• Korean Journal of Environmental Biology
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• v.23 no.2 s.58
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• pp.120-128
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• 2005

This study was compared the flora and distribution of hydrophytes with physicochemical environment in the 14 sites selected in Yeongsan River through Gwangju Metropolitan city from March to October, 2003. In this survey, hydrophytes were classified 94 taxa; 35 families, 68 genera, 85 species and 9 varieties. It was compared the physicochemical characters with the hydrophytes distribution in each stream according to the index of contamination. Persicaria japonica and Rumex crispus were dominated at Youduk-Dong, the most contaminated area. Aquatic contamination sensitive floating-leaved plants and submerged plants were not identified. Hwangroung River and Yeongsan River area were a little contaminated area, appeared to good vegetation such as Phragmites japonica, Persicaria thunbergii and Miscanthus sacchariflorus. The stream of Youduk-Dong, the lower reaches of Gwangju-cheon was not grown with hydrophytes because of contamination by inflow of life sewage; therefore it is required to persevere in the townsmen's efforts for improvement of water environment.

• Journal of Korean Society on Water Environment
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• v.29 no.4
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• pp.523-530
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• 2013

This study has been carried out to clarify the characteristics of discharge and pollutant loading according to flow conditions at jiseok stream watershed (JSW). A flow rate and pollutant load in the study watershed were estimated by equation of stage-discharge and discharge-loads rating curve. By using the methods above, I've evaluated the water quality (WQ) of the JSW if it is satisfied with the standard target. I've collected the data of BOD and T-P from the JSW every 8 days for the duration of 12 months. And then, I've schematized the data upon the load duration curve and the results showed me that the WQ of JSW was satisfied with the standard target. I've also collected the same data every each day for the duration of 12 months from JSW and have schematized the data again. And the results showed that it also was satisfied with the standard target. To be concluded, I've determined that point pollution sources of JSW gives more significant impacts to the WQ than non-point pollution sources of JSW and hence, as time goes, point pollution sources will keep depriciating the WQ of JSW. Therefore, further efforts will be required to JSW to maintain the WQ.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1182-1186
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• 2006

The decision of design flood in river basins is very important in the aspect of flood control. The design flood of rivers was estimated according to the size and importance of basins. As the damage of floods increases more and more and the importance of defense against floods increases further, the presumption of design flood can be very important. Especially, what influences most greatly flood is rainfall. However, in spite of equal rainfall, the estimated flood differ according to the features of basins. The fact that the features of basins influence greatly the estimation of flood was confirmed by the preceding research results and experiences. However, although many rivers have their own basin features, the research on how these basin features are related to the estimation of design flood, is not yet sufficient. The purpose of this study is to identify how the design flood estimated previously by river arrangement basic plan is correlated with topography factors, and so investigate the correlation between basin topography factors and design flood in order to provide the additional information for the unmeasured basins or the middle/small river basins where their river plan is not established.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.930-940
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• 2013

We evaluated contamination with organic matter and trace metals by analyzing grain size, ignition loss (IL), chemical oxygen demand (COD), acid volatile sulfide (AVS), and trace metals (Al, Fe, Cu, Pb, Zn, Cd, Ni, Cr, Mn, Hg, and As) in surface sediments at 28 stations around the Geum River estuary in July 2008. The surface sediments in the estuary were mainly composed of coarse sediment (sand and muddy sand), with mean grain size (Mz) ranging between $2-4{\O}$. The high concentrations of IL, COD, and trace metals were mainly found at stations in front of the Gusan outer port and industrial complex, and near the Seocheon coast with relatively fine sediments. In addition, the concentrations of IL and all trace metals, except Pb and As, showed good positive correlations with Mz, indicating that the concentrations of organic matter and trace metals were mainly dependent on sediment grain size. The concentrations of COD, AVS, and trace metals in most sediments did not exceed the sediment quality guideline (SQGs). Although the sediments in the study region are not polluted with organic matter and trace metals, there are many point sources of pollutants, such as Gusan port and industrial complex, Janghang refinery, and a thermoelectric power plant around the Geum River estuary. Thus, the management of coastal environments through periodic monitoring of organic matter and trace metals is required in the future.

• Korean Journal of Ecology and Environment
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• v.47 no.4
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• pp.292-301
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• 2014

Akinete germination may be a starting point of some akinete-producing cyanobacterial blooms in eutrophic freshwater systems. This study examined germinability of akinete of a cyanobacterium Anabaena circinalis isolated from the sediment of the North Han River (Cheongpyung Dam), Korea, under several environmental factors such as temperature ($5{\sim}25^{\circ}C$), light ($0{\sim}100{\mu}mol\;photons\;m^{-2}\;s^{-1}$), nutrients (nitrogen and phosphorus) and pH (5~12). The high germination rate appeared at high temperature: >55% at $25^{\circ}C$, followed by 15% at $15^{\circ}C$, $10^{\circ}C$ and 10% at $5^{\circ}C$. Low light intensity was favorable for akinete germination. Over 45% of germination occurred at low light intensities (5, 15 and $30{\mu}mol\;photons\;m^{-2}\;s^{-1}$), while less than 10% of germination occurred at both 50 and $100{\mu}mol\;photons\;m^{-2}\;s^{-1}$. No germination occurred in the dark condition. Akinete germination rate increased with nutrient (phosphorus and nitrogen) enrichment, and nitrogen addition showed greater effect on the germination compared to phosphorus addition. Akinetes germinated well at neutral or slightly alkaline pH condition (pH 7 and pH 8: >55%), but no germination was observed at pH 11~12. The present study demonstrates some favorable ambient conditions of Anabaena circinalis germination, which could provide useful information to study the germination conditions of other Anabaena species or akinete-forming algae and predict its bloom in eutrophic freshwaters.

• Korean Journal of Ecology and Environment
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• v.47 no.1
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• pp.1-12
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• 2014

Some blue-green algal species such as those in the genus Anabaena causing severe algal blooms can produce akinetes, resting spores, in aquatic ecosystems. Germinated akinetes staying in the sediment as "seed banks" grow into vegetative cells under favorable conditions of light intensity, nutrient, and temperature. Therefore, akinete plays an important role in forming the nuisance bloom. However, little information is available in the ecological study of akinetes compared to that of vegetative cells in Korea. This review reports ecological and physiological characteristics of akinetes, especially of the blue-green algal genus Anabaena. We also suggest the feasible area of akinetes in the freshwater ecosystems. We expect that the suggested studies associated with akinetes will contribute to further understanding the life cycle and ecology of Anabaena and other algae.

• Journal of Korean Society on Water Environment
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• v.28 no.6
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• pp.813-818
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• 2012

BOD and COD are currently used for water quality indices, but adoption of TOC for TMDL (Total Maximum Daily Load) is being suggested. Estimation of TOC using existing BOD and COD data is very important to diagnosis water quality trend when TOC is used for water quality index of organic matter in the future. The relationships between BOD COD and TOC in runoff from paddy fields were investigated during 2008-2011. The observed mean concentration of EMCs (Event Mean Concentration) for BOD, COD, TOC were 3.87, 10.97, 7.26 mg/L respectively. The correlation coefficients between BOD-TOC and COD-TOC were 0.42, 0.73, respectively. The coefficient of determination of regression equation for BOD-TOC and COD-TOC were 0.18, 0.53 respectively. Even though, conversion of COD data to TOC seems to be rather reliable than that of BOD-TOC, further monitoring is recommended to ensure better interpretation of relationship among BOD, COD and TOC.

• Journal of Korea Water Resources Association
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• v.31 no.4
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• pp.503-512
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• 1998

When various elements of water balance are displayed at several points of a river network, the runoff amounts at an estuary especially tidal influenced are affected from the elements. This problem can be solved by a model that can generalize and formulate the elements and simulate daily runoff and water requirement. The WWASS model was built using DIROM for the simulation of daily runoff and water requirement, and the water balance elements were modeled to be balanced at the each control point of river network. The model was calibrated, verified and applied to the watershed for the Saemankeum tidal land reclamation development project. It showed that the results from the streamflow simulation at the Mankyung and Dongjin estuary were acceptable for the design of the Saemankeum estuary reservoir.

• Journal of Korean Society for Geospatial Information Science
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• v.11 no.1 s.24
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• pp.3-12
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• 2003

The main objective of this study is to extract the hydro-Parameter of the Tamjin River basin. A CIS is capable of extracting various hydrological factors from DEM. One of important tasks for hydrological analysis is the division of watershed. In this study, watershed itself and other geometric factors of watershed are extracted from DEM by using a CIS technique. The data of topographical map with scale of 1:25,000 and 1:250,000 in the Tamjin River basin is used for this study and it is converted to DEM date. Various forms of representation of spatial data are handled in main modules and a CRID module of ArcView. A GRID module is used on a stream in order to define watershed boundary. Based on the spatial analysis using those GIS technique, it would be possible to obtain the reasonable results of watershed characteristics. Also, the results show not only that GIS can aid watershed management, research and surveillance, but also that the geometric characteristics as parameters of watershed can be quantified more accurately and easily than conventional graphic methods. From the equations($Y=14632.87{\cdot}X^{-0.542444},\;Y=37014.1{\cdot}X^{-1.058808}$), it can be concluded that the optimal count of flow accumulation is 468 and cell size is 42m for spatial analysis by using GIS technique in Tamjin River basin.

• Korean Journal of Ichthyology
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• v.26 no.4
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• pp.249-258
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• 2014

To examine the taxonomic status of Acheilognathus sp. specimens from the Geum River, morphological and genetical characteristics of A. sp., A. yamatsutae and A. majusculus were investigated and compared in detail. Specimens of A. sp. could be distinguished from the other two species by the combination of some morphological characters such as nuptial color, vertebrae, gillrakers and etc. Males of A. sp. had red bands on the outer margin of dorsal and anal fins and a white band on the outer margin of ventral fin in breeding season. A. sp. had larger maximum body length and somewhat more vertebrae than A. yamatsutae, and had fewer gillrakers than A. majusculus. A. sp. appeared as a monophyletic group with A. majusculus and A. cyanostigma based on genetic analysis. In addition, it had even more close relationship with other congeners than A. yamatsutae. Therefore it is presumed that A. sp. from the Geum River may be a distinct species in genus Acheilognathus.