• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.2
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• pp.117-126
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• 1999

Hampyong Bay is a semienclosed and macrotidal bay which opens to the eastern Yellow Sea through a narrow inlet in the southwestern coast of Korea. In order to understand the tidal-flat sedimentation in the semienclosed setting, morphology, sediments, accumulation rate and sea cliff erosion were investigated in the tidal flat of Hampyong Bay. The tidal flat of Hampyong Bay lacks intertidal drainage systems, and generally shows the concave-upward profile whose relief is designated by marked morphological features such as high-tide beaches, intertidal sand shoals and tidal creeks. Surfacial sediments of the tidal flat mainly consist of mud, sandy mud, gravelly mud, gravelly sand and muddy gravel, thus showing the textural characteristics of multimodal grain-size distribution, poorly sorting and positive skewness. The sediments generally coarsen landward due to the increase in coarse fraction content. Sedimentary structures are deeply bioturbated, but parallel lamination and lenticular bedding are locally found in the mudflat near mean low water line. Annual accumulation rates across the tidal flat (along Line SM) average -5.2 cm/yr with a range of -45.8~+4.2 cm/yr, indicating that the tidal flat is erosional. In general, erosion rates of upper and lower tidal flat are higher than those of middle tidal flat. Seasonally, the erosion rates are much higher during spring and winter when dominant wind direction corresponds to the long axis of Hampyong Bay. Sea cliffs are eroded at a rate of 1.4 m/yr. The biggest sea cliff erosion generally occurs 1~2 months later after tidal flats were extensively eroded. Such erosions of tidal Oats and sea cliffs in the semienclosed bay setting are interpreted to be due to wind waves coupled with local sea-level rise.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.10
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• pp.687-693
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• 2013

Coastal sand dunes have been seriously damaged caused by the development thoughtless for the environment and coastal erosion and destruction due to artificial structures like coast roads and breakwater. Hereupon, in this study we made a library of rhizobacteria that have the plant growth-promoting ability for plant rhizosphere of indigenous plants inhabiting in a coastal sand dune as well as the strong tolerance to salt, and evaluated the plant growth-promoting ability of these strains. Furthermore, we evaluated the effect of rhizobacteria on the growth rate of saline tolerant plants in sandy soil; selected out the most useful micro-organism for the restoration of a damaged sand dune. The effect of inoculation of strains selected from the first experiment on the growth of Peucedanum japonicum and Arundo donaxes planted in a coastal sand dune was evaluated. As a result, Bacillus aerius MH1RS1 had plant growth promoting activities: indole acetic acid (IAA) production, siderophores and 1-aminocyclopropane-1-carboxylate deaminase (ACC deaminase) activity, and also had a salinity tolerance. Also, in case of Peucedanum japonicum, the length of stems and weights of roots were enhanced by the inoculation of B. aerius MH1RS1. Fresh weights of stems and weights of roots in experimental group were, in particular, increased by 25% comparing with the control group. For an Arundo donax in experimental group, plant length increased by 18%, and weight of roots by 20% which is significant.

• Korean Journal of Environment and Ecology
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• v.37 no.5
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• pp.403-414
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• 2023

This study aimed to evaluate the ecosystem services and environmental sustainability index(ESI) of the Hasidong-Anin coastal sand dune ecological and landscapes conservation area using rapid assessment tools. As a result, the analysis of the environmental sustainability index, derived from the evaluation of ecosystem services in the Hasidong-Anin coastal sand dune ecological and landscapes conservation area, revealed that regulating services, cultural services, and supporting services were all rated below 50%. Especially, cultural and supporting services were identified as lacking. With these results, a SWOT analysis was conducted to develop strategies for enhancing ecosystem services in the Hasidong-Anin coastal sand dune ecological and landscapes conservation area. Six approaches were formulated, involving leveraging strengths as opportunities (SO strategy), minimizing threats using strengths (ST strategy), utilizing opportunities to address weaknesses (WO strategy), and mitigating weaknesses and threats (WT strategy). In the future, when promoting projects to enhance ecosystem services in the Hasidong-Anin coastal sand dune ecological and landscapes conservation area, it will be essential to address issues such as the restoration of currently damaged areas and prevention of future erosion-related damages. This will lead to an elevation of the value of the Hasidong-Anin coastal sand dune ecological and landscape conservation area.

• Journal of Wetlands Research
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• v.15 no.4
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• pp.493-500
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• 2013

Comparisons of surface sediment distributions in summer 1997 and 2011 and elevations on the tidal flats in April 1998 and March 2013 had been used for understanding the long-term changes of sedimentary environments at southern Kanghwa tidal flat, west coast of Korea. The mud sediments dominated in the eastern part and sandy mud sediments dominated in the western part of the tidal flat in 1997. In 2011, the surface sediments were dominant mud and sandy mud at Sunduri and Tonggum in the eastern part, sandy mud at Tongmakri in the middle part, and sand and muddy sand at Yeochari and Changhwari tidal flats in the western part. The area of mud sediments had decreased, but that of sand-mud mixed sediments extended to eastward tidal flat for 14 years. The long-term topographic changes showed that deposition occurred at Tongmakri and Yeochari and erosion occurred at Changhwari tidal flat during 15 years. These changes should be effected the local hydrodynamic changes by several constructions near the tidal flat since the 1990s.

• Journal of Forest and Environmental Science
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• v.18 no.1
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• pp.31-44
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• 2001

As one of the first tasks for Korean researchers, management system and coast sand dune fixation and stabilization in Japan were investigated and analyzed to introduce to Korea the many-sided importance and function of coastal forest and its change from the standpoint of social value. In this study some suggestions and ideas were proposed based on the analysis of data which were collected from the Shounai coastal forest in Yamagata prefecture for environmental characteristics, history, problems, erosion control facilities and shelter belt.

• Journal of Korea Water Resources Association
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• v.54 no.8
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• pp.607-616
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• 2021

The purpose of this study is to simulate the transport of nonuniform sediment considering the hiding-exposure effect numerically. In order to calculate the transport of multi-disperse suspended sediment mixtures, the set of advection-diffusion equations for each particle class is solved. The applicability of the numerical model is examined by comparing the simulation results with experimental data. In this study, we calculate the vertical distribution of total concentration of sediment particles using two approaches: (1) by considering the mixture as represented by a single size; and (2) by combining the concentration of the sediment corresponding to several particle size classes; From the simulation results, it is shown that both approaches calculate reasonable results due to the narrow range of size distribution. Under the condition of nonuniform sediment, the critical shear stress of the sediment particle is influenced by the size-selective entrainment, i.e., hiding-exposure effect. It is shown in this study that the effect of hiding-exposure effect on the erosion rates of fine sand is negligibly small.

• Journal of The Geomorphological Association of Korea
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• v.28 no.1
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• pp.51-66
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• 2021

This study shows that coastal sand dunes are negatively affected by coastal forests. In South Korea, planting pine trees on the dunes has been carried out to stabilize the dune landscapes and protect residential areas from coastal disasters since the 20th century. However, this strategy could reduce the resilience of dunes. In this study, we selected three monitoring sites with automated weather stations to compare the geomorphological and environmental characteristics between tree-covered and grass-covered dunes at Sohwang-ri, Boryeong-si, Chungnam Province for three years. In addition, we monitored the rates of erosion and deposition using eight pins along the dune crests. We found that the forest affected both wind velocity and direction, resulting in decreased blown sand supply to the dunes in front of the forest. The velocity of the strong winds faster than 5 m/s diminished to 10%-30% of the control sites, and the direction of northwesterly wind were skewed to the north by about 6°. Sand deposition occurred at about 15-20 m away from the pine forest and the amount was only 1/10 of the deposition within the grass-covered dunes. This study suggests that planting trees in coastal dunes is an undesirable strategy with negative impacts on the landscape management.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.35 no.6
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• pp.164-172
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• 2023

The grain size distribution of sand provides crucial information for understanding coastal erosion and sediment deposition. The commonly used sieve analysis for grain size distribution analysis has limitations such as time-consuming processes and the inability to obtain information about individual particle shapes and colors. In this study, we propose a grain size distribution analysis method using smartphone digital images, which is simpler and more efficient than the sieve analysis method. During the image analysis process, we effectively detect particles from relatively low-resolution smartphone digital images by extracting particle boundaries through image gradient calculation. Using samples collected from four beaches in Gyeongsangbuk-do, we compare and validate the proposed boundary extraction image analysis method with the analysis method that does not extract boundaries, against sieve analysis results. The proposed method shows an average error rate of 8.21% at D₅₀, exhibiting a 65% lower error compared to the method without boundary extraction. Therefore, grain size distribution analysis using smartphone digital images is convenient, efficient, and demonstrated accuracy comparable to sieve analysis.

• Economic and Environmental Geology
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• v.57 no.3
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• pp.293-303
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• 2024

River mining, the extraction of sand and gravel from riverbeds, is rising at an alarming rate to keep pace with the increasing demand for construction materials worldwide. The far-reaching deleterious effects of river mining include the lowering of water levels, the augmentation of turbidity, and the erosion of riverbanks, i.e., the disruption of water flow and alteration of river morphology. Aggregates demand, geolocation, and the economy of Bangladesh accelerated illegal extraction. However, limited research has been carried out in this region, despite the severe impact on aquatic and terrestrial ecosystems. To address the corresponding consequences and direct the scope for further research, it is required to evaluate existing studies of other countries having similarities in river morphology, climate, economy, and other related parameters. In this respect, based on previous studies, the effects of sand extraction are particularly prominent in India, having 54 cross-boundary rivers with Bangladesh. The geological profile of numerous rivers in the past decades has been altered due to natural aggregate mining in the Indian subcontinent. Hence, this study focused on relevant research in this region. However, the existing research only focuses on the regional portion of the aforementioned international rivers, which lacks proper assessments of these rivers, taking into account especially the mining effects. Moreover, several global rivers that have similarities with Bangladeshi rivers, considering different parameters, are also included in this study. The findings of this article underline the pressing need for more efficacious measures to address the adverse effects of river mining and safeguard ecosystems and communities globally, especially in the Indian subcontinent, where the situation is particularly vulnerable. For this reason, targeting the aforementioned region, this review highlights the global evidence in assessing the future effects of river mining and the need for further research in this field.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.552-561
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• 2023

The seafloor topography of Gomso Bay on the west coast of Korea was investigated using subtidal bathymetry and tidal-flat altimetry. Gomso Bay consists of 80% tidal flats and 20% subtidal zone, and is divided into an outer bay and an inner bay by the Jujincheon esturary channel. The outer bay tidal flat, has few tidal channels, has a concave topographic profile, and is characterized by the development of chenier and intertidal sand bars, giving it the appearance of gently sloping, dissipative beaches. The inner bay tidal flat has wide upper and middle tidal flats with a well-developed tidal channel system without cheniers. Moreover, the topographical cross-section between these tidal channels is convex upward, and shows the characteristics of a depositional environment greatly influenced by tidal channels and tidal action. An analysis of the horizontal movement of the tidal flat environment over the past 37 years investigating changes in the iso-depth lines in the Gomso-Bay tidal flat between 1981 and 2018 revealed that the Gomso-Bay tidal flat retreated gradually landward. As a result of analyzing the erosion and sedimentation characteristics of Gomso Bay, assuming that most of the water depth changes were due to changes in the elevation of the sea floor and sea level, an average of 1 cm (0 mm/y) of sediment was eroded in the outer bay over the past 37 years (1981-2018), In the inner bay, an average of 50 cm (14 mm/y) was deposited. Notably, the high tidal flats of the outer bay were largely eroded. Monitoring photographs of the coast showed that most of the erosion of the high tidal flats in the outer bay occurred in a short period around 1999 (probably 1997-2002), and that the erosion resulted from the erosion of sand dunes and high-tide beaches caused by temporarily greatly raised high tide levels and storms.