• River and Culture
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• v.7 no.3
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• pp.23-29
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• 2011

• River and Culture
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• v.7 no.3
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• pp.12-22
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• 2011

• Journal of Korea Water Resources Association
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• v.36 no.6
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• pp.1069-1082
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• 2003

The Cheongdocheon has the reaches under reduction of stream flow. We analysed the cause of the reduction. We investigated the current status of facilities for agricultural water use. We also compared the discharge measurements with the results from the continuous simulation of watershed runoff The satellite image was a tool to find some reaches of stream flow reduction under doubt. Agricultural reservoirs block up the stream and water does not flow over the reservoirs except by storm. They also discharge water through diversion channels and the water diverted does not flow through the natural stream. Farmers directly take water from the stream by weirs. The infiltration gallery of water below the stream ground makes the reach dryness perfect in Kamakchon. These are causes of the stream flow reduction. The discharge measurements are less than the simulation results of watershed runoff, and we guess that the reaches investigated have dried. We found the reaches of stream flow reduction that were under doubt from some KOMPSAT satellite images with the resolution of 6.6 m. Then, we confirmed the reduction of stream flow by a field investigation. All the above reaches have infiltration galleries of water below the stream ground. The research results are a case study on the cause analysis on the reduction of stream flow. One can obtain the KOMPSAT image for a low price and can get prior information to find the doubtful reach of stream flow reduction.

• Journal of the Korean GEO-environmental Society
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• v.13 no.5
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• pp.59-68
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• 2012

The objective of this study is a comparison with simulation results of flood inundation by the construction techniques of river topography. For construction of river topography, the data used in this study are 1:5,000 topographic DEM, ASTER DEM and SRTM DEM provided by WMS. Also HEC-RAS and HEC-GeoRAS are applied to analyze of inundation depth and area. Flood inundations are simulated by 3 techniques in return periods and compared with the results. The results of this study are as follows; (1) Comparative analysis of the results shows that they have only a little difference in construction techniques of river topography at midsized catchment. (2) Flood inundations by ASTER DEM is to estimate larger than the other techniques in flood area (3) In case of SRTM DEM, the application can be expected to make use in the fields because of proper results in flood inundation analysis.

• Journal of Korea Water Resources Association
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• v.32 no.4
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• pp.489-499
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• 1999

This research investigated the applicapability of an improved algorithm to calculate the topographic index, ln($\alpha$/tan B), for the topography of Korea employing channel initiation threshold area(CIT) and an exponent for the gradient(H). hanjaechun subwatershed in Cheongdochun and Dongok subwatershed in Wichun test watershed were selected as study areas. The digital elevation models(DEM) of study areas have been made with the resolution from 10m to 100m. Application of CIT to the traditional algorithm provide reasonable computation method in considering channel pixel impact. Introduction of the gradient exponent(H) made it possible to obtain better flow convergence effect in concave topography comparing with the traditional multiple flow direction algorithm. The improved algorithm shows the capability to relax the overestimation problem of rising limb of hydrograph through reducing overestimated high value of topographic index.

• Journal of Korea Water Resources Association
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• v.38 no.7 s.156
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• pp.545-554
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• 2005

The detailed interdisciplinary surveys were conducted on the pattern of habitat use of dominant fishes during the spawning and adult stage. The hydraulic parameters of the depth and velocity, discharge, substrate cover streams, and distribution of fish in the Yeonggang, WiCheon, HoeCheon, GeochangwiCheon, CheongdoCheon, DanjangCheon (the Nakdong River Basin) were measured. The Habitat Suitability Criteria was developed for the two fish species (Zacco Platypus and Zacco Temmincki) and life stages(spawning and adult), habitat conditions (depth, velocity and covet). The Physical Habitat Simulation of the Instream Flow Incremental Methodology was applied to calculate for optimal flow and the ecological flow recommendation was proposed by choosing the largest one in the optimal flow. The ecological flow recommendation was $5.0\;m^3/s{\sim}10.0\;m^3/s$ (e.g., $6.5\;m^3/s$ in the NaeseongCheon). Also, the ecological flow recommendations were compared with the existing ecological flow and flow duration analysis.

• Journal of Environmental Science International
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• v.8 no.1
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• pp.7-18
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• 1999

Fauna and biological water quality using benthic macroinvertebrates were analysed and estimated macroinvertebrates. Samples were collected 5 times from the 7 sites in the river between April and December 1997, and the results are summarized as follows. The taxa of benthic macroinvertebrates was totally composed 81 species, 45 genus, 37 families, 15 orders, 8 classes in 3 phyla. Among them, aquatic insects were mostly abundant as 65 species, and also, there were a species of oligochaetes, 2 species of hirundinida, 6 species of gastropods, 5 species of polecypoda, and 2 species of crustaceans. Average individual numbers in the whole sampling sites was 815 per square meter, and insects were abundant (Approx. 80%). Among the insects, the major taxa were respectively ephemeroptera (Approx. 70%) and trichoptera (Approx. 18%). According to the average individual numbers in each site, Chung-do stream (site 1) showed the highest appearance rate as 262 individual/ $m^3$ (32.2%), and the lowest value was at the end of Miryang River (site 7) as 38 individual / $m^3$(4.7%). The dominant species among the whole samples was Ecdyomurus levis Navas, and dominance indices was 0.3. In each site, Ecdyomurus levis Navas was dominant species from site 1 to site 5, and dominant species at site 6 and 7 was respectively Hirudinidae sp. 1. Species diversity index in total average of samples was 2.66. Average of species diversity index according to each study site was the highest value at site 4 (H'=3.47), and site 2, 1, 3, 5, 6, and 7 in that order. According to the water quality as biotic indices, GPI value was 1.49 in total average of Miryang river, and the pollution indices evaluated secondary water quality criteria as $\beta$-mesosaprobics. In each site, the best water quality was at site 3, and it revealed the first water quality criteria as Oligosaprobic. It was then site 1, 2, 4 and 5 in the order of water quality, and was evaluated secondary water quality criteria as $\beta$-mesosaprobics, respectively. Site 6 was also revealed the third water quality criteria as $\beta$-mesosaprobics. The worst water quality was at site 7, which revealed the third water quality criteria as a-mesosaprobics.