• Water for future
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• v.18 no.1
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• pp.67-73
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• 1985

Tidal propagation in the Keum River has been routinely handled by numerical integration of the long fravity wave equation by Dronkers. The dynamic equations include non-linear terms thereby reproducing the shallow water tides. The model was used to compute tidal distribution of the Kum River for aveage spring, mean, neap tidal conditions and further utilised to investigate the waterlevel response within tidal reaches by combined tide and flood discharge effects. The objective of this initial study is to investigate the tidal dynamics of the lower reaches of the Keum River under the condition of before-cross-channel barrage construction.

• Magazine of the Korean Society of Agricultural Engineers
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• v.22 no.2
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• pp.55-63
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• 1980

To study run-off characteristics in the small watersheds in Korea, investigations had been carried out for a period of 4 years from 1972 to 1975 in the sample watersheds. The samples were selected in four major river basins such as the Han River, the Keum River, the Nakdong River and the Yongsan River. Water levels and rainfall data had been. collected from each sample area where the measuring instruments were installed. The findings of this investigation can be summarized as follows; 1. With an average runoff rate of 60% in the sample watersheds, the average runoff rate. in each sample proved to be as below; the Han River Basin : 41.4% the Keum River Basin : 61.7% the Nakdong River Basin : 69.4% the Yong San River Basin : 69.2% 2. The base flow rate in the sample watersheds proved to be 8.1 mm/month. 3. A comparison of the runoff obtained from actual measurements made and that calculated by the Kaijyama formula showed that the latter is 9.1% lower than the former.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.348-354
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• 2001

This study was conducted to estimation of change characteristics for water quality by the dyke gate operation in the Keum River estuary. The estimation data made use of surveyed data in Keum River estuary by NERDI (National Fisheries Research and Development Institute) during $1990\~1999$. Shown to compare water quality changes at st. A and st. D in Figure 1, the concentrations of TSS, COD and nutrients at st. A were as high as about $2\~4$ times than those at st. D due to affection of fresh water discharge in the Keum River. The percentages of water quality change at surface water by dyke gate operation in the Keum River estuary were shown that TSS (Total Suspended Solid) was decrease to $56\%,\;47\%$ at st. A and D, and COD (Chemical Oxygen Demand) was increase to $68\%,\;71\%$ at st. A and D, respectively. The changes percentage of DIN (Dissolved Inorganic Nitrogen) by dyke gate operation in the Keum River estuary were increase high to $95\%$ at surface water and $7\sim30\%$ at bottom water, but those of DIP (Dissolved Inorganic Phosphorus) were increase to $2.8\sim8.6\%$ at surface water and $28\%$ at bottom water. The range of fluctuation for water quality at each station by dyke gate operation has shown that salinity and TSS are little better than before dyke gate operation, but COD show highly fluctuation. Also we studied estimation of characteristics of water quality change by the season, COD was increased except the summer, TSS was decreased to all season. DIN was increased to about $61\sim172.1\%$ for all season, but DIP was increased to the spring and decreased to the autumn, DIN enrichment in the estuary by dyke gate operation are interpreted to improvement of organic matter decomposition and nitrification by increasing the residence time and to increase nutrient flux in sediments due to decreasing dissolved oxygen and increasing a deposit matter.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.3
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• pp.289-296
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• 2002

Using results obtained from field surveys in the outflow region of the Keum River in winter (February 22), spring (May 9), summer (July 31) and autumn (October 17) in 2000, it was described the nutrient front relating to the hydrography. It showed that the horizontal gradients was sharp in the distributions not only in salinity but also in nutrients in the region of the mouth of estuary far away about 20 km from the dyke of the Keum River during the year. The two layer structure was a ubiquitous feature in the inner estuarine side of the region showing the maximum horizontal gradients in salinity and nutrients. Although the absolute values in salinity and nutrient concentrations were distinguished by season, the nutrient front seperates the saltier and nutrients poor water in the open sea from the brackish and nutrients rich water of the plume. These results suggest that the nutrient front coincides with the esturine front in the region of freshwater influence (ROFI) of the Keum River.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.5
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• pp.68-76
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• 1999

The purpose of the study was to investigated the change of hydraulic characteristics like water surface profile and rivered section in the down stream of Keum river after the construction of esturary dam. The effect of esturary dam on the flood control in the Keum river was recognized with the data of two flood events happened in July, 1987 before the construction and in August, 1995 after the construction of estuary dam. For example , duration time above the water level of the warning -flood was changed from 46.5 to 42.8 hours and duration time above the eater level of the danger-flood was changed from 24.7 to 19.8 hours at the Kyuam station. The time difference to reach the water level of the designated -flood between Kyuam and Kangkyung was changed from 3 hours in 1987 to 12 hours and 20 minutes in 1995. The water surface slope of river decreased 25.6% between estuary dam and Kangkyung and increased 16.5% between Kangkyung and Kyuam, and decreased 8.8% between Kyuam and Kongju. As the result, velocity was getting faster and river bed was scoured in the reach of Kangkyung and Kyuam, and velocity was getting slower and river bed was sedimented in the reach of Kangkyung and estury dam.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.5
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• pp.685-694
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• 1998

To evaluate the water quality characteristic after construction of Keum river estuary barrage, water quality analysis were conducted on August October in 1995 and January, May in 1996 respectively. The results were summarized as follows. The concentrations of COD were in the range of 1.01~5.10 (mean 2.50)mg/$\ell$ for surface water and 0.51$\~$6.68 (1.88)mg/$\ell$ for bottom water. The concentrations of dissolved inorganic nitrogen (DIN) were in the range of 1.26$\~$105.91 (29.66)$\mu$g-at/$\ell$ for surface water and 1.42$\~$68.38 (19.12)$\mu$g-at/$\ell$ for bottom water. The concentrations of phosphate phosphorus were in the range of ND$\~$0.99 (0.34)$\mu$g-at/$\ell$ for surface water and 0.17$\~$1.04 (0.49)$\mu$g-at/$\ell$ for bottom water. The nitrogen ratio to the phosphorus were as high as 3.5$\~$849.5 (146.5). Therefore, Phosphate phosphorus was playing an important role in phytoplankton growth as limiting factor in Keum river estuary. The correlation coefficient of salinity and DIN according to COD was shown to -0.757 and -0.874 respectivity. Mean values of eutrophicaton indies were calculated to 9.7, 7.2 for surface and bottom water, these values were exceeding 1, the value of eutrophication criteria. Especially station 1$\~$3 were shown over 10 as eutrophication indices. Therefore, Keum river estuary could be evaluate to possibility area for breakout of red tides.

• Journal of Environmental Science International
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• v.10 no.2
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• pp.119-127
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• 2001

The Keum river is one of the important river in Korea and has a drainage area of 9,873$\textrm{km}^2$. The Keum river is deepening pollution state due to development of the lower city and construction of a industrial complex. The water quality of the Keum river come to eutrophication state and belong to III grade of water quality standard. The concentration BOD in river is affected by the organic loading from a tributary and the algae biomass that largely happen to under eutrophication state. In the eutrophic water mass such as the Keum river, the autochthonous BOD was very important part for making a decision of water quality management, because it was accounted for majority of the total BOD. The purpose of this study was to survey the chatacteristics of water quality in summer and to estimate reaction coefficient. Also, we studied to correlationship between chlorophyll a and BOD(COD) for estimation of the autochthonous BOD. The correlationship between chlorophyll a and BOD(COD) were obtained through the culture experiment of phytoplankton in the laboratory. The results of this study may be summarized as follows ; The characteristics of water quality in summer were belong to III~IV grade of water quality standard as BOD and nutritive condition is very high. The BOD, ammonia nitrogen and phosphate loadings in Miho stream which inflowing untreated sewage from Chungju city was occupied with 64.07%, 26.36%, 46.08%, respectively. Maximum nutrient uptake (Vmax) was 0.4400$\mu$M/hr as substrate of ammonia nitrogen, 0.1652$\mu$M/hr as substrate of phosphate. Maximum specific growth rate ($\mu$max) was 1.2525$hr^{-1}$ as substrate of ammonia nitrogen, 1.5177$hr^{-1}$ as substrate of phosphate. The correlation coefficient between chlorophyll a and BOD by the culture experiment were found to be 0.911~0.935 and 0.942~0.947 in the case adding nutrient and no adding nutrient, respectively. The correlation coefficient between chlorophyll a and COD through the culture experiment were found to be 0.918~0.977 and 0.880~0.931 in the case adding nutrient and no adding nutrient, respectively. The autochthonous BOD(COD) was estimated to the relationship between BOD(COD) and chlorophyll a. The regression equation were found to be autochthonous BOD=(0.045~0.073)${\times}chlorophyll$ a and autochthonous $COD=(0.137~0.182){\times}chlorophyll$ a.

• Water Engineering Research
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• v.1 no.4
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• pp.299-307
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• 2000

The method for estimating the minimum instream flows required for the riverline aesthetics, proposed by the Kim et al.(1996), has been applied to the main channel reach of the Keum river basin in Korea. To determine the minimum instream flows for eight main reaches at Keum river basin, six representative stations have been selected. This paper provides an analysis of influence on the riverline aesthetics, which is affected by change of physical components of river, by using the survey-based quantification method. The developed questionnaire based on the literature, and submitted to the 326 people who visited an each representative station. This surveying had been implemented in three times at each representative station and we had been selected a different flowrate at each implementation. The results of this analysis and survey have produced the relationship between the variation of physical components and riverline aesthetics. Survey results bout the flow comparison are summarized as follows. At the view of riverline aesthetics, most of the respondents re sensitive at the change of the flow velocity and they prefer high water level to low water level. Moreover whole respondents prefer to abundant stream flows and moderate flow velocity. The minimum flows for riverline aesthetics is estimated at each representative station by using the survey-based quantification method and the estimated results of some representative station are greater than mean monthly flow at each station. The result of the analysis appears that establishing minimum instream flows for riverline aesthetics is not only a technical problem but a legal problem. Therefore in the case of establishing the instream flows in the river, the estimated results have to be considered as relative standard.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.8 no.4
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• pp.52-67
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• 2005

The flora of the studied basin in the upper Keum River was listed as 237taxa; 63families, 162genera, 212species, 22varieties and 3forms. Based on the list of the ecosystem disturbance plants by the Ministry of Environment, 4taxa were recorded in the studied basin : Paspalum distichum(Gramineae), Paspalum distichum var. indutum(Gramineae), Ambrosia artemisiifolia var. elatior(Compositae), Ambrosia trifida(Compositae). Naturalized plants was listed as 54taxa; 16families, 41genera, 51species, 3varieties and naturalization index was 22.8percent of 1/4 the vascular plants. Upper Keum River was dominant floristic : indicator species were Salix gracilistyla community, Phragmites japonica community, native plants were Morus alba community, Spiraea prunifolia for. simpliciflora community, planting plants were Populus euramericana community, naturalized plants were Solidago serotina community, Helianthus tuberosus community.

• The Korean Journal of Quaternary Research
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• v.20 no.2
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• pp.1-10
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• 2006

Flooding hazard caused by natural and artificial environmental changes is closely associated with change in river bed configuration. This study is aimed at explaining a river-bed change related to soil erosion in the Keum river basin using GIS and RS. The USLE was used to compute soil erosion rate on the basis of GIS. River-bed profiles stretching from Kongju to Ippo were measured to construct a 3D-geomorphological map. The river-bed change was also detected by remote sensing images using Landsat TM during the period of 1982 to 2000 for the Keum river. The result shows that USLE indicates a mean soil erosion rate of $1.8\;kg/m^2/year$, and a net increase of a river-bed change at a rate of $+5\;cm/m^2$/year in the Kangkyeong area. The change in river-bed is interpreted to have been caused by soil erosion in the downstream of the Keum river basin. In addition river-bed change mainly occurred on the downstream of the confluence where tributaries and the main channel meet. Other possible river-bed change is caused by a removal of fluvial sand aggregates, which might have resulted in a net decrease of exposed area of sediment distribution between 1991 and 1995, while a construction of underwater structures, including a bridge, a reclamation of sand bars for rice fields and dikes, resulted in an increase of the exposed area of river-bed due to sediment accumulation.