• Water for future
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• v.24 no.3
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• pp.49-60
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• 1991

As a second part of the study entitled "Field Measurement and Analysis of Fluvial Sediment in the Cheongmi-Strea", this study concerns mineralogical and contaminative characteristics of sediment particles collected at Wonbu-Gyo and Hanpyeong-Gyo in the Cheongmi-Stream. The mineralogical analysis of the bed sediment collected reveals that, in general , quarz is the most abundant mineral found in sands with feldspars and rock fragments in the next, which confirms what is known in the literature. The shape factor of sand particles is about 0.7, which also agrees to what is known in the foreign literature. The analysis also reveals that the clay particles collected are composed mainly of illite, kaolinate, and chlorite. The analysis of contamination reveals that there is no substantial difference between the contents of organic material and heavy metals in the surface water and those in the pore water beneath the river bed. It is because the sampling for this analysis was conducted right after the September flood during which the fresh top soil from the upstream watershed replaced the old bed sediment and pore water that would probably be more contaminated. The contents of geavy metals in the bed sediment of sand particles do not exceed those in the soils adjacent to the river. For fine sediment such as clays, however, the contents of heavy metals, especially of mercury and zinc, far exceed those in the soils adjacent to the river. These fine sediments are transported downstream in the form of wash load and deposited in part on flood plains, which could be a new source of contaminants.taminants.

• Journal of Environmental Science International
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• v.9 no.1
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• pp.49-55
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• 2000

An EMERGY analysis of the main energy flows driving the economy of humans and life support systems consists of environmental energies, fuels, and imports, all expresses as solar emjoules. Total EMERGY use(720.0 E20 sej/yr) of the Nakdong River Basin is 96 per cent from imported sources, fuels and goods and services. EMERGY flows from the environment such as rain and geological uplift flux accounted for only 4 percent of total EMERGY use. Consequently, the ratio of outside investment to attracting natural resources was large, like other industrialized areas. EMERGY use per person in the Nakdong River Basin indicates a moderate EMERGY standard of living, even though the indigenous resources are very poor. Population of 6.66 million people in 1996 is already in excess of carrying capacity of the basin. Carrying capacity for steady state based on its renewable sources in only 0.226 million people. EMERGY yield ratio and environment loading ratio were 1.07 and 28.52, respectively. EMERGY sustainability index, a ratio of EMERGY yield ratio to environment loading ratio, is therefore less than one, which is indicative of highly developed consumer oriented economies. This study suggests that the economic structure of the Nakdong River Basin should be transformed from the present industrial structure to the social-economic structure based on an ecological-recycling concept for the sustainable use of the Nakdong River.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.448-452
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• 2004

Instream flow is necessary to manage the basic function of the rivers. The evaluation method of instream flow in a big river has been studied widely. However, the study in a urban hasn't researched. In theses days the environmental function of a river becomes very important. The evaluation method and secure of instream flow are basic conditions to perform it. Especially view of stream, recreation, protection of ecology are highly demanded In a urban according to the multipurpose of river spaces. In this paper the evaluation methods of instream flow were compared and investigated with many papers. This paper presents a proper evaluation procedure of instream flow in a urban stream through comparison and examination. According to the demanded hydraulic conditions the method can be considered the environmental function depend on the purpose of river restoration. The relationship of the coefficient of roughness and the slope of the river bed were examinated in order to estimate the minimum instream flow corresponding to proper Hydraulic conditions. Also calculate the instream flow of Sueng-gi stream in In-cheon.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.1
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• pp.61-67
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• 2021

With the recent development of bathemetry technology, the hydrographic surveying method has been changed from single beam depth device use to multi beam acoustic sounding technology. Also, various studies have been reported to obtain high accuracy and precision in the process of river bed topographic data. Especially south korea is geographically on three sides of the sea and the river topography is very developed. To build information about the underwater, and riverbed status, the public investigations has been continuously progressed. In this study, We investigasted the riverbed topography near Baeckma river leisure park. for this purpose, In this study, as the first preliminary survey, location of navigational dangerous objects and reefs and the dangerous areas are identified. Also, ground control points is selected for the optimal GPS surveying. Secondary, through test surveying the Gain, TVG, and pulse length are determined. In addition, the investigation of dangerous objects for navigation is also conducted. As the last step, the error analysis are conducted for the acquired data, and this process involves the removal and adjustments of errors. This section includes the analysis of tide level and navigational contributions, and finally generates a submarine topographic map.

• Ecology and Resilient Infrastructure
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• v.7 no.2
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• pp.83-89
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• 2020

This hydraulic study analyzed the scour effect at fixed downstream weirs based on the changes in the upstream bed slope. The study was performed using six different bed slopes, that is, 0%, 2%, 3%, 4%, 7%, and 10% at 0.117 ㎥/s in all cases. The scour depth, scour length, and scour volume were measured using a broadband laser scanner to quantitatively analyze the scour at the downstream weir. This study also examined the adequacy of the designed apron length by comparatively analyzing the results of the scour experiments and the apron length calculated using conventional design standard formulas. The analysis of the local scour effect at the downstream weir showed that scour length and scour depth increased as the bed slope became steeper. A comparison between the results of the scour experiment and that of the conventional design formulas showed that both formulas of the National Construction Research Institute and the Bligh were distributed within the allowable values when there was no upstream bed slope. However, as the bed slope upstream of the weir gradually increased, the scour lengths of the apron deviated slightly from the values obtained from the conventional design formulas.

• Journal of Environmental Science International
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• v.7 no.3
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• pp.281-290
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• 1998

Thirty-eight sediment samples collected from the Youngsan River channel were analysed for Fe, Mn, Co, Cr, Cu, Nl, Zn and Pb to recognize the extent of contamination. Results showed that a wide range of contents was apparent far every metal over the study area. These differences have been mainly related to the textural variability of sediments. Exceptions to this were fecund in the contents of Cu, Zn, Pb and possibly Mn. The contents of Cu, Zn, Pb and Mn were particularly higher in the sediments loom the confluence of tributaries. Downstream profile of metal/Al ratios indicates that pollutant inputs from the Kwangju tributary are mainly responsible for enrichment of these metals in bed sediments of the Young-san River.

• Ecology and Resilient Infrastructure
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• v.2 no.4
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• pp.317-323
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• 2015

This study investigated the impact of the morphological change on a physical fish habitat in the downstream reach of a dam using long-term mobile bed simulation. The quasi-steady model was used for hydraulic simulation and the habitat suitability index model was applied for physical habitat simulation. For simulating long-term morphological change of the stream bed, The Exner equation was used. Sorting of bed material was also considered. The results of simulation showed that erosion and armoring process occurred in a reach downstream of the dam and change of physical habitat for Zacco platypus followed. These results indicate that channel morphology and substrate conditions effected the physical habitat for considering long-term investigation.

• Journal of Environmental Health Sciences
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• v.24 no.1
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• pp.38-46
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• 1998

This study was to investigate the effects of carbon loadings, temperature and expansion ratio on the waterborne organic removal by the biologically active GAC fluidized bed on a laboratory scale. The raw water to be treated comes from midstream of Han river. BACFB(Biological Activated Carbon Fluidized Bed) process was very effective to remove the biodegradable fraction of dissolved organic matter. The more carbon weighed, the more DOC removed in a range from 16.7 to 133.3 g/l. DOC and UV$_{254}$ were removed more than 40% and 20% above 20$\circ$C respectively. Between 5$\circ$C and 10$\circ$C, DOC and UV$_{254}$ were eliminated about 30% and 15% respectively. In general, even if the temperature was higher, DOC removal was a little sensitive, probably influenced by GAC's residual adsorption capacity. UV$_{254}$ reduction was little fluctuated in accordance with water temperature. The gradual increase in expansion ratio from 10% to 75% didn't greatly affect on the removal of DOC and UV$_{254}$. The expansion ratio, therefore, is not a key factor over the critical expansion ratio.

• Journal of Environmental Science International
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• v.11 no.10
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• pp.1075-1080
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• 2002

The hydrological frequency of the flood in July 2000 at Seosi stream basin in Gurye and the bed scour of the stream channel were estimated to investigate the bed scour related with Jeongjang bridge collapse. The storm over the basin in July 2000, 303mm/day was 103year frequency rainfall and the equivalent flood was 2580cms. As the results of 100year and 30year flood application, flood level 30.78~31.38m and mean velocity 3.79~4.03m/s were appeared. And the purification project of Seosi stream increased the velocity of the section near to Jeongjang bridge by the improvement of conveyance at the downstream. The local scour at pier was the major factor of bed scour at Jeongjang bridge site and the total scour at pier No.6 was increased from 2.32m to 2.45m by the purification project.

• Journal of Korea Water Resources Association
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• v.47 no.12
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• pp.1165-1176
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• 2014

In a river bend the water surface is inclined by the centrifugal force toward the transverse section. If channel slope and flow rate increase, the gradient is rising generally. There are lots of the flood damage at the bends of mountain river because the flood water levels have exceeded frequently the levee levels which are added a free board to the design flood water level. Therefore the superelevation should be considered in designing the mountainous river bend. In present study it was proposed to estimate the superelevation at the bend of mountain river and the superelevation coefficient defined from multiplying the sub-factors. The values of the influence factors for the superelevation coefficient were suggested from analyzing the superelevation measured at the bends in Yangyangnamdae river and the hydraulic experiments in gravel-bed channel with a $90^{\circ}$ bend. The applicability of these methods to estimate the superelevation at the bends in mountain river was verified by the superelevation measured at the bend in Naerin river.