• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.4
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• pp.1-20
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• 1986

Physical, chemical and biological surveys on Nakdong River estuary were made from October, 1985 to September, 1986. 1. For all the seasons except summer, the sea surface temperature in northwest area of the line which linked from Seo Island to Jisim Island was I-2$^{\circ}$C lower than in southeast area, but in summer the sea surface temperature in northwest area was I-2$^{\circ}$C higher than in southeast area. On the contrary, bottom temperature of coastal area was 1$^{\circ}$C higher than that of oceanic area except winter. 2. Surface salinity in summer and fall has minimum value of 1. 9%0 and maximum value of 32.9%0. This large variation was caused by the runoff of the Nakdong River. Effect of less saline Nakdong River water in northwest area of the line which linked from Seo Island to Jisim Island was greater than in southeast area. A strong current rip always formed near this line. 3. The yellowish-green colored zone was observed in the Nakdong River estuary throughout the year by influence of river discharge. The characteristics of the water quality in the zone have shown that the water color was grade 7 by the Forel water-color meter, transparency was less than 4 m, and concentration of suspended solids was more than 5 mg/1. This water body was in the state of eutrophication in terms of chlorophyll-a and inorganic nitrogen concentration during summer season. 4. During the study period, total 276 taxa were identified. Most of them were diatoms and dinoflagellates which consisted of 97.5%. The component ratio of the above two groups was 84.4% and 13.1 % respectively. Diatoms were plentiful in December and dinoflagellates in July. Dominant species were Nitzschia seriata in October, Thalassiosira rotula in December, Skeletoncma costatum in April, and Nitzschia longissima in July. 5. A total of 47 zooplankton taxa was identified from the samples collected. Copepods were numerically the most important components of zooplankton communities in the study area. The domir:ant copepod species were Paracalanus parvus, Acartia clausi and Temora turbinata. Noctiluca scintillans was the next important component. The other zooplankton with minor abundance were Cladocera. Sagitta spp., Cnidaria, Mysidacea, Lucifer spp. and Amphipoda. 6. During the study period, fishes from 47 families and 87 species were sampled in th~ study area. The four most abundant fish species were Rep~mucen//'s valencicnnei, Leiognathus n~cha!is, Amblychaeturicllthys hexanema and Sardirel/a zun:zsi. The fish species of the secondary importance in abundance were Cynoglossus joyneri, Sillago sihama, Engra~lis japonicus, Encdrias nebulos'l, Acanthogobius flavimanus, Trichiurus lepturus, LiParis tanai/ai, Cynagloss//'s interruptus, Aj)ogon line:z!us, Thrissz la 1l.'1la!ensis, and Limanda yokohamac.

• Korean Journal of Environment and Ecology
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• v.22 no.6
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• pp.625-631
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• 2008

We used the visitation aspect of dabbling ducks(Anas spp.) to investigate the estuarine ecosystem of Nakdong River and to compare the data collected during two periods: trom May, 1989 to April 1993 and from May, 2002 to April 2006. Over for the 8 years of field surveys, 356,110 individuals from 11 species of dabbling ducks(Anas spp.) were observed in the Nakdong estuary. In the early 1990s, the average number of species gradually increased from October through November, whereas the highest numbers of species were recorded in October during the second survey period. The average number of individuals recorded during the second period was 2-3 times higher than that observed in the 1990s. Statistical analysis using a t-test indicated that the number of individuals showed significant difference at 5% level between November and February in both the early 1990s and the mid-2000s. During the winter, dabbling ducks select both estuarine wetlands as resting sites and rice paddy as feeding sites. More wintering migrants including ducks would visit to Nakdong river if we provide with enough rice paddy near the estuary. The farmland around Nakdong estuary is used by dabbling ducks as a habitat, we hope it must be conserved thoroughly. CRP(crop reserve program), implemented by the local government of Kangseo-gu, Busan City is effective in conserving rice paddy; therefore, the CRP program need to be continuously applied in the Nakdong river basin.

• Journal of Korea Water Resources Association
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• v.55 no.5
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• pp.383-392
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• 2022

The restoration of the Nakdong River estuary is one of the most important projects of the Ministry of Environment, Republic of Korea. A real-scale experiment of gate operation was executed from 2019 to 2020, and a pilot operation was performed in 2021. The gate of Nakdong River Estuary Barrier (NEB) is supposed to be continuously opened based on the experiment results. Many critical decisions should be made immediately during the experiment based on the real-time measured data and numerical analysis considering the seawater inflows. The decision-making sequence was made systematically with the accurate estimation of seawater inflow. The estimation of seawater inflow is the main research objective and the equations of seawater inflow were developed, reflecting the structural characteristics of NEB. The inflow equations were developed in two forms, overflow and underflow. ADCP (Acoustic Doppler Current Profiler) was used to measure seawater inflow, check the accuracy of the developed equations, and derive the flow coefficient. The comparison error of the developed equations was about 3% compared to the measured data.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.4
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• pp.296-301
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• 1993

A hydrodynamic solution for the lateral spreading of a river plume which was developed by assuming a Gaussian distribution of density difference between a turbulent jet river plume and ambient salt water is verified by the field data in the Nakdong river plume. Effect of the river plume on the transport of fine-grained suspended sediment at the Nakdong Estuary is also examined. The analysis of fold data showed a reasonably good correspondence with the theoretical solution adopted in this work Therefore, the hydrodynamic solution can be used as a useful tool in dealing with the lateral spreading of a river plume. The density stratification due to the existence of a river plume seems to cause a retarded settling of the suspended sediments in the water column. and thus a farther transport of the fine sediment is expected than in the normal steady flow.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2020.10a
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• pp.168-168
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• 2020

• Journal of Wetlands Research
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• v.16 no.3
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• pp.355-362
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• 2014

Changes of soil properties due to sedimentation and erosion in the river estuary may lead changes in environmental factors that affect plant growth and distribution, Then habitats in the river estuary that provide various ecological functions can also be influenced. Topsoil samples were analyzed in order to understand the soil properties of important barrier islands and habitat types in the Nakdong river estuary. The samples were obtained from Phragmites communis and Scirpus planiculmis habitats, the tidal flats in the southern area of Eulsukdo, and in Mangeummerydeung, Baekhapdeung, and Doyodeung. Analyses results showed that bulk density, pH, organic matter content and total nitrogen concentration which were directly or indirectly affected by vegetation showed significant difference (p<0.05) with habitat types but no differences in water content and oxidation reduction potential which could be affected by soil texture and showed significant difference among barrier islands. Results suggested that soil properties on barrier islands in the Nakdong river estuary were influenced first by geomorphic changes due to sedimentation and erosion, and then by the presence or type of vegetation. A range of physical and chemical properties were analyzed; soil water content and bulk density (physical properties), and organic content and pH (chemical properties) were correlated with seven other soil properties, at a level of significance higher than 90%. These aspects played an important role in determining overall soil properties in the studied area.

• Korean Journal of Ichthyology
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• v.27 no.2
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• pp.104-115
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• 2015

The species composition of larval fish assemblages in the Nakdong River estuary, Korea, was determined using monthly samples collected between September 2010 and August 2011 at two stations. A total of forty three larval species were collected during the study. Among forty three taxa of fish larvae, summer gobies, Clupea pallasii, Engraulis japonicus, spring gobies, Konosirus punctatus, winter gobies, Sardinops melanostictus, Coilia nasus were dominant taxa, and these eight taxa accounted for 95.0% in the total number of individuals. Species composition and abundance varied greatly spatio-temprally showing the peak abundances of fish larvae in August 2011, and a few fish larvae were occurred in November 2010. Cluster analysis based on the number of individuals of fish larvae showed that 21 month-station sampling units were classified into five groups at the similarity level of 50%, and the results of ANOSIM and SIMPER analysis revealed significant differences in community structure among five groups.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.4
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• pp.1-7
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• 2007

Using field observations, this study estimated the total weight and types of marine debris along the coast of Jinu Island in the Nakdong River Estuary after typhoons Usagi and Nari had passed. A numerical wave model was used to calculate the spatial wave height distribution at the time of the typhoons' passage. This study found that the total accumulation rate of marine debris deposited on the coast after the two typhoons had passed was about $5,769.86\;kg/km^2/day$ at this site, which was 14.42 times as high as that in normal weather. The wave height distribution in the sea off Jinu Island, based on numerical modeling, was $4.1{\sim}3.5\;m$, which was 1.0-2.5 times greater than for the case of other islands. Therefore, it is likely that the concentration of wave energy led to the deposition of marine debris.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.6
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• pp.766-772
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• 2016

The composition of the diet of juvenile barbel steeds, Hemibarbus labeo was studied using 67 specimens collected in August, 2004 from the surf zone of the Nakdong river estuary. The fish examined ranged from 5.1 to 9.7 cm in standard length (SL). Hemibarbus labeo was found to be carnivorous and consumed mainly amphipods, with teleosts, polychaetes, and shrimps following. They showed size-related changes in diet. Small individuals (< 6.4 cm SL) mainly consumed amphipods. As fish size increased, the portion of amphipods consumed decreased, while a reverse trend was evident for teleosts. It was also observed that Hemibarbus labeo consumed more amphipods and polychaetes during the day, while fish served as their main prey during the night.

• Ocean and Polar Research
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• v.27 no.2
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• pp.135-148
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• 2005

Macrobeilthic fauna were collected using a van Veen grab $(0.1m^2)$ to investigate the spatial characteristics of the macrobenthos community at 28 stations near the Nakdong River estuary, Southeast Korea, in September 2001. A total of 203 species were sampled with a mean density of $1,554 ind./m^2$ and a biomass of $252.3 gWWt/m^2$. Annelids were the dominant faunal group in terms of species and density, with 68 species and a mean density of $1,031ind./m^2$, which comprised 33.5% and 66.3% of the total benthic animals, respectively. Based on density, three Polychaetes were dominant Tharyx sp· $(420ind./m^2)$, Lumbrineris longifolia $(143ind./m^2)$, and Sternaspis scutata $(118ind./m^2)$, along with a bivalve Theora fragilis $(129 ind./m^2)$. On cluster analysis, the benthic community was classified into four groups based on the species composition: Group-1 occurred in disturbed areas, Group-II in coastal regions, Group-III in central mariculture grounds, and Group-IV offshore. Environmental factors (mean gain size, organic carbon, and depth) were primarily correlated with the macrobenthos community structure. A benthic pollution assessment based on the macrobenthos community structure showed that Group-I and Group-II were located in a coastal area that had been severely disturbed by construction of Busan new port and various pollutants, Group-III was gradually polluted, while offshore Group-IV was the most stable.