by the soils and the sites, however the SAR of $^{228}$Ac/$^{40}$K has a little difference by the soil and sites.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.3
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• pp.115-125
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• 2001

To examine the movement of the freshwater discharged artificially into the estuary during ebbing period in the Keum River dike we observed surface salinity variations in three stations along the estuary channel in May 1998 and July 1997 and surface temperature and salinity along the ferry-route between Kunsan and Changhang during eighteen days in July 1999. Based upon the typical features of observed salinity variation, we analyzed the excursion and decay processes of the discharged water. When freshwater is discharged, the low-salinity water forms strong salinity front over the entire estuary width, which basically moves forth and back by tidal modulation along the channel, producing the sudden change of surface salinity with the front passage. Salinity distribution along the channel, which is deduced from time variation of mean salinity over the estuary width, after one tidal period from gate operation suggests that diluted low-salinity water is trapped to the front and surface salinity increases gradually toward the upstream region. This frontal distribution of salinity is interpreted to be produced by the sudden gate operation supplying and stopping of freshwater within about two hours. Daily repeat of freshwater discharge produces separation (double front) or merge between decaying and new-generated fronts depending on dike-gate opening time, and the front decays with salinity increasing if the freshwater supply is stopped more than two days. In addition, the observed fluctuations and deviations in surface salinity variation is explained in terms of the differences of fronts intensity, their transition time and temporal salinity front running along the channel, which can be generated due to artificial gate-operation for the discharging time and water volume in the estuary dike.

• The Korean Journal of Quaternary Research
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• v.7 no.1
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• pp.69-91
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• 1993

A total of 76 surface sediment samples, collected from the Korean west coast and the eastern Yellow Sea areas, were analyzed for their elemental composition in order to understand the geochemical characteristics of these deposits. The analyzed elements included 9 major elements (Al, Fe, Na, K, Mg, Ca, Ti, P, Mn), 8 minor elements (Sr, Ba, V, Cr, Co, Ni, Cu, Zn), organic carbon and calcium carbonate. Contents of most analyzed elements, excluding K and Ba, were generally low compared to those of average crust. Contents of most elements, except K and Ca, also correlated with sediment grain size, though the degree of relationship varied widely from one element to another. For fine-grained sediments, a distinction could be made between those in the central Yellow Sea and those in the Keum Estuary based on their characteristic elemental composition: the former were rich in Fe, Na, K, Mg, Ca and V, and the latter in Mn, Co and Ni. The element/aluminium ratios, on the other hand, showed that the central Yellow Sea muds were enriched in Fe, Mg, V, Ni, Cu and Zn and depleted in K, Mn, Ba and Sr relative to the mud located near the Korean Peninsula. Based on the analysis of these results, as well as of the influences of particular mineral phases or pollution effects, we could suggest geochemical criteria which can be used in distinguishing muds from the two different sources, the Keum River and the Yellow River: the former by the higher Mn content and the latter by the higher Mg and V contents, relative to each other.