• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.2
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• pp.127-135
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• 1999

Grain-size distribution and accumulation rate of surface sediments on the tidal flats in Hampyong Bay, southwestern coast of Korea, were investigated in a sequential interval of 2 months for the period of 27 months (1994. 10~1996. 12). Seasonal variation of grain-size distribution is prevalent on the Shimock tidal flat in the southern side of the innerbay, rather than the Anarc tidal flat in the northern side around the baymouth. This variation, in particular, more distinctive in the areas around the both high and low tide water levels. The Shimock tidal flat shows typical seasonal variation of sedimentary processes, expected under monsoonal climate. Deposition of tine-grained sediments in summer dominates over erosion in winter, resulting in an annual accumulation rate of 3.7 mm/yr. In contrast, sedimentary processes on the Anarc tidal flat is abnormal that have experienced slight deposition of fine-grained sediments in the winter and severe erosion in the summer time, showing a negative annual accumulation rate of -49.6 mm/yr. Erosional processes in this area is interpreted due mainly to change of strength and direction of tidal currents, caused by the artificial construction of dyke for reclamation in the mid-tidal flat. As a result, It is immoderate to conclude whether sedimentary processes of Hampyong Bay is erosional or depositional at current situation. Further studies on sedimentary budget at the entrance to the bay are needed.

• The Korean Journal of Ecology
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• v.20 no.4
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• pp.275-283
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• 1997

Vertical and temporal characteristics of desalinized reclaimed soil were analyzed from reclaimed coastal land on the western coast of Korea. Of the vertical changes during desalting, pH valuse were the lowest at the topsoil without regard to reclaimation time. The content of C1 were designated as the early period (the first 2-4 years) which decreased exponentially and the later period(the last 5-7 years) which was almost constant, from top to down. In temporal changes of the soil attributes, pH values increased for 5 years and decreased at 6 year after reclamation. Chlorine leaches more rapidly than Na does, K and Ca are constant but Mg increases as time elapsed after reclamation. Sometimes the content of Ca and K in the reclaimed soil are of higher concentration than that of the seawater after reclamation. During desallinization as exemplified by decreasing EC of the soil, Cl and Na are rapidly leached, but K, Ca and Mg are somewhat enhanced. The ration of Na/Cl in the soil equals 1 when the EC registers 5 mmho and then increases dramatically as the EC decreases. Rapid leaching of $Cl^{-}$ elicits an increasing pH valus. The electrostatic balance of the soil is achived by replacement of $Cl^{-}$ with $OH^{-}$ until stationary or until a decreasing pH value is reached again.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.1
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• pp.212-225
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• 2015

In order to preserve the quality of fresh water in the artificial lake after the reclamation of an intertidal flat at the mouth of a river, we suggest two novel methods of water purification by using tidal potential energy and an enclosed permeable embankment called an utsuro (Akai et al., 1990) in the reclaimed region. One method uses an inflatable bag on the seabed within an utsuro, while the other uses a moored floating barge out of a dyke. Each case employs a subsea pipe to allow flow between the inside and outside of the utsuro. The change in water level in the utsuro, which is pushed through the pipe by the potential energy outside, caused circulation in the artificial lake. In this paper, we analyzed the inflatable bag and floating barge motion as well as the pipe flow characteristics and drafts as given by a harmonic sea level, and compared the theoretical value with an experimental value with a simple small model basin. The numerical calculation based on theory showed good agreement with experimental values.

• Ocean and Polar Research
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• v.28 no.3
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• pp.353-360
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• 2006

A 33-km long sea dyke is being constructed in the Saemangeum area mid-west of Korea to reclaim a surface area of 40,100 ha which includes well-developed tidal flat and two river estuaries. The northern part of the dyke was closed on 10 June 2003, while the southern part was recently closed on 21 April 2006 by plugging two opening gaps of 2.7 km in length. In this study, firstly we review the outlines of key national projects which described marine environments in the Saemangeum area and secondly we present a summary of remarkable changes in marine environments after the closure of the northern dyke, based on marine environmental data collected during 2002-2005. Details in each discipline of the marine environments are presented both in other papers of this special volume and in a series of annual reports of the Ministry of Maritime Affairs and fisheries.

• Journal of the Korean earth science society
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• v.23 no.7
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• pp.565-574
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• 2002

Based on previous investigations of aerial photographs and topographical surveys, this study focuses on the sedimentologic features of the Daebudo area including sedimentation processes, sedimentary facies and hydrologic conditions of the erosional coast. A total of 137 surface sediments and one core (by hand auger) sediment were obtained to interpret the depositional environment of the erosional coast in the macro-tidal coast. Surface sediments are distributed from sandy gravel (sG) to silt (Z). Textural parameters are characterized not only by coarse, poorly sorted, positive skewed and multi-modal distribution in the supra-tidal flat, but also finer, relatively well-sorted, symmetric distribution in the intertidal flat. According to the C/M diagram, sediment transport modes of study area are characterized by the mixed mode of suspension and bedload in the upper-, middle-tidal flat and by uniform suspension in the lower-tidal flat due to tidal effect. Vertical sediment distribution of the core, collected near shoreline, shows coarsening-upward, poorly sorted pattern by the input of detritus resulting from coastal erosion. Considering the sedimentological features of the study area, it appears to be composed of a coastal zone changed by not only artificial reclamation, but also by natural processes such as strong wave action due to typhoons and storms during high water level and long/short-term sea level rising. As a result, tide-dominated erosional coasts show that the shore is affected by local, temporal and hydrological conditions near high tide level and that the intertidal flat is represented by a general tide-dominated sedimentary environment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.4
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• pp.402-408
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• 2003

A quantitative method was suggested for estimating damages in fishery production due to the diffusion and deposition of suspended silt and clay by various construction processes in tidal flat fishing grounds. Marine populations are maintained through the process of spawning, growth, recruitment, natural death and death by fishing each year. All of the year classes of the population in a fishery ground could be affected when damages occur by human activities such as land filling or reclamation. The propose of this study is to calculate damages in terms of fishery production using a quantitative population dynamic method. If the maximum age in the population is $X_\lambda,$ the starting year of damage is $t_s,$ and the ending year of damage is $t_e,$ the number of year classes damaged is $t_{s-n\lambda}-t_e,$ Many year classes present in the year $t_s,$ and so if damages occur, they Influence all the year classes which are present in the population. Damaged year classes in year $t_e$ would still be in the population until the year $t_{e+n\lambda}$, where $n_{\lambda}$ is the oldest age class. If the expected yield of a year class is constant, the total yield from year classes in the fishing ground during the construction periods can be calculated as follows: $Y_\Phi=[(t_e-t_s+1)+n_c]{\cdot}Y_E+\sum\limits^{n_\lambda-n_c}_{l=1}\;\sum\limits^{n_\lambda-n_c}_{l=i}\;Y_{n_c+i}$ This method was applied for damage estimation in the production of Ruditapes philippinarum in a tidal flat fishing ground.

• Journal of the Korean Geographical Society
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• v.32 no.4
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• pp.463-478
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• 1997

This paper examines the impact of large-scale tidal flat reclamations on environment by analyzing land use change, ocean cultivation, water quality, sea biota and climate in Shiwha, Sosan and Saemankeum districts. The data used in this paper include Landsat TM images and documents related to population, industry, water quality, sea biota and climate at the time of the pre- and post-reclamation. Many times of field reclamations contribute to the creatation of newly available land for urban and industrial development, but cause environmental degradation significantly. The increase of pollution load and the change of coastal ecology, also cause some changes of climatic element such as relative humidity. As tidal flats were reduced, the area of ocean cultivation and the population of fishing industries were decreased. Conceming the sustainable development. it is necessary to carry out a careful environmental impact assessment accumulating monitoring environmental data continuously by using GIS techniques.

• Journal of the Korean Geographical Society
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• v.38 no.4
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• pp.535-561
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• 2003

The Kyodong Island on the Yellow Sea has experienced dramatic transformations in the process of massive reclamations of tidal flats. Consisting originally of detached several islets, Kyodong became an integrated island country with the establishment of sea dikes across the salt marshes. The coastal plaines passed through four distinct stages of development. During the nascent period from the Early States to the Koryo Dynasty, strategic considerations led up to the establishment of causeways and garrison farms as well as private land plots. The relocation of regional headquarters of the navy into the island made the reclamation of tidal flats a systematic project during the period of Chosun Korea. The implantation of a large-scale estate by Japanese capitalists was the most characteristic feature of this region's geography during the colonial period. Present-day Kyodong displays various agrarian landscapes of standardized land plots, reinforced sea dikes, and automated agricultural machinery. Throughout the periods irrigation systems have sustained the panoramic transformation of the agricultural geographies of the Kyodong Island. The local people afflicted by a chronic deficiency of water came up with ingenuous irrigation systems such as springs, paddy reservoirs, reservoirs, tanks, artesian wells, and pump stations.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.4
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• pp.409-415
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• 1999

To evaluate the purification capacity of pollutants (COD, $PO_4^{3-}-p$, $NO_3^{-}-N$, Cu, Cd, Pb) in the three tidal flats, Eueunri, Gyewhado, Chunjangdae, the experiments were carried out with the batch reactor equipped with artifical tidal flats. Eueunri tidal flat was $98.8\%$ content of silt and clay and Chungjangdae was $97.84\%$ content of sand. The organic matters (I.L., $COD_{sed}$, POC) in Eueunri tidal flat were 2$\~$8 times higher than other tidal flats. The purification capacity of COD was 0.75 kg/ha/12 hr in Eueunri, 0.60 kg/ha/12 hr in Gyewhado and 0.55 kg/ha/12 hr in Chunjangdae. The mean purification capacity of COD in three tidal flats was 1.27 kg/ha/day. The calculated purification capacity of COD was 25.4 ton/day in the disappeared tidal flat areas (20,000 ha) of the Saemangeum reclamation. The purification capacity of phosphorus was 0.21 kg/ha/12 hr in Gyewhado, 0.39 kg/ha/12 hr in Eueunri and 0.22 kg/ha/12hr in Chunjangdae. The nitrate was 0.53, 0.74 and 0.43kg/ha/12hr, respectively. The purification capacity of heavy metals (Cu, Cd, Pb) were 88.9g/ha/12hr, 11.0g/ha/12hr, 1.7g/ha/12hr in Gyewhado, 89.1g/ha/12hr, 18.0g/ha/12hr, 2.6g/ha/12hr in Eueunri and 55.3g/ha/12hr, 18.0g/ha/12hr, 2.1g/ha/12hr in Chunjangdae, respectively. Accordingly, the purification capacity of pollutants in Eueunri tidal flat with high contents of organic matter were higher than other tidal flats. So, the purification capacity of pollutants were affected by physical and/or chemical characteristics of tidal flats.

• Journal of the Korean Association of Geographic Information Studies
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• v.8 no.1
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• pp.13-22
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• 2005

This paper classifies the topography of the Saemangeum Tidal flats based on Landsat TM satellite images by unsupervised ISODATA method, and analysis of the spatiotemporal changes of the classified shapes. The sedimental topography represents various properties according to the Saemangeum Tidal Embankment progress. We well proceed this study of the sedimental changes and distributions. By specifying the topographic characteristics of inner sea areas respectively, the investigation on the case study area according to the changes of the tidal will be useful in the establishment of land reclamation plan and the land use of the reclaimed area. In addition, the estuary image can be divided into tidal flats and sea surfaces using the band 4, also the detailed topography using the band 5, respectively among Landsat TM 7 bands. This paper contributes to the efficient image processing of the spatiotemporal sedimental changes.