• Geomechanics and Engineering
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• 제28권6호
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• pp.547-557
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• 2022

Dune sands are poorly graded collapsible soils lacking fines. This experimental study explored the technical feasibility of sustainable invigoration of fine waste materials to improve the geotechnical properties of dune sand. The fine waste considered in this study is fine marble waste. The fine waste powder was mixed with dune sand at different contents (5, 10,15, 20, 25, 50%), where the gradation, void ratio, compaction, and shear strength characteristics were assessed for each fine marble waste -dune sand blend. The geotechnical properties of the dune sand-fine marble waste mix delineated in this study reveal the enhancement in compaction and gradation characteristics of dune sand. According to the results, the binary mixture of dune sand with 20% of fine marble waste gives the highest maximum dry density and results in shear strength improvement. In addition, a numerical study is conducted for the practical application of the binary mix in the field and tested for an isolated shallow foundation. The elemental analysis of the fine marble waste confirms that the material is non-contaminated and can be employed for engineering applications. Furthermore, the numerical study elucidated that the shallow surface replacement of the site with the dune sand mixed with 20% fine marble waste gives optimal performance in terms of stress generation and settlement behavior of an isolated footing. For a sustainable mechanical performance of the fine marble waste mixed sand, an optimum dose of 20% fine marble waste is recommended, and some correlations are proposed. Thus, for improving dune sand's geotechnical characteristics, the addition of fine marble waste to the dune sand is an environment-friendly solution.

• Journal of Ecology and Environment
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• 제47권3호
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• pp.103-116
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• 2023

Background: This study analyzed the physiological adaptations of a woody plant, Vitex rotundifolia, in Goraebul coastal sand dunes from May to September 2022. Environmental factors and physiological of plants growing under field and controlled (pot) conditions were compared. Results: Photosynthesis in plants growing in the coastal sand dunes and pots was the highest in June 2022 and July 2022, respectively. Chlorophyll fluorescence indicated the presence of stress in the coastal sand dune environment. The net photosynthesis rate (P_N) and Y(II) were highest in June in the coastal sand dune environment and July in the pot environment. In August and September, Y(NPQ) increased in the plants in the coastal sand dune environment, showing their photoprotective mechanism. Chlorophyll a and b contents in the pot plant leaves were higher than those in the coastal sand dune plant leaves; however, chlorophyll-a/b ratio was higher in the coastal sand dune plant leaves than in the pot plant leaves, suggesting a relatively high photosynthetic efficiency. Carotenoid content in the coastal sand dune plant leaves was higher in August and September 2022 than that in the pot plant leaves. Leaf water and soluble carbohydrate contents of the coastal sand dune plant leaves decreased in September 2022, leading to rapid leaf abscission. Diurnal variations in photosynthesis and chlorophyll fluorescence in both environments showed peak activity at 12:00 hour; however, the coastal sand dune plants had lower growth rates and Y(II) than the pot plants. Plants in the coastal sand dunes had higher leaf water and ion contents, indicating that they adapted to water stress through osmotic adjustments. However, plants growing in the coastal sand dunes exhibited reduced photosynthetic activity and accelerated decline due to seasonal temperature decreases. These findings demonstrate the adaptation mechanisms of V. rotundifolia to water stress, poor soils, and high temperature conditions in coastal sand dunes. Conclusions: The observed variations indicate the responses of the V. rotundifolia to environmental stress, and may reveal its survival strategies and adaptation mechanisms to stress. The results provide insights into the ecophysiological characteristics of V. rotundifolia and a basis for the conservation and restoration of damaged coastal sand dunes.

• 한국지형학회지
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• 제24권3호
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• pp.149-159
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• 2017

Coastal dunes have many environmental and ecological socio-economic importances; various human activities, however, have impaired their structures and functions over the years. In 2016, environmental survey on coastal sand dune was carried out to report the present status and update the coastal sand dune list in 2001. This research analyzed the survey data in terms of geomorphological and socio-economic aspects. A list of the 189 coastal sand dune and information was updated by province. A 36.5% reduction in coastal sand dune area have been identified for using agricultural land, development area since the approximately 1940-50s. Development area in coastal sand dune covered small area as 5%, the use intensity was relatively hard. Furthermore, the difference by province also showed. Approximately 80% of the development area was concentrated in 20% of total sand dune several sand dune. It is generally accepted that coastal sand dunes were exposed high development pressure. However the result means that the general brief dose not apply for all sand dune. Therefore, characteristics of each sand dune should be analyzed and concerned the diverse management plans.

• International Journal of Concrete Structures and Materials
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• 제6권1호
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• pp.59-64
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• 2012

Sand-concrete is being researched for potential usage in construction in Saharan regions of Algeria, because of shortage in coarse aggregate resources. This research work deals with the effect of dune sand, available in huge quantities in these regions, on the properties of flowing sand-concrete (FSC) prepared with different proportions of dune and river sands. Mini-cone slump test, v-funnel flow-time test and viscosity measurements were used to characterize the behaviour of FSC in fresh state. The 28-day compressive strength was also determined. Test results show that an optimal content of dune sand, which makes satisfied fresh and hardened properties of FSC, is obtained. Moreover, the obtained flow index (constant b) calculated by the help of power-law viscosity model is successfully correlated to the experimental results of v-funnel flow time.

• The Korean Journal of Ecology
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• 제21권3호
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• pp.257-262
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• 1998

A syntaxonomical study about coastal sand dune vegetation in Kyungpook province was carried out. This study was accomplished by the methods of classical block-structure seeking and had-sorting of the $Z\"{u}rich-Montpellier$ School. The main purpose of this study is to clarify the syntaxonomical, synecological, syngeographical and syndynamical characteristics of coastal sand dune vegetation in Kyungpook province. The dune shrubs communities in Kyungpook province are consisted of 2 communities: Vitex rotundifolia community of southern type and Rosa rugosa community of northern type. And the dune grasslands communities are also consisted of 2 communities: Elymo-Caricetum kobomugi Ohba, miyawaki et $T\"{u}xen$ 1973 and carex kobomugi typical community. The subsidiary knowledges from this study will make possible to accumulate qualitative and quantitative information in the distribution pattern of coastal sand dune vegetation, and also will provide practical information for national biodiversity and conservation of coastal ecosystem.ecosystem.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.613-616
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• 2004

To find the best way to distinguish sand dunes from urban building and rural patches, textural analysis has been performed in Kimnyeong sand dune, Jeju. An aerial photo was re-sampled into one-meter. Homomorphic filters were applied to the original sub-scene and then high-pass filtered one. The entropy filtered one proves to be the best extraction method after high pass filtered-homomorphic filters in urban areas. The spectral values of sand dune area were similar to open land in rural area. In contrast, the texture values of sand dune area are more homogeneous than those of open land in rural area.

• Spatial Information Research
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• 제10권2호
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• pp.317-329
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• 2002

인간의 삶에 많은 영향을 끼치고 있는 해빈, 해안사구 등과 같은 해안지형은 역동적으로 변화하고 있고, 이에 대한 연구가 진행되고 있다. 해안지형의 변화량을 측정하기 위해 기존에는 측량기기에 의한 수준측량방법을 주로 이용해왔다. 이 연구에서는 기존에 고려되지 않았던 근거리 사진측량기법으로 해안사구 단면에 대한 고도값을 계산하였다. 즉 번들조정과 공선조건식의 역변환을 통해 비측량용 디지털 사진기로 촬영된 지상사진의 입체쌍으로부터 미지점의 고도값을 계산하였다. 6개의 기준점을 이용하여 번들조정을 수행하였고, 미지점 고도갈의 계산값과 실측갈을 비교한 결과 10cm 이내의 오차가 나타났다. 일반적으로 해안사구 지형은 모래질의 연약지반으로 실측시 수준척이 견고하게 고정되지 않고, 좁은 지역을 측량할 경우 인접지점에 교란현상을 발생시켜 측정오차가 크게 나타날 수 있다. 해안사구의 고도값을 측정하는 연구에서 디지털 사진측량방법은 기존의 수준측량이 갖는 문제점을 극복하면서 이를 대체할 수 있을 것이다.

• Journal of Ecology and Environment
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• 제39권1호
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• pp.17-29
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• 2016

We conducted the study on the relationship between the distribution of coastal sand dune plants and edaphic factors from the shoreline to inland in sand dune ecosystem. The application of TWINSPAN classification based on 10 species, led to the recognition of three vegetative groups (A-C), which associated with their habitats (foredune, hummuck in semistable zone and stable zone). The associations were separated along soil gradient far from the seashore. The relationships between species composition and environmental gradients were explained by canonical correspondence analysis (CCA). Distance from the shoreline was an important indicator to determine soil properties (pH, total ion contents, sand particle sizes, organic matters and nitrogen contents) from the seaward area to inland area and distribution pattern of coastal sand dune plants. Group A is foredune zone, characterized by Calystegia soldanella; group included typical foredune species such as Elymus mollis, Carex kobomugi, Ixeris repens, C. soldanella and Glehnia littoralis. Group B on semi-stabilized zone was characterized by Vitex rotundifolia, a perennial woody shrub. This group was associated the proportion of fine sand size (100 to 250 μm). The results on the proportion of soil particle size showed a transition in sand composition, particularly with respect to the proportion of fine sand size that occurred from the foredune ridge at 32.5 m to the Vitex rotundifolia community at 57.5 m from the shoreline. Group C on stabilized zone was characterized by Zoysia macrostachya, Lathyrus japonicus and Cynodon dactylon and were associated soil organic matter and nitrogen contents. The spatial distribution of plants in the Goraebul coastal sand dune system may result from the interactions between the plant species and environmental heterogeneity.

• Ocean and Polar Research
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• 제35권1호
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• pp.51-61
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• 2013

Two surveys were conducted in January 2006 and September 2007 with multibeam echosounder to investigate the dune shape, migration rate, and bedload transport rate using dune-tracking method on an offshore sand ridge at southern Gyeonggi Bay. The migration rates of dunes range from 1.8 $myr^{-1}$) to 56.0 $myr^{-1}$), at the upper northwestern side of sand ridge towards the southwest direction and from the center of the sand ridge towards the northeast direction respectively. Large (i.e. length 10-100 m) dunes show faster migration (0.3-23.4 $myr^{-1}$) ) than very large (i.e. length > 100 m) dunes because larger dunes have required a larger volume of sediments to be displaced. The decreases in dimensions and migration rates of dunes from the center of sand ridge to the lower part of southeastern side on the sand ridge can be ascribed to the decrease of sandy sediments availability, tidal currents with depth, and the coarsening of surface sediments from the crest of the sand ridge to the trough. Bedload transport rates on the basis of migration rates and dune dimensions decrease from 74.5 $m^2yr^{-1}$) at C transect to 35.6 $m^2yr^{-1}$) at R-02 transect.

• Journal of Ecology and Environment
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• 제35권3호
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• pp.167-175
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• 2012

Coastal sand dune systems are particularly fragile and threaten the environment. However, these systems provide fundamental ecosystem services to the nearby urban areas, acting, for example, as protective buffers against erosion. In this paper, we attempt to classify the biotope types of coastal sand dune ecosystems and select an index for the assessment of the conservation value. The types of biotopes are categorized based on the vegetation map; floras are examined in order to research the effects of hinterlands on coastal sand dunes. In addition, a naturalization rate and an urbanization index for each biotope type in hinterlands are analyzed. In the ecosystem of coastal sand dunes, the urbanization index and naturalization rate shows a higher value in sand dunes with areas of road, residential, and idle land in farm villages, rice fields, and fields. On the contrary, a lower value in the urbanization index and naturalization rate is present when typical biotope types, such as sand dune vegetation and natural Pinus thunbergii forests, are widely distributed. Based on these results, urbanization index and naturalization rate should be used as critical indices for the assessment of the ecosystem of costal sand dunes.