• Journal of Korea Water Resources Association
• /
• v.43 no.6
• /
• pp.543-557
• /
• 2010

The effects of the selection for sediment transport equations and advection-diffusion equations according to different sediment transport modes on the modeling results of bed changes were analyzed using the CCHE2D and compared with field data in this paper. The most suitable sediment transport equation and sediment transport mode for advection-diffusion equation were suggested for the upstream approached channel of the Nakdong River Estuary Barrage. The bed changes simulated by the Engelund and Hansen formula were very small in the modeling case for the low and high flow discharges compared with the case of the Ackers and White formula. Also, the numerical modeling with the actual hydraulic event in 2002 presents that the bed change result with the bed load transport type for advection-diffusion equation was close to the field measurement more than the suspended load type.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.25 no.4
• /
• pp.265-281
• /
• 1992

The materials of this study consist of both specimens and survey records of the mollusks and crustaceans which were obtained from 30 collection sites in the Naktong Estuary during Aug.-Nov., 1991. The mollusks and crustaceans collected and identified in this study are 31 and 50 species, respectively. Of these two species of mollusks and six species of crustaceans were newly recored in this area. Including the previous records, the occurrence and distribution of 63 molluscan species and 138 crustacean species were compared in eight zones, before and after the construction of the Naktong Estuary Barrage. During this investigation, only a few species of mollusks occurred in the northern freshwaters off the Barrage. The habitats for the intertidal species were greatly destructed along the eastern part of the UIsuk Is. and the riverside of Tadaep'o where the bank was recently constructed. The commercial bivalves including Corbicula fluminea and Ruditapes Philkippinarum were greatly decreased in number in all the eatuarine waters. A freshwater crab, Eriocheir japonicus, seems to be extinguished in the Naktong River and its neighbouring streams.

• Journal of Korea Water Resources Association
• /
• v.48 no.1
• /
• pp.45-55
• /
• 2015

In this study, when seawall or harbor gate is installed for coastal disaster prevention, a two-dimensional water analysis in the bay is carried out to consider the flood amount of river inflow and effect of harbor gate. The Yeongsan river and the port Mokpo area are selcected for the study region. Then, by analyzing the hydraulic characteristics of flood flow of the Yeongsan river, we analysed the compatibility of the results in the two-dimensional hydrodynamic model. A tw-odimensional water analysis were conducted for the four cases considering whether a harbor gate is installed or not, and whether the inland water boundary condition is considered or not, also with open sea boundary condition. The results of the two-dimensional water analysis shows that water level change near the port Mokpo area is mainly caused by the discharge of the estuary barrage of the Yeongsan river because the harbor gate was installed. In addition, it is revealed that the volume of reservoir created by the harbor gate and the estuary barrage is too much small compared to the volume of the discharge from the Yeongsan river. Therefore, when the harbor gate is installed in the open sea, we concluded that a flexible management between the harbor gate and the estuary barrage of the Yeongsan river is required. A initial water level of the bay and outflow from the harbor gate are proposed for disaster prevention in the coastal area of port Mokpo.

• 한국신재생에너지학회:학술대회논문집
• /
• 2006.11a
• /
• pp.134-137
• /
• 2006

Tidal power can use conventional technology to extract energy from the tides. It is usually best deployed in areas where there i s a high tical range which includes Western and Southern coastal areas in Korea. However, to extract tical energy, a barrage across an estuary or a bay is to be constructed that is now very hard due to severe environmental impact on local estuary. The recent technology of application of tidal stream provides a new window to extract power minimizing the adverse environmental impact Tidal stream technology which directly exploits these currents is relatively new but is presently generating considerable interest Turbine rotors can be used to extract energy from the flows. Prototype devices currently on test in the UK include the 300kW SeaFlow turbine. In this paper, the recent technology and research on ocean tical stream power are addressed

• Journal of Korean Port Research
• /
• v.5 no.2
• /
• pp.65-75
• /
• 1991

Tidal current and water level change in coastal waters are formulated in terms of mathematical models. A systematic discussion of the derivation of a set of governing equations, expressing conservation of mass and momentum is presented. A simplification is introduced by integrating all variables and equations over the total water depth, the Solution of the formulated problem is achieved by using the finite difference method(FDM). The applied study area is taken from Mokpo harbor and its adjacent coastal water which have significant hydrographical changes due to the construction of the estuary barrage and land reclamation work of estuary barren. Some comparisons with the observed current and water level changes the numerical solutions are found to be considerably fit well for the recent coastal water motion.

• Korean Journal of Microbiology
• /
• v.32 no.3
• /
• pp.238-244
• /
• 1994

To investigate the bacterial potentials for utilizing dissolved organic matter in highly eutrophic estuary, the annual fluctuations of microbiological and physicochemical environmental parameters were analyzed in Naktong River Estuary. Total bacterial number ranged from 0.33 to $2.09{\times}10^7$ cells/ml, and correlated with the heterotrophic bacterial numbers in more eutrophic sites, especially. Bacterial biovolume and biomass varied between 0.064 and 0.156 2.09${\mu}m^3$/cell, 0.163 and 1.036 ${\mu}g$-C/ml, respectively. Bacterial secondary productivity ranged from 0.24 to 60.86 ${\mu}g$-C/l/h, and showed high correlations with the environmental parameters of pollution indicator. The seasonal variation pattern of bacterial productivity in freshwater sites was high in winter and low in summer, which was interpreted as the results of pollution loads varied with the amount of rainfall. In seawater site, the pattern was different from those of freshwater sites; high in summer and low in winter. In this site, the values of bacterial productivity showed positive correaltions with chlorophyll a, heterotrophic bacterial number, and temperature (r>0.5, p<0.05). These results suggested that the main source of organic matter which influences the bacterial productivity may be allochthonous materials in the upper freshwater zone of Naktong River Barrage, and autochthonous algal excretory products in the lower seawater zone of Naktong River Barrage.

• Korean Journal of Ecology and Environment
• /
• v.46 no.2
• /
• pp.175-184
• /
• 2013

Organic carbon and total nitrogen stable isotope ratios of suspended materials were determined at 3 stations (from Mongtan Bridge to Youngsan river estuary barrage) (n=6, each) from November 2008 to August 2009, in order to understand the origin of particulate organic matter at the Estuary of Youngsan River. Allochthonous organic matter, ammonia-N and silicate were increased after heavy rain (in August). Carbon isotope ratios were significantly different between stations in November and August, and it was possible to determine the origin of organic matter. The heavier nitrogen isotope ratios, as well as higher phosphate concentrations, were found in November than other sampling times. Livestock wastewater and farmland input was likely the main causes of these high values. In addition, YS3 station, the nearest site to estuary barrage, appears to be affected by a substantial amount of livestock wastewater and farmland input, considering that nitrogen isotope ratios were heavier than those at the upper sites. These results suggest that the analysis of stable isotope ratios is a simple but useful tool for the determination of organic matter origin in aquatic environments.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.16 no.2
• /
• pp.70-80
• /
• 2011

Estuarine ecosystem responds sensitively to natural and anthropogenic perturbations. lt is necessary to identify the direction of the change when the perturbation occurs as well as to understand the structure and functioning of estuarine ecosystem for a proper management of the area. In this study, the estuarine habitats were classified into different ecological districts so as to the switch from one district to another district could be related to the environmental change due to the perturbations. Total 16 ecological districts was defined according to the presence of barrage, salinity and vegetation characteristics. The defined ecological districts were applied to small estuaries in Goseong bay, south sea of Korea (Baedun, Guman, Maam, Goseong) to distinguish different regions which might have characteristic bottom topography, inclinations of river bottom, sediment characteristics, salinity structure and area of vegetation. Total 7 out of 16 ecological district was identified in this region; NFB (natural, fresh, bare), NHB (natural, high salinity, bare), NLV (natural, low salinity, vegetated) in natural (without barrage) estuaries and CFB (closed, fresh, bare), CFV( closed, fresh vegetated), CLV (closed, low salinity, vegetated), CHB (closed, high salinity, bare) in closed (with barrage) estuary. A comparison of environmental factors and biota between CHB and CLV demonstrated the effect of barrage on estuarine ecosystem. The height and sediment characteristics of CHB and CLV were similar but the average salinity was lower in CLV than in CHB due to the barrage, which produced favorable condition for the Phragmites australis in CLV. Information regarding the ecological districts in various sizes and location could be useful for predicting the ecosystem change due to natural and anthropogenic perturbations and for preparing management actions.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.34 no.5
• /
• pp.457-469
• /
• 2016

Nakdong river barrage was affected by artificial interference such as construction of port, industrial complex and estuary barrage. This change in Nadong river lead to environmental changes and affected the ability of barrier islands. Therefore, it is decided that the observation of changes in the Nakdong river estuary is very important. In this paper, the topographic change of the Nakdong river barrage observe based on Landsat TM, ETM+ images from 1984 to 2015. In addition, this study tried to conduct a comparative analysis on the area for change of sandy sediment according to tide level. This results could estimate height and volume about sandy sediment accumulated on the lower sand dune. Also, these results are expected to be the basis for prediction of the changing topography of the sand dune. The area of the average change in region 1,2,3 was calculated as 3,015m², 167,550m², 14,596m². This result is expected to be very useful for the continuous observation for sediment changes of Nakdong river.

• Journal of Korean Port Research
• /
• v.13 no.1
• /
• pp.133-146
• /
• 1999

Mokpo coastal area is connected to the adjacent a long river and two large basins. It is essential for port planning coastal zone management and environmental impact study to analyze the data related to the ship operation and variation of current and water quality due to the development of water area including dredging reclamation and estuary barrage. The Yongsan river estuary weir and Yongam-Kumho basins discharge much of water through water gates for the purpose of flood control and prohibit salt intrusion at the inland fresh water area. To meet this purpose discharge through the gates have been done at the period of maximum water level difference between inner river and sea level. This discharged water may cause the changes of current pattern and other environmental influences in the vicinity and inner area of semi-closed Mokpo harbor. In this study ADI method is applied to the governing equation for the analysis of the changes on current pattern due to discharged water. As the results of this study it is known that the discharging operation causes many changes including the increase of current velocity at the front water area at piers approaching passage and anchorages. Discussion made on the point of problems such as restricted maneuverability and the safety of morred vessels at pier and anchorage. To minimize this influence the linked gate operation discharging warning system and laternative mooring system are recommended.