• Journal of Environmental Science International
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• v.14 no.1
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• pp.33-40
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• 2005

The size of minimum order stream has a very sensitive effect on runoff analysis model using the divergence characteristic of stream. Therefore, in this study, the threshold area of minimum order stream has been examined the change characteristic of topographical parameters. The subject basin of the research was the upper basin of the Kumho water gage station which is located in the middle of the Kumho river. The 1:25,000 numerical geography which was constructed $10{\times}10m$ mesh was used. The range of investigation of topographical parameters are number of stream order, length, area, slope, basin relief, sinuosity ratio, drainage density and total stream length etc. It was found from the result of analysis that the threshold value of minimum order stream has a very big effect on topographical parameters of basin. It was found that the threshold area of minimum ord er stream revealed under $0.10km^{2}.$ Furthermore, the parameters showed a serious change except for over $0.10km^{2}.$

• Journal of Environmental Science International
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• v.14 no.8
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• pp.739-748
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• 2005

The purpose of this study is to analyze seasonal changes in structure and landscape of Gongji stream corridor in Chuncheon, and to suggest some guidelines to contribute to creating a desirable close-to- nature stream. The study seasonally surveyed floodplain and revetment conditions, channel micro-topography, streamflow level and velocity, and vegetational cover. Flooding, water level, and vegetation were major factors of affecting seasonal changes in streambed structure and stream landscape. Small sand bars and islands were considerably disturbed by flooding and water level change. However, large islands and sand bars in the upper and middle section of the study stream remained or reappeared even after flooding. Flooding also tended to repeat channel sedimentation at the same spot. Controlling water volume of the Euiam Lake, which is adjacent to the study stream, caused higher water level downstream in the dry seasons. The majority of vegetation in sand bars and islands was washed away by the floods. Vehicle passing, crop cultivation, and ball game were other elements which disturbed vegetation in the floodplain. Creating a close-to-nature stream should reflect micro-topographical changes of channel by flooding, prevent improper vehicle entry and human use, and remove concrete material in the revetment and floodplain.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.330-335
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• 2005

This study was performed for the analysis of the variation characteristics on riverbed according to the arrangement of stream. It was monitored of the variation progress of riverbed dependent on the elapsed time after the arrangement and It was studied that the hydraulic adjustment of the riverbed caused by the variation of the riverbed. The large amount of deposit just after the construction in which the riverbed was arranged to natural form was come from the reduction of flow rate by the installed artificialities such as weirs and stone weirs and by the stones or the concrete blocks attached to the stream sides of riverbanks. This phenomenon was well consistent with the usual characteristics that the accumulation is induced on upper stream of hydraulic artificialities and the erosion is induced on down stream of hydraulic artificialities. The large reduction of the deposit 1 year later after the construction showed that the riverbed eroded considerably because of the recovery of flow amount and the rise of flow rate.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.695-700
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• 1999

Stream and groundwater qualities of two rural watershes in the upper North Han river basin were monitored for 14months. Six to eight stream sampling sites and two to there groundwater monitoring wells were chosen and water samples were regularyl collected and analyzed with respect to total nitrogen(T-N), total phosphorus(T-P) and total suspended solids(TSS). Monitoring data were graphically analyzed with respect to time.Rainfall amout and intensity seemed to have an impact on stream T-N and T-P concentration changes. TSS concentrations were generally lower than the first class stream water quality standared, Both stream and groundwater qualities near livesstock feetlot areas were degraded indicating the feedlots have an impact on water quality.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• v.25 no.1
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• pp.35-46
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• 1997

Theory and observations relating to the photoelectrons are reviewed. The photoelectrons play a very important role in the photochemistry and energetics of the upper atmosphere. It is a dominant heating source for the ambient electrons in the ionosphere. This paper covers the solar EUV flux calculation, local photoelectron production rates and the two-stream approximation of the photoelectron transport in the upper atmosphere. Some data are compiled and tabulated for reference.

• Journal of Environmental Science International
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• v.31 no.5
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• pp.431-445
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• 2022

The Gwangju Stream is a major tributary of the Yeongsan River. To maintain environmental and ecological functions in the stream, the flow is secured by natural water from the Mudeung Mountain as well as waters discharged from Lake Juam and the Gwangju sewage treatment plants. A substantial amount of water is supplied into the upper reaches of Gwangju Stream from Lake Juam. To examine the ecological effects of the water input from Lake Juam on the Gwangju Stream, a field survey of phytoplankton community species and an evaluation of water properties was conducted at five stations, from station GJ1 before the inflow to station GJ5 in the lower region. Nutrient levels decreased in the vicinity of the Lake Juam inflow, suggesting that this water inflow can contribute to the reduction of eutrophication in the stream. The phytoplankton community was mainly composed of Bacillariophyceae, Chlorophyceae, and Cyanophyceae, and the community structure was similar to that of the other study sites located near the water inflow regions. The inflow of water from Lake Juam can affect water quality and the phytoplankton community over a limited area, reducing eutrophication and increasing water flow in the Gwangju Stream.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.6
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• pp.555-561
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• 2020

In this study, the applicability of Hunt's analytical solution for a two-layered leaky aquifer system, which was developed to estimate stream depletion due to the groundwater pumping of the upper shallow aquifer, was evaluated. The 5-year averaged stream depletions were estimated using Hunt's analytical solution for various combinations of hydraulic characteristic values such as transmissivity, storage coefficient of the two aquifers, interlayer leakage coefficient, stream-well distance, hydraulic conductivity of the streambed, and stream width. Through comparison with the numerical solution accurately simulated with a MODFLOW groundwater flow model, the analytical solution derived by regarding the stream width as a point was evaluated. It was found that the error in the stream depletion calculated by the analytical solution can be reduced to less than 0.05 when the stream-well distance is greater than the stream width or when the stream depletion factor (SDF) is more than about 3,000 days. In addition, when the streambed hydraulic conductivity is less than 1 m/d, the hydraulic diffusion coefficient of the lower aquifer layer is less than 100 ㎡/d, the hydraulic diffusion coefficient ratio of the upper and lower aquifer layers is 5 or more, and the leakage coefficient between the layers is less than 0.0004 m/d, the overall analytical solutions were overestimated compared with the numerical solutions.

• Journal of Korean Society of Forest Science
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• v.42 no.1
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• pp.39-54
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• 1979

Such stream characteristics as the numbers, lengths, orders of stream channels, and drainage density are the essential elements for the analysis of drainages in planning of watershed management in a drainage basin. The drainage net is the pattern of tributaries and master streams in a drainage basin as declineated on a planimetric map. Stream order is a measure of the position of a stream in the hierarchy of tributaries. Density of the drainage is given by the quotient of the cumulative length of stream and the total drainage area. Drainage density then is simply a length per unit of area. In this study, the Anyang-cheon upper-watershed is selected for the survey and analysis of the stream system and drainage density in view point of the useful collection of data for effective watershed management planning. The Anyang-cheon upper-watershed is consisted of about 12,600 hectars of drainage area including the 13 Sub-stream. Total length of the Stream (as described in the Stream Law) in the survey area is measured as much as 71.2km, and that of the Small-stream as descrived in the Saemaul Stream Survey Book (1972) is calculated as 43,010 meters. Besides of this lengths, measured about 43,410 meters of the Small-stream and about 71,900 meters of the Torrential valley through this study. The range of the drainage density among the 13 Sub-streams having sub-watershed is analysed as from 14.79 to 24.10, and average value of drainage density in the entire watershed is calculated as 18.21 in case of including the length of the Torrential valley and 12.50 in case of excluding the same. It is required that the standard classification system in classifing for the characteristics of identification among the Stream, Sub-stream, Small-stream, Torrent, and Torrential valley must be satisfied through joint study of the authorities concerned.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3B
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• pp.241-251
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• 2006

This study analyzed the topographical characteristics by extracting property factors of stream (stream order, number of stream, stream length, mean stream length) and property factors of basin (basin area, basin length, total stream length, total number of stream, basin mean width, form factor, maximum stream order, basin density, stream frequency, relief ratio, mean elevation, mean, slope, maximum elevation) from DEM (digital elevation model) and stream network generated by 1:5,000 NGIS (national geographical information system) data for the Bukhan-river basin. In addition, topographical factors for upper, mid stream and lower stream were analyzed and the mutuality of the factors by linear and nonlinear regression curve was identified.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.3
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• pp.39-50
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• 2006

In this study, the water quality investigated during 2002s to 2004s for Anyang river and its affluent that was based on biological and chemical methods as well as ecological index of each streams. The improving of water quality and the multiplicity of specious in the most streams except for Anyang, which was due to the improving of water quality and water resource. The seasonal dry states are completely disappeared, but water quality of Anyang main stream was classified as fifth grades water with BIP 8.51~10.00 and BOD 8.16~14.4mg/l in Anyang stream overall. And alpha-mesosaprobic in upper, mid parts and polysaprobic in down parts of Anyang main stream are appeared according to Saprobien system, respectively. The water supply of treated sewage is appeared that upgrading effects of water quality in Anyang main stream and affluents of Anyang city area, but the practical effects of "Saving Anyang River" could not gained because the water quality of other branches in upstream parts than upstream measuring point of Anyang main stream, Wanggok stream Sanbon stream in Gunpo and Eeiwang cities, was not improved.