• Korean Journal of Ecology and Environment
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• v.44 no.3
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• pp.292-302
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• 2011

The Lake Sihwa watershed includes industrial, urban, and rural areas simultaneously. In this study, we analyzed the characteristics of dissolved organic matter (DOM) in spatial-temporal runoff patterns at representative sites having different land use in the watershed of Lake Sihwa. The result of synchronous and 3D-EEMs(3-Dimensional Excitation Emission Matrix Spectroscopy) analysis in 4TG (industrial area), fluorescence distribution and variation clearly appeared in the Fulvic-like fluorescence (FLF) and Humic-like fluorescence (HLF) regions along with the Protein-like fluorescence (PLF) region. A characteristic that Peak A (HLF) region fluorescence intensity did not decrease and the HLF region of fluorescence intensity and spatial-temporal changes clearly appeared during rainfall in AS (urban area). The results of fluorescence analysis in MS did not show great changes in PLF and FLF while showing that fluorescence intensity changes over time in the Terrestrial-like fluorescence (THLF) region increased greatly. In conclusion, our results showed significant differences in the runoff characteristics of DOM particularly in industrial, urban and rural area, and these differences should be considered for the efficient controlling of DOM in the watershed.

• Journal of Korea Water Resources Association
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• v.40 no.4
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• pp.299-311
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• 2007

Climatic abnormal phenomena involving El Nino and La Nina have been frequently reported in recent decades. The interannual climate variability represented by El Nino-Southern Oscillation (ENSO) is sometimes investigated to account for the climatic abnormal phenomena around the world. Although many hydroclimatologists have studied the impact of ENSO on regional precipitation and streamflow, however, there are still many difficulties in finding the dominant causal relationship between them. This relationship is very useful in making hydrological forecasting models for water resources management. In this study, the seasonal relationships between ENSO and hydrologic variables were investigated in Korea. As an ENSO indicator, Southern Oscillation Index (SOI) was used. Monthly precipitation, monthly mean temperature, and monthly dam inflow data were used after being transformed to the standardized normal index. Seasonal relationships between ENSO and hydrologic variables were investigated based on the exceedance probability and distribution of hydrologic variables conditioned on the ENSO episode. The results from the analysis of this study showed that the warm ENSO episode affects increases in precipitation and temperature, and the cold ENSO episode is related with decreases in precipitation and temperature in Korea. However, in some regions, the local relationships do not correspond with the general seasonal relationship.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.1
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• pp.43-52
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• 2006

Numerical model tests are done in order to evaluate impact zone of low salinity water on outer region of the developing Saemankeum reservoir. Also saline mixing processes are investigated f3r the inner reservoir with consideration of Mankyoung and Donjin riverine flood discharges when sea water is passing freely through gate. In these analyses 2-d ADCIRC, 3-d TIDED3D and CE-QUAL-ICM models are used. Through models tests, it is found that inner reservoir mixing process caused by inflow of outer sea water occurs gradually. It takes at least one month for complete mixing on Mankyoung part and 6 month on Dongjin part of the reservoir. When Sinsi or Garyeok gates are opened to control inner reservoir level, discharging velocities decrease exponentially from the gates, but show very strong currents of 0.5m/sec to the 10Km region apart. These results imply that hydrodynamic circulation and ecosystem of frontal region of the Saemankeum dike might be affected in amount by gate operations, since low saline inner waters are discharged periodically at ebb tide according to tidal level.

• Proceedings of KOSOMES biannual meeting
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• 2006.05a
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• pp.121-128
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• 2006

The results of COD researched on August of 2004 were 6.8 ppm in North Mokpo inner Bay, 4.4 ppm in front of YongSang Bank and 4.6 ppm in front of ShinAn Beach Hotel which is over III level Marine-Environmental Standard. The other five stations sea water quality of Mokpo inner bay were reached II-III level. Concentration of total nitrogen range from 1.23 ppm to 3.56 ppm and total phosphorous was range from 0.07 ppm to 0.12 ppm which were II-III level. This results show that the Mokpo inner bay is unsuitable for aquaculture and growth of fish and for use of marine resort, it can be only available for industrial and harbour use. In results of estimated point source flow into Mokpo inner bay, the occupation ratio from YoungSang river in total inflow of TN and TP were up to 49-89 % respectively. It is indicate that in order to improve the water quality of MokPo inner bay have to control the discharge from YoungSang river first of all, then control the discharge from North Harbour domestic wastewater treatment, InAm river and NamHae domestic wastewater treatment.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.9
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• pp.911-916
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• 2005

In this study, variations of water quality, sediment size and contaminant substances are analyzed at upstream and downstream in sewer systems in order to evaluate the characteristics of wastewater transformation by physico-chemical and biological reactions. The differences of DOC concentration between up and down stream showed the range of $-5.8{\sim}18.6$ from the result of continuous measurement at up and down stream. About 8.4% of DOC concentration was reduced and reduction rate was 2.3 mg/L/km. SS reduction rate was measured by 5.5 mg/L/km, 0.22 mg/L/min from upstream to downstream, which was twice than DOC reduction rate. When pollution load reduction was evaluated considering infiltration/inflow effect, DOC load was eliminated from 1,230 ka/d to 1,167 kg/d by physi-chemical and biological reaction in a sewer and 7.8% of the SS in upstream station was reduced under dry weather condition. The results showed that the characteristics of transformation process of wastewater in sewer should be considered for design and operation of wastewater treatment plant.

• Journal of Environmental Science International
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• v.16 no.4
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• pp.459-466
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• 2007

To analyze the water characteristics in the dry and wet seasons, the data for temperature, salinity, nutrients and $chl-{\alpha}$ were used, which were observed in the south coastal area of Korea during April to October 2000. At Yeosu in the south coast of Korea, the higher values of 35.0 psu in salinity were shown in March and April, the lower values of 23.0 psu in salinity were shown in August and September. The annual range of salinity was 12.0 psu. The total amount of precipitation in the wet season (July to October) was occupied 68% (about 846 mm) during 2000. The precipitation of the dry season (November to June) was occupied 32% (about 394 mm) in the year In the coastal area, the salinity variation is distinct in the period of July to October. Based on this result, we divided the season into two parts: the dry season during April to June and the wet season during July to October. Factor analysis was shown that temperature has strong negative relation and nutrients show positive relations in the dry season by the factor 1, which explains the total valiance of 50.6% at the surface water. In the wet season, salinity has negative relation and nutrients show positive relation by the factor 2, which explains the total variance of 33.5%. The bottom layer also showed similar to those of surface water in the results of factor analysis. These mean that nutrients become rich due to the freshwater inflow in the wet season. The low saline water is shown not only in the south coast but also in the overall region in the South Sea of Korea. It is suggested that the South Sea of Korea may call a ROFI (Region of Freshwater Influence) system in summer.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.2 no.2
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• pp.78-86
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• 1997

To clarify the phytoplankton blooms in Lake Shihwa after the construction of a dyke, a study on the environmental factors, the distribution of chlorophyll-a, phytoplankton standing stocks, dominant species and primary productivity was carried out in Lake Shihwa and adjacent coastal areas from October, 1995 to August, 1996. Lake Shihwa is brackish water with mixing of freshwater from tributaries and the remaining salt water at the bottom. The dense phytoplankton bloom of average value of 168.6 ${\mu}gChl-a\;l^{-1}$ have occurred throughout the year in Lake Shihwa which is eutrophicated by the large input of nutrients from inflowing 5 tributaries and Shihwa Industrial Complex. The major organisms of algal bloom in Lake Shihwa were diatoms, Cyclotella atomus, Nitzschia sp. and Chaetoceros sp. in autumn and winter, and dinoflagellate Prorocentrum minimum and Chrysophyceae in spring and summer. The autumn and winter diatom blooms were limited by the depletion of silicate in the lake. Diatom blooms have occurred in the coastal areas adjacent to Shihwa lake from winter to summer due to the inflow of nutrient rich-water from Lake Shihwa. The primary productivities in the Lake Shihwa ranged from 2,653 mgC $m^{-2}\;day^{-1}$ to 9,505 mgC $m^{-2}\;day^{-1}$ with an average of 3,972 mgC $m^{-2}\;day^{-1}$. However, most of the high primary production was limited to the shallow euphotic zone due to the inhibition of light penetration. The primary productivities during autumn and winter were limited by the depletion of silicate. Lack of photosynthesis and the decomposition of falling organic matter under the middle of water column accelerated the depletion of dissolved oxygen in the bottom layer.

• Journal of the Korean Society of Marine Environment & Safety
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• v.12 no.4 s.27
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• pp.273-283
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• 2006

The results of COD concentration on August of 2004 were 6.80 ppm in North Mokpo Inner Bay, 4.42 ppm un front of YongSang Bank and 4.60 ppm in front of ShinAn Beach Hotel which is over III level Marine Environmental Standard. The others researched five stations sea water quality of Mokpo inner bay are reached II-III level. The concentration of total nitrogen range from 1.23 ppm to 3.56 ppm and total phosphorous concentration was range from 0.07 ppm to 0.12 ppm which are to be II-III level. This results show that the Mokpo inner bay is unsuitable for aquaculture and for use of marine resort, it can be only avaliable for industrial and harbour port use. In this study, we researched 12 point source flow into Mokpo Inner bay. The rate from YoungSang river in total inflow of TN was up to 70-93 % and rate of TP was up to 31-91 % respectively. In this results, we have to control the discharge from YoungSang river first of all then control the discharge from North Harbour domestic wastewater treatment, InAm river and NamHae domestic wastewater treatment in order to improve the water quality of Mokpo Inner bay.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.2
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• pp.81-93
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• 2015

The comprehensive master plan in November 2010 on Saemangeum internal development has been released, and there is a need for complementary measures related to in-situ monitoring methods in order to acquire water temperature (T) and salinity (S) data. Thus, these data are monitored and analyzed by Korea Rural Community Corporation continuously. The purposes of current study are to evaluate the distributions of seasonal T and S, sigma-t, and stratification parameter and to compare annual stratification system in 2011 and 2012. To achieve these objectives, monthly vertical changes of T, S, and sigma-t, which are reproduced by a kriging technique, have been analyzed. In summer, the temperature difference between surface and bottom layers varies from 2 to $3^{\circ}C$, and the stratification of T is considerably weak. The stratification of S occurs abruptly within depth of EL. (-)5 to EL. (-)10 m. Therefore, stratification is induced by sudden increasing of water inflow amount due to a localized downpour during the rainy season, and these stratification processes are strongly influenced by inflowing a fresh water from watersheds in estuary environment.

• Korean Journal of Ecology and Environment
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• v.51 no.1
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• pp.29-39
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• 2018

Long-term variation of zooplankton community and species composition was studied from 2003 to 2014 in a deep reservoir, Lake Soyang, in monsoon climate region, Korea. In addition, we examined the correlation with environmental factors. Annual precipitation of watershed showed a large variation in the $705{\sim}1,779mm\;yr^{-1}$ and more than 70% of it was being concentrated from June to September. The water quality of Lake Soyang was shown a clearly seasonal variations and particularly turbid water flowing into the lake during rainy season was the most important environmental factors. Zooplankton community in Lake Soyang showed a significant difference before and after 2006. Zooplankton biomass has shown a large increase and also showed a change in the zooplankton community structure since 2006. The of zooplankton showed positive correlation with temperature and BOD, Chl. a, TP concentration. These results are considered that nutrient and organic matter contained in the turbid water influences the increase in zooplankton biomass and species composition. However, water quality was limited to account for the increase in biomass of zooplankton. For example, increase of small zooplankton density (rotifer; Keratella cochlearis, Polyarthra vulgaris) in spring which is dominated by diatoms (large size; Melosira, Synedra etc.) is considered as a bottom-up effect by the microbial loop. And increased density of crustaceans in autumn was considered a top-down effects by the relationship between predator and prey of microzooplankton and mesozooplankton. In other words the inflow of allochthonous organic matter during rainy season also affected to zooplankton food web in Lake Soyang. In conclusion, biomass, diversity and long-term variations of zooplankton in Lake Soyang were determined by physico-chemical factors but also it is considered that biological interactions is important.