• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.1 no.2
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• pp.59-72
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• 1996

The stratigraphy of the Gomso-Bay tidal flat consists of basement, preHolocene oxidized unit, and Holocene tidal sequence in ascending order. The oxidized unit is a yellowish brown stiff mud of the last stadial (or subglacial) stage before 12,000 yr B.P. This yellowish brown preHolocene unit does not contain any marine fossils, but contains plant roots, plant fragments, and also vertical and horizontal microfractures indicating soil-formation when exposed. It is regarded as interfluve deposits. The Holocene tidal sequence is composed of lower mud facies (upper-flat muds), upper sand and muddy sand facies (middle to lower-flat sands). This coarsening-upward and retrograding pattern of Holocene tidal deposits reflects a Holocene sea-level rise. The plots of $\^$14/C-age versus depth of dated samples (peats and shells) show that the sea level of 7,000 yr B.P. was located about 6.5 m below the present mean sea level, and the sea levels of 4,000 yr B.P. and 2,000 yr B.P. were also situated about 3 m and 2.5 m below the present mean sea level, respectively.

• Ocean and Polar Research
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• v.36 no.3
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• pp.235-246
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• 2014

The thalassinidean upogebiid Upogebia yokoyai Makarov, 1938 was first collected and described based on the specimens from the upper tidal flat of sandy shores of Jeju Island, Korea. Although this species was already reported in Japan and Russia, this is the first report of its occurrence in Korea. Upogebia yokoyai differs clearly from other upogebiid species previously recorded in Korean waters, U. major and U. issaeffi, by spinulation of the dactylus and propodus of pereiopod 1. In addition, some morphological comparisons are provided for identification of the three Upogebia species in Korean waters.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.687-697
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• 2019

By monitoring sediment grain size and level variation of tidal flat surface for 6 years (2005-2011), and also by mooring TISDOS (tidal-flat sediment dynamics observation system) on the low intertidal flat in 2008, we investigated the sedimentary environment of tidal flat in the dammed Yeongsan River Estuary. The tidal flat of the Yeongsan River Estuary lost 82 % of its area because of coastal development projects, and a narrow tidal flat below mean sea level now remains. Most of the tidal flat sediments are composed of silt up to 70-94 %, and show the characteristics of clay deficiency and silt dominance. This is closely related with the coastal development, which led to the destruction of high tidal flats where most mud settled, and the modification of tidal current patterns. Moreover, the estuarine tidal-flat sediments reveal seasonal variation. They are coarse with abundant silt during windy autumn to spring, fine with abundant clay during the less-windy and high-discharge summer. This phenomenon indicates that the behavior of sediment particles on the low intertidal flats of the Yeongsan River Estuary is influenced by wind waves for silt and fresh water discharge and the tidal process for clay. Monitoring results of the altitude of tidal flat surface showed that the study area had eroded at an average rate of -2.6 cm/y during the period of 2005-2011, and also that an unusual deposition with a rate of 4 cm/y occurred in 2010. The erosion can be explained by an increased tidal amplitude and a strengthened ebb-dominant tidal asymmetry after the construction of an estuary dike and the Yeongam Kumho Seawall. The deposition in 2010 seems to have been closely related to the mass production of suspended materials from dredging of the estuary.

• The Korean Journal of Malacology
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• v.14 no.2
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• pp.121-130
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• 1998

Studies on the distribution and growth of the mud mussel, Musculista senhousia, were carried out in the mud-tidal flat near Mokpo from August 1996 to July 1997. The patch distribution of the mussel was observed in the middle part of the tidalflat during the study period. Annual mean density was 8,215${\pm}$1,394 ind./m2 and annual mean biomass was 1,966.43${\pm}$668.49 g TWwt/m2 in total wet weight, 760.04${\pm}$279.13 gMWwt/m2 in meat wet weight, 209.93 ${\pm}$ 49.41 gMDwt/m2 in meat dry weight, and 109.66${\pm}$58.78 gAFDW/m2 in ash-free dry weight. The monthly mean size of shell length varied from 11.00 mm to 16.97 mm. Relationship between shell length (SL) and shell height (SH) showed a positively significant regression (SH=0.482SL+0.791, R2=0.940, P<0.001). Regressions of total wet weight (TWwt) (TWwt=7.601${\times}$10-5SL3.052, R2=0.905, P<0.001), and meat wet weight (MWwt) (MWwt=1.127${\times}$10-5${\times}$SL3.404, R2=0.784, P<0.001) on shell length were positively allometric, with highly significant correlation coefficient. The relationships between SL and meat dry weight (MDwt), and AFDW were MDwt=9.813${\times}$10-6${\times}$SL2.928 (R2=0.421), and AFDW=1.015${\times}$10-5${\times}$SL2.922(R2=0.810), respectively. The condition factor of the mussel has been increased from March and formed a peak in July and August. It was sharply dropped in September. These results suggest that the gonadal development of the species commenced to be occurred in spring and that main spawning occurred between August and September.

• Journal of the Korean earth science society
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• v.26 no.5
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• pp.443-458
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• 2005

Late Quaternary deposits of the core in the western area of the Nakdong River delta consist of four sedimentary units: Unit I, II, III and IV, in ascending order, controlled by the sea-level change since the last interglacial period. Unit I unconformable overlying Cretaceous basement rocks is composed of sandy gravel and sand deposited in a fluvial channel before the first marine transgression. Unit II composed of stiff massive mud is interpreted as a shallow marine deposits formed during the last interglacial period (probably MIS 5). The development of the fissures coated with oxidized materials in the upper part of Unit II is a feature of subaerial exposure, which indicates erosional contact with the upper Unit III. Unit III is made up of soft massive mud and soft shelly massive mud deposited in a tidal flat and a inner shelf, respectively, since the Holocene transgression (about 9,000 yr BP). Unit Ⅳ consisted of soft shell bedded mud and yellowish sandy mud was deposited in the delta environments during the regression (after about 5,000 yr BP). The lower shell bedded mud was deposited in a tidal flat and the upper sandy mud was deposited in the floodplain corresponding to present site of the Nakdong River delta.

• Journal of the Korean earth science society
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• v.27 no.3
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• pp.328-340
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• 2006

In Janghwa-ri of Kanghwa Island morphological changes in four transects, 112 surface, and 2 core sediments were analyzed to understand the seasonal variation of the muddy tidal-flat environment. Sedimentary of facies can be classified into four facies; sand, muddy sand, sandy mud, and silt. During winter, the coarse-grained sediment facies expanded seaward. In the subsurface part of the core sediments, poorly sorted silty sediments dominate the area. According to the Pb-210 isotope analysis, accumulation rates of the tidal flat in Jangwha-ri appear to be $5{\sim}19mm/yr$. In the study area, the result is suggestive of a rapid change in depositional environments in recent years.

• Journal of the Korean Institute of Intelligent Systems
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• v.27 no.2
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• pp.119-125
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• 2017

The mud flat in Korea is the geographical feature generated from the sediment of rivers of Korea and China and it is the important topography for pollution purification and fishing industry. The mud flat is difficult to access such that it requires the aerial survey for the high-resolution spatial information of the area. In this study we used drones instead of the conventional aerial and remote sensing approaches which have shortcomings of costs and revisit times. We carried out GPS-based control point survey, temporal image acquisition using drones, bundle adjustment, stereo image processing for DSM and ortho photo generation, followed by co-registration between the spatio-temporal information.

• Economic and Environmental Geology
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• v.44 no.1
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• pp.59-70
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• 2011

The surface sediment distribution in a tidal flat in 2001 was compared with that of 2008 using high spatial resolution remote sensing images and a GIS-based analysis. Maps of the surface sedimentary facies for each time frame were induced by an IKONOS data acquired in February, 2001 and a KOMPSAT-2 data acquired in April, 2008 using an object-based classification method. The area ratio of each surface sedimentary facies were estimated, and the results were compared each other for deducing the change in the sedimentary facies during the time interval. The result showed that the percentage of grains larger than very fine sand (0.0625 mm) has increased considerably since the early 2000s in the Hwangdo tidal flat. Mud flat facies has decreased 5.81 % in the late 2000s compared with the early 2000s. However, mixed flat and sand flat have increased 4.46% and 2.14%, respectively. A field campaign also supported the result. This study showed that the monitoring of changes in the surface sedimentary facies in the tidal flat is possible through a GIS-based analysis using high spatial resolution remote sensing images.

• Journal of Wetlands Research
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• v.22 no.2
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• pp.59-65
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• 2020

The purpose of this study is to determine the origin of organic matter on sediment at Sindu-ri tidal flat. Grain size, organic matter, C/N ratio and the 13C and δ15N ratio were measured at three stations (Stn. A, B, C) of the tidal flat. As a result, the spatial variation in sediment properties showed that organic matter was related positively to the sediment mud content. Organic matters originating from marine particulate organic matter (marine POM) and fish farm particulate organic matter (fish farm POM) showed sedimentation of organic matters at Stn. A, sandy tidal flat, though terrestial plant (TP) and benthic microalgae (BMA) did at Stn.C, muddy tidal flat. Meanwhile, Stn. B, the intermediate property of Stn. A and C, was affected by marine POM and BMA. Furthermore, it was revealed that the amount and origin of organic matters in the sediments depended on spatial variation, and the factors were different from the stations. Particularly, at the Stn. C, the sediment showed high concentration of TOC in terrestrial organic matter and smaller size particles (< 63 ㎛). These facts suggest the many small size particles and organic matter will affect the sediment environmental condition in the Stn. C.

• Korean Journal of Environmental Biology
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• v.33 no.3
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• pp.274-278
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• 2015

A newly recorded glycerid polychaete collected from mud of the tidal flat in the southwestern coast of Korea is identified as Glycera fallax Quatrefages, 1850 based on the morphologies of papaillae and ailerons on proboscis, parapodial postsetal lobes, and branchiae. In this paper, we provide a detailed description and illustration of Korean materials of this species and a key to the species of the genus Glycera from Korean waters.