• Journal of the Korean Society of Marine Environment & Safety
• /
• v.25 no.1
• /
• pp.89-95
• /
• 2019

Mooring observations of water temperature and salinity were conducted to investigate the effects of freshwater discharge patterns on the mouth of Nakdong River from April 2017 to March 2018. More than $500-1000m^3\;s^{-1}\;d^{-1}$ of freshwater was frequently discharged into the estuary throughout the rainy season, but less than $200m^3\;s^{-1}\;d^{-1}$ was discharged through the normal season. Sluice gates of the estuarine barrage operated depending on the tide level during spring tide, but they were constantly open during neap tide. Water temperature and salinity fluctuated regularly with intermittent discharges of freshwater, whereas they were stable while freshwater discharge was continuous. Mean salinity was 29 during the study period. Salinity exceeded the mean value in the normal season and rapidly recovered after a temporary reduction. In contrast, water with salinity below the mean value prevailed in the estuary for three months over the rainy season. These results indicate that water temperature and salinity were affected by the amount of freshwater discharge, as well as the frequency of discharge on a large scale and the time over which the freshwater discharge continued.

• Journal of Wetlands Research
• /
• v.16 no.1
• /
• pp.73-83
• /
• 2014

The government has recently carried out monitoring to attain a better understanding of the current situation and model for prediction of future events pertaining to water quality in the estuarine area of Yeongsan River. But many users have noted difficulties to understand and utilize the results because most monitoring and model data consist of figures and text. The aim of this study is to develop a GIS-based integrated information system to support the understanding of the current situation and prediction of future events about water quality in the estuarine area of Yeongsan River. To achieve this, a monitoring DB is assembled, a linkages model is defined, a GUI is composed, and the system development environment and system composition are defined. The monitoring data consisted of observation data from 2010 ~ 2012 in the estuarine area of Yeongsan River. The models used in the study are HSPF (Hydrological Simulation Program-Fortran) for simulation of the basin and EFDC (Environmental Fluid Dynamics Code) for simulation of the estuary and river. Ultimately, a GIS based system was presented for utilization and expression using monitoring and model data. The system supports prediction of the estuarine area ecological environment quantitatively and displays document type model simulation results in a map-based environment to enhance the user's spatial understanding. In future study, the system will be updated to include a decision making support system that is capable of handling estuary environment issues and support environmental assessment and development of related policies.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.19 no.2
• /
• pp.125-130
• /
• 2014

In order to evaluate the distributions of colloidal $^{210}Pb$ (half life = 22.2 years) and $^{210}Po$ (half life = 138 days) in subterranean estuary, we have measured $^{210}Pb$ and $^{210}Po$, for the first time, in the total dissolved (< $0.45{\mu}m$), true dissolved (<10 kDa), and colloidal ($10kDa-0.45{\mu}m$) phases in subterranean estuary of Hampyeong Bay in July 2010 and of Jeju Island in January 2011. The $^{210}Pb$ and $^{210}Po$ activities in groundwater were in the ranges of $0.21-2.52mBqL^{-1}$ and $0.12-2.07mBqL^{-1}$ for true dissolved phase and $0.10-1.71mBqL^{-1}$ and $0.03-0.97mBqL^{-1}$ for colloidal phase, respectively. The proportions of the colloidal phase to the total dissolved phase were $40{\pm}5%$ for $^{210}Pb$ and $28{\pm}5%$ for $^{210}Po$ in groundwater. This result indicates that colloids may play an important role in transporting trace elements through subterranean estuary into the coastal ocean.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.17 no.3
• /
• pp.149-159
• /
• 2012

To elucidate the species compositions of estuarine and inshore fauna and compare productivities between them, catch were collected by bag nets in the Han River estuary off Ganghwa Island and the inshore waters off Jangbong Island for 24 hours at the spring tide from March to December 2010. Community structures of nekton assemblages were different with area, month, taxonomic groups. Although the diversity of estuarine nekton assemblage was lower than that of inshore nekton assemblage, the productivity of nekton assemblage in estuary was higher than that in the inshore waters. Nekton assemblages were distributed according to habitat environment: the estuarine species, Coilia mystus, Chelon haematocheilus, Collichthys lucidus were prominent in the Han River estuary off Ganghwa Island, and marine species, Thryssa kammalensis, Sardinella zunasi, Portunus trituberculatus were prominent in the inshore waters off Jangbong Island. Palaemon gravieri, Exopalaemon carinicauda, Synechogobius hasta were inhabited in both waters. The health assessment of estuarine ecosystem based on scientific research will be contributed to the effective management of estuary with determination of order and direction in policy.

• Korean Journal of Ecology and Environment
• /
• v.45 no.2
• /
• pp.139-149
• /
• 2012

Four in situ incubation experiments were conducted in May, August and November 2009, as well as February 2010 to determine the seasonal primary productivity and the community structure of phytoplankton at the Seomjin estuary. The primary production of phytoplankton ranged from 9 to 3560 mgC $m^{-2}\;d^{-1}$. Primary productivity was the highest in the summer season (August), which was influenced by improved optical and temperature conditions of the water, as well as the supply of nutrients derived from its surrounding watershed. Particularly, the upper station (SJ-1, SJ-2) of Seom-jin estuary showed a higher productivity, as a result of inflow of input nutrients originated from the terrestrial source. The fucoxanthin, as an index pigment of diatoms showed the highest concentration (0.74~9.51 ${\mu}g\;L^{-1}$) at all stations, occupying 30~80% to total Chl a concentrations. The phytoplankton species composition determination, using a microscope showed similar results to the pigment analysis, which indicated diatom Skeletonema costatum, as the dominant species. The primary productivity in Seom-jin estuary indicates temporally and spatially large variation, according to different environmental conditions. Also, Skeletonema costatum has euryhaline features with relatively higher contribution.

• Journal of the Korean Geographical Society
• /
• v.42 no.3 s.120
• /
• pp.344-354
• /
• 2007

Estuarine wetlands for 33 watersheds in the Han River estuary were delineated on topographic maps from the 1910s, 1970s, and 2000s. Then, these data were used to address the issue of spatial distribution and temporal variation. Watershed characteristics such as drainage density, location, watershed size, slope, and elevation were identified for each watershed to determine the relationship between watershed characteristics and spatial distribution of estuarine wetlands. The analysis of estuarine wetlands indicated that wetlands in the estuary had declined gradually between the 1910s and the 1970s, although most wetlands were lost since the 1970s mainly caused by the large development projects related to urban expansion in metropolitan Seoul. The sediment composition and formation processes of the wetlands differed with watershed location; mud flats dominate in the lower part of the estuary, and relatively more sandy and emergent-plant wetlands occur near the main channel and tributaries of the Han River. Relatively more estuary wetlands occur in large watersheds, which have high slopes and low elevations. Estuarine wetlands have been lost dramatically in the densely populated watershed regions (i.e., Han River Seoul, Han River Goyang, West Han River), while relatively more wetlands have remained in undeveloped regions, including the Lower Imjin River and Lower Han River. In particular, anthropogenic disturbance has played an important role in the loss of wetland through the conversion of wetland into agricultural and developed land.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.19 no.1
• /
• pp.62-73
• /
• 2016

The variation of groundwater by wave, tide and precipitation conditions is closely related to the vegetation environment at the natural vegetation and sandy based beach, and it has a significant impact on the vegetation development and ground stabilization. In this study, the water temperature, electrical conductivity, and pressure were monitored at five observational stations normal to the Jinu-do(Island) shoreline of Nakdong river estuary from March 2012 to September 2014 (approximately 799 days) with the aim of measuring the variation in groundwater-table characteristics. The purpose of the study was to identify factors (tide, wave etc.) affecting groundwater-table variation using time series and correlation analysis, and to record spatial variations in the groundwater level and electrical conductivity as a result of storm events. The observational station in the intertidal zone was strongly affected by wave period and tide level. During the storm period, the groundwater-table and electrical conductivity were stabilized at the edge of sand dunes, vegetation, and areas of transition between freshwater and seawater.

• Proceedings of KOSOMES biannual meeting
• /
• 2003.05a
• /
• pp.191-200
• /
• 2003

Gunsan coastal area is one of region increasing pollution problems. One of the most important factors that cause eutrophication is nutrient materials containing nitrogen and phosphorus which stem from excreation of terrestial sources. At this study, the three-dimensional numerical hydrodynamic and ecosystem model, which was developed by Institute for Resources and Environment of Japan, were applied to analyze the processes affecting the eutrophication. The residual currents, which were obtained by integrating the simulated tidal currents over 1 tidal cycle, showed the presence of a typical. Density driven currents were generated westward at surface and eastward at the bottom in Geum estuary area where the fresh waters are flowing into. The ecosystem model was calibrated with the data surveyed in the field of the study area in annual average. The simulated results of DIN were fairly good coincided with the observed values within relative error of 32.39%. correlation coefficient(r) of 0.99. In the case of DIP, the simulated results were fairly good coincided with the observed values within relative error of 24.26%, correlation coefficient (r) of 0.82. The simulations of DIN and DIP concentrations were performed using ecosystem model under the conditions of 20 ∼ 80% pollution load reductions from pollution sources. In study area, concentration of DIN and DIP were reduced to 20∼80% and under 10% in case of the 80% reduction of the input loads from fresh water respectively. But pollution loads from sediment had hardly affected DIN and DIP concentration. For the environment management of coastal areas, in case of Kunsan area, the most important pollution sources affecting eutrophication phenomenon were found to be the input loads from fresh water.

• Journal of the Korean Geotechnical Society
• /
• v.22 no.12
• /
• pp.57-65
• /
• 2006

In the Nakdong River estuary soft and thick clay, which called Pusan clay, are deposited. Despite a number of great reclaimed projects that have been performed in the area, the consolidation settlement and time have been significantly underestimated due dominantly to sample disturbance, since the last decade. In order to resolve the underestmation, it was necessary to examine the compressibility characteristics through a systematic geotechnical investigation on the clay. In this study an advanced sampling technique was adopted on two sites chosen along the coastline, and then oedometer testing and geological investigation were performed for the undisturbed and reconstituted samples. As the results, the compressibility parameters of the clay were representatively determined, as well as their correlation. Particularly the effects of depositional environment on the physical indexes, level of structure, sample disturbance and compressibility parameters were analyzed for the clay.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.23 no.2
• /
• pp.167-181
• /
• 1995

An Ecocomplex is proposed for ecological design of the estuarine environment of Han River, which is designed upon an alternative mamagement concept of estuarine environment. The concept reveals interrelationships among estuary, delta region and urban inland with inputs/outputs and feedbacks among them. The Ecocomplex emphasizes an integration of wastewater treatment with aquaculture, agriculture and recreation, and carries out ecological treatment, recycling, and harvest processes. A module of wastewater treatment pond system is employed in the Ecocomplex, which treats a flow of 3,786 ㎥/day and is composed of a four-facultative-pond series. Treatment ponds stabilize wastewater discharged from the urban area, and concurrently produce algae for commercial or recreational fish farming. Effluent from treatment and fish ponds is reused for agricultural production. Through the waste-algae-fish-vegetable-recreation processes, wastewater from the urban settlement is recycled back to the urban ecosystem. This resource-conserving design approach can maintain a sustainable urban ecosystem, managing an estuarine environment more naturally, healthly, and economically.