• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.5
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• pp.882-895
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• 1997

Changes in the benthic communities have been studied to investigate the environmental effects before and after the construction of Shihwa Dike in the West coast of Korea. It is suggested that sequential changes in macrofaunal assemblages progressed in two sucressional directions. In the Shihwa lake under the influence of organic enrichment. First, the appearance of 'azoic tone' or 'grossly polluted zone' developed in the area of less than 6 m in depth resulted from the severe dissolved oxygen depletion due to the eutrophication from the increased organic loading. Second, the 'polluted zone' characterized by the proliferation of the opportunistic species in organically enriched area, was found in the vicinity of the industrial discharges and nearby fluvial inputs. This benthic community succession in the Shihwa lake seemed to be caused by the various ecological events such as an eutrophication in this organically enriched environment after construction of the dike and other physico-chemical parameters like salinity and dissolved oxygen in the bottom water, which may be influenced by the irregular surface water discharge and dilution by outer seawater inflow through the water gate of the dike. On the other hand, the benthic communities in the outside of the dike showed that the species richness was more than doubled and the abundance increased almost seven times more than that before the dike construction. This may be a typical characteristics of the initial phase in benthic eutrophication, suggesting that an increased organic input area may have been reponsible for this faunal change in the study area.

• Korean Journal of Plant Resources
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• v.20 no.1
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• pp.50-62
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• 2007

The flora of Banwol, Donghwa and Samhwa stream of the Sihwaho Phragmites communis wetland park was listed as 242 taxa; 72 families, 175 genera, 201 species, 38 varieties, 2 forms and 1 cultivar. Among these taxa, there were 92 taxa (38.0%) for the planted species, while 150 taxa (62.0%) for the native species. The halophytes were summarized as 13 taxa (5.4% among total 242 taxa); 5 families, 9 genera, 12 species, 1 variety. The naturalized plants were composed of 17 families, 41 genera, 45 species, 1 variety, totaling 46 taxa and naturalization index, urbanization index were 19.0%, 17.0%, respectively.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.3
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• pp.179-188
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• 2006

The purpose of this study is to quantitatively estimate the settling and erosional properties for cohesive sediments in Shihwa lake. Settling tests are conducted by multi-depth method using a specially designed 1.8 m tall settling column, and erosion tests are conducted with annular flume under the uniform bed condition. As result of settling tests, it is confirmed that the settling velocity of the cohesive sediments has the range of $0.002 for suspended sediments concentration of 0.1$0.19{\sim}0.55N/m^{2}$ for bed shear stress of $1.14{\sim}1.32g/cm^{3}$, and the erosion rate coefficient decreases with logarithmic function in a range of $18.4{\sim}3.9mg/cm^{2}{\cdot}hr$ with increase of bed shear stress.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.3
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• pp.262-267
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• 2006

For the concentration management in COD parameters, it requires the measurement and estimation of the COD pollutants load (hereinafter PL) in the watershed. The estimation method of the PL, however, is provided only based on the BOD parameters. The development of COD PL estimation schemes is expected to execute total PL management in coastal zone and needs to more observation and much time. This study provides COD PL estimation schemes using statistical information about ratio analysis with COD & BOD concentration of rivers and drainages of an industrial complex in Lake Shiwha and Incheon Coastal Zone watershed. The COD PL is computed with ease by multiplying the conversion factor, which is calculated as the sum of the average and 1 to 3 (safety factors) times standard deviation. The conversion factor of Lake Shihwa and Incheon Coastal Zone is estimated as 1.7, 2.3 and 2.9 with respect to the safety factor 1, 2, and 3, respectively.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.4
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• pp.265-271
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• 2014

We performed dilution experiments together with copepod added incubations to examine the influence of mesozooplankton on the grazing pressure of planktonic ciliates in Sihwa lake during summer when the abundances of phytoplankton and mesozooplankton increased considerably. Planktonic ciliates consumed 104% of primary production in a day on dilution experiments. However, the ciliates consumption on phytoplankton was reduced to 19% in copepod incubations with Acartia sinjiensis added. This was due to selective predation of A. sinjiensis on oligotrich ciliates ($>20{\mu}m$) which were major grazers on nano-phytoplankton. Our experiments show that grazing pressure of planktonic ciliates based on dilution experiments may be overestimated when the abundance of planktonic ciliates is strongly controlled by copepods. We postulate that the role of planktonic ciliates as grazers could diminish in Sihwa lake in spring and summer when abundance of copepods increase considerably. We suggest that the predation of mesozooplankton should be considered to better appraise the role of planktonic ciliates as grazers.

• Ocean and Polar Research
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• v.35 no.2
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• pp.69-83
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• 2013

Metal concentrations in creek water, sewer outlets and core sediments were analyzed to identify the potential origin of metal pollution and to evaluate the extent of metal pollution and potential toxicity of Lake Shihwa. Mean concentrations for dissolved metals in creek water and sewer outlets were 1.6~136 times higher than those in the surface seawater of Lake Shihwa. Metal concentrations in creek water from an industrial region were also higher than those from municipal and agricultural regions, indicating that the potential source of metal pollution in the study area might be mainly due to industrial activities. The vertical profiles of metals in core sediments showed an increasing trend toward the upper sediments. Extremely higher concentrations of metals were observed in the vicinity of Banweol industrial complex. The results of a geo-accumulation index indicated that Cu, Zn and Cd were highly polluted. By comparing the sediment quality guidelines such as TEL and PEL, six metals such as Cr, Ni, Cu, Zn, Cd and Pb levels in core sediments nearby industrial complex exceeded the PEL value. Mean PEL quotient (mPELQ) was used to integrate the estimate of potential toxicity for measured metals in the present study. Mean PELQs in core sediments from Lake Shihwa ranged from 0.2~2.3, indicating that benthic organisms nearby the industrial complex may have been adversely affected.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.2
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• pp.71-81
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• 2013

Trace metal concentration in sediment cores from the outer sea of Lake Shihwa were determined to study the vertical profiles of metal concentrations and to evaluate the levels of metal contamination. Sediment pollution assessment was carried out using enrichment factor (EF) and geo-accumulation index (Igeo). The mean concentration of metals were 58.8 mg/kg for Cr, 10.3 mg/kg for Co, 22.8 mg/kg for Ni, 18.1 mg/kg for Cu, 74.0 mg/kg for Zn, 6.75 mg/kg for As, 0.14 mg/kg for Cd, 27.4 mg/kg for Pb and 0.026 mg/kg for Hg, respectively. The mean EF values for Cu, Zn, As, Cd and Hg were greater than 1.5 in sediment cores, indicating that these metals in sediments are slightly enriched by anthropogenic activities. The geo-accumulation index (Igeo) suggested unpolluted status for metals of sediments collected from outer see of Lake Shihwa. Igeo values for Cu and Hg nearby LNG station (site C, D, E) ranged from 1 to 2, indicating moderately to unpolluted pollution status for those metals. Even if the higher concentrations of trace metals nearby LNG station were observed, there is significantly positive relationship between Al and trace metals. Thus, the sediment grain size plays an important roles in influencing the distribution of trace metals in sediment cores from the outer sea of Lake Shihwa. Based on the comparison with sediment quality guidelines such as threshold effect level and probable effect level in Korea, the concentration of metals in sediments from outer sea of Lake Shihwa are likely to result in no harmful effects on sediment-dwelling organisms.

• Journal of Korea Water Resources Association
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• v.36 no.2
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• pp.325-343
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• 2003

In this study, several types of rainfall time distribution of the probabilistic rainfall amount have been applied to the Sihwa Lake, located in Gyounggi Province, Korea and their runoff characteristics, obtained by the Hec-Hms program, according to the rainfall distribution types, were compared and analysed. And then, the influences of the above rainfall distribution types of the highest water level of the reservoir, computed through the reservoir flood routing, were analysed. The tidal variation was considered, performing the flood routing and, in addition, the new program, called “IWSEA”, which can compute the reservoir water level, was developed. To conclude, when the Mononobe type of the rainfall distribution was used, the largest inflow flood discharge into the reservoir was performed and the highest reservoir water level was obtained when the Pilgrim-Cordery type of the rainfall distribution was applied.

• Korean Journal of Environment and Ecology
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• v.19 no.3
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• pp.279-286
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• 2005

This study was conducted to analyze the changing pattern of the bird community after the construction of artificial wetland at Sihwah lake from may 2000 to January 2002. Total seventy seven bird species were recorded at Sihwa artificial wetland area during the survey. Number of the bird species and individuals were increased in second year than first survey year. Especially shorebirds and raptors were more increased than other groups. Long-term and continuous monitoring of bird community would be needed to clarify the reasons of increasing pattern of bird species and individuals in artificial wetlands of Sihwa lake. Until now, this area has been considered as suitable habitat for dabbling ducks than shore birds and has simple habitat environment consisting of open water surface and reed beds. Therefore, we suggest the follows for creation of diverse habitat types: 1) seasonal water-level manipulation 2) management of diverse aquatic plants and 3) creation of diverse land cover; sandy fields, gravelly fields, grasslands, etc.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.4
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• pp.276-284
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• 2000

Distributions of organic carbon (Co$_{org}$), organic nitrogen (N$_{org}$), and heavy metals (Zn, Pb, Cr, Cu, Mn) were investigated in Lake Shihwa sediments. Surface and core samples were collected in April and September, 1997 and March, 1998 for the study. The results show that these components contents are variable with sampling timeand station. In surface sediments, both Co$_{org}$ and N$_{org}$ have similar distribution pattern in which their high contents found in stations located near the land, indicating that the streams and industrial wastes seem to act as point sources. The C$_{org}$ contents are linearly related with those of heavy metals. It appears, therefore, that the distribution of heavy metals may be partly controlled by a complex interplay of biogenic, terrestial, and anthropogenic factors. The C/N ratios from three stations are in the range of 3-32, with an average of 13.2. Vertical profiles of heavy metals in sediment cores are similar to those of C$_{org}$ and N$_{org}$. Copper content of sediments is enriched compared to that of reported value before dike construction, but Zn and Mn are not deposited considerably. Especially, Pb content show less variable. Currently, anthropogenic effects of industrial complex may not reached to drainage gate area where heavy metal contents are comparable with those adjacent to coastal sediments.