• Journal of Environmental Science International
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• v.28 no.12
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• pp.1061-1069
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• 2019

Common reed (Phragmites australis) is widespread in reclaimed land and wetland habitats. Every year, the common reed produces extensive colonies by means of underground rhizomes and ground-surface stolons. From an agricultural point of view, the common reed's large biomass is a good material for supplying organic matter. However, it has not yet been studied in terms of seedling production, transplanting conditions, and decomposition characteristics in reclaimed land. Seeds were harvested from the native common reed in Saemangeum, South Korea, the previous year and stored on an open field. The seeds were sowed in the greenhouse at the beginning of April. Common reed decomposition was studied from June to September, with the use of coarse mesh (5 mm) stem litterbags, on three samping dates and with five replicate packs per sample. These packs were dug in five soil condition (low-salinity topsoil, subsoil, high-salinity topsoil, subsoil, paddy topsoil) to 0.2 m and 0.4 m depth. The highest germination rate of common reed seeds was observed in non-salt solution, but the exhibited germination rate was 70% at 9.38 dS m^-1. The plant height of young reed decreased steadily with increasing salinity, but leaf number did not decrease by 9.38 dS m^-1. The survival rate of the two-year-old reed was 83.3%, which was 35% higher than that of the one-year reed. The transplant success rate was 0% in the no vinyl mulching in the soil, but the first year and second year seedlings survived rates were 63% and 83.3%, respectively, in vinyl mulching. Common reed decomposition rates were faster low salinity than high salinity. All nutrient contents were found to fluctuate significantly with time by soil conditions. We also need to study the growth rate of reed transplanting seedlings by soil moisture contents and the comparison of degradation in common reed tissues.

• Economic and Environmental Geology
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• v.35 no.5
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• pp.465-478
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• 2002

We measured subsidences occurred in a coastal reclaimed land, Noksan industrial complex, from May 2, 1996 to February 21, 1998, using 5 interferograms of JERS-1 L-band SAR. SAR with a spatial resolution of about 16 m can detect the two-dimensional distribution of subsidence that is difficult to be estimated from in situ measurements. Accuracy of the subsidences estimated by 2-pass DInSAR was evaluated using the measurements of Magnetic Probe Extensometer (accuracy of :${\pm}$1 mm) installed at 42 stations. DInSAR measurements were well correlated with the field measurements showing an average correlation coefficient of 0.77. The correlation coefficient was further improved to be 0.87 (with RMSE of 1.44 cm) when only highly coherenced (>0.5) pixels were used. The slope of regression line was 1.04, very close to the unit value. In short, DInSAR measurements have a good linear relation with field measurements so that we can effectively detect a subsidence in the coastal reclaimed area especially using pixels of high coherence (>0.5). The maximum accumulated subsidence was about 60 cm in the study area, while the subsidence in the northern and south western areas were less than 20 cm. The resuts show that DInSAR is extremely useful for geotechnical applications as well as observation of natural deformation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.5
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• pp.371-379
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• 2009

In this paper, we discussed methods and problems for estimating historical shorelines on a reclaimed land. Since many of coastal lands are unregistered in Korea, reclamation of public waters could cause complicated land ownership dispute. Unlike cadastral boundaries, historical shorelines can be represented by those of various locations due to lack of legal definition of shoreline as well as characteristics of shoreline changes, which directly influence on the calculation of coastal and submerged land areas. Through a case study for Anjeong industrial complex, a systematic method of investigating historical shorelines was suggested to resolve the problems. For a rocky coast where shoreline changes are not likely to occur, a shoreline based on tidal datum was retrieved using aerial photographs taken before the construction of reclamation. Compared with ground survey data, the shoreline was accurate, indicating that the digital photogrammetry was reliable.

• KCID journal
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• v.21 no.1
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• pp.1-16
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• 2014

The purpose of this study is to calculate agricultural water demand as considering landuse plan of the farm land on the Saemangeum tidal land reclamation project. This study based on the farm landuse plan(2012) and considered some items which did not included previous work like prevention water for resalinization for paddy and upland and muli-purpose water for upland. This study showed that the agricultural water demand estimated $145.123Mm^3/yr$, which is needed as much $14.792Mm^3/yr$ as more water than previous work. The difference comes from the change of unit water demand. Water demand is possible to be changed if guidelines are improved and detailed design work is completed through further study. Especially, the more studies for prevention water for resalinization in a tidal reclaimed farmland and water demand for a horticulture are needed.

• Magazine of the Korean Society of Agricultural Engineers
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• v.28 no.2
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• pp.53-62
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• 1986

An Idea of Standard Rural Area(SRA), the rural areas which have higher ruralities of the rice cropping region and also higher urban characteristics, was conceptualized to develop the tentative basic indices necessary for rural settlement design in reclaimed land. The SRA's were determined by a technique of the principal component analysis with relevant data from 81 counties or cities located in the west side of Korea(Chon-Nam,Chon-Buk, Chung-Nam, Kyung-Ki Do).By the definition of the SRA, the principal component analysis is seperately carried out by two subworks, analyses of rurality and urban characteristics. From the analysis, rurality of the SRA is characterized by four components which appears to describe the scale of farm management, intensive farming, soundness of farming and farming basis on rice cropping, while urban characteristics of the SRA by three components to describe the accessibility, keeping ratio of infrastructures and level of medical services. Through grouping and synthesizing two characteristics of all counties by each component score, 24 counties were classified as urban-rural harmonized region which is the same result as that obtained from the extraction index being more than 50% of available area to total area except 1 county. Therefore, SRA is defined as the group of counties having more than 50% of available area to total area.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.667-675
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• 2008

As a large construction such as highway, dam, reclaimed land etc. increase in number more and more, large amount of fill materials are required. However, it's difficult to obtain it because of environmental problems and economical efficiency. A alternative plan is to utilize a gypsum which is a by-product yielded from chemical plants and verify suitability to use gypsum as fill materials. Therefore, a characteristic of compaction for gypsum is analyzed and construction methods are given regard to this characteristic from construction of dike using gypsum. Based on the results obtained, it is found that moisture of gypsum in compaction should to be more dry side of O.M.C(optimal moisture content) because of sponge phenomenon. When gypsum is used to fill materials, standards of compaction should be decided from laboratory test.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.2
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• pp.45-52
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• 2016

The object of this paper was to evaulate modified proposed design equation in model test result in order to estimate uplift-resistance of timber pile of reclaimed land greenhouse foundation. Uplift resistance result of model test was increased to according to increased of contact area. Uplift-resistance result of field test tend to lineary increased to according to increased of embedment depth and contact area. Results of field uplift-resistance was evaluate compare with modified proposed design equation results of model test and Effective stress method. As the Effective stress method tend to underestimate, modified proposed design equation results of model test tend to similar type. As the contact area increase, difference between field uplift-resistance results and modified proposed design equation results of model test was considered uplift-speed.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.6
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• pp.139-147
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• 2014

Forecasting salinity in an estuary reservoir is essential to promise irrigation water for the reclaimed land. The objective of the research was to assess salinity balance and its temporal and spatial variations in the Iwon estuary reservoir which has been issued by its high contents of salinity in spite of desalination process for four years. Seepage flows through the see dikes which could be one of possible reason of high salinity level of the reservoir was calculated based on the salinity balance in the reservoir, and used as input data for salinity modeling. A three-dimensional hydrodynamic model, Environmental Fluid Dynamics Code (EFDC), was used to simulate salinity level in the reservoir. The model was calibrated and validated based on weekly or biweekly observed salinity data from 2006 to 2010 in four different locations in the reservoir. The values of $R^2$, RMSE and RMAE between simulated and observed salinity were calculated as 0.70, 2.16 dS/m, and 1.72 dS/m for calibration period, and 0.89, 1.15 dS/m, and 0.89 dS/m for validation period, respectively, showing that simulation results was generally consistent with the observation data.

• Journal of The Korean Society of Grassland and Forage Science
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• v.11 no.1
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• pp.22-29
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• 1991

This study was experimented to obtain the basic information on the changeable aspect and improvement of soil fertility in newly-reclaimed sloped land. Silage corn was cultivated under the six different treatments for 4 years. The relation between the amount or ratio of annual changes of soil physico-chemical properties and yield of silage corn were analyzed. Soil bulk density was decreased in 3rd year at topsoil, but that decreased in 4th year at subsoil. Soil organic matter also decreased in 2nd year at topsoil, and decreased continuously at subsoil. Bulk density and hardness of soil depths showed significant negative simple correlation with dry matter yield and cation exchange capacity showed positive. Correlation coefficient of chemical properties with dry matter yield were low. The range of annual changes of moisture percent, hardness and organic matter were wider than the other properties. The significantly different of physical properties were higher than the chemical properties, and those of topsoil were higher than subsoil. According to multiple regression between yield and physico-chemical properties of subsoil, bulk density and cation exchange capacity were in the greatest contribution at the variations, but bulk density was greatest at the ratios.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.640-648
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• 2009

Recently the truction of coastal reclaimation work has been extensively implemented in Korea. The Sondo New City is being established on the reclaimed land from the sea, construction companies of metro construction are planing to pull-out the sheet pile for saving the construction cost. In the case of soft marine clay, it is very difficult to pull-out the sheet pile by using the hydraulic hammer difficult. Therefore, the man of the field must be aware of vibration effect to the ground and the structure. For understanding the vibration effect to the ground during subway construction, the model was formulated with 1/25 braced-cut for subway construction. Scott and Iai(1989) proposed the law of the similarity for other experimental conditions. The laboratory model test was conducted under the vibration condition of sheet pile pulling out. The settlement on the ground surface was measured during the shaking table test. The pore water pressure was also monitored in the upper, middle, and lower layers of soil. The field settlement level and the pore water pressure can be predicted by using the results of the laboratory shaking table test.