• Journal of environmental and Sanitary engineering
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• v.19 no.2
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• pp.45-50
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• 2004

To investigate the epilithic diatom community and water quality of the Osan stream, water samples were collected from the eight stations from April to September 2003. Sampling was two times before and after heavy rain. Total 52 diatom were identified and divided into 12 saproxenosus taxa, 6 saprophilous taxa and 34 indifferent taxa, respectively. The DAIpo values higher after heavy rain than before that. According to tolerance degree to the organic water pollution, all sampling stations ranged from $\alpha$-oligosaprobic to $\alpha$-mesosaprobic. Thus, the result indicates that the water quality of Osan stream is gradually improved by heavy rain.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.5
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• pp.77-91
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• 2009

The purpose of this study is to define the species composition of the soil seed banks at major wetlands in Nakdong river basin and central korea and to investigate how soil seed banks relate to aboveground vegetation and soil texture. In 2005, we sampled seed banks at Baksil reservoir, Jillal marsh, Deapyeng marsh, Hwapo marsh, Upo marsh and Junam reservoir in Nakdong river basin and Osan stream and Amsa-dong in Seoul. The soil seeds were estimated with the emergence method from April to October. Total numbers of species at the seed banks were 33 at Baksil, 18 at Daepyeong, 35 at Jillal, 56 at Upo, 32 at Hwapo, 47 at Osan stream, 54 at Amsa waterside, 31 at Amsa meadow. The species diversity in the soil seed banks of Upo marsh was the highest as 0.95. The community overlap index that compares aboveground with underground vegetation is high in the Upo marsh (0.34), Jilla marsh (0.36), and Osan stream (0.27). Soil texture affected distribution of 8 species, Lindernia procumbens, L. attenuata, Arenaria serpyllifolia, Juncus effusus, Persicaria thunbergii, Eragrostis multicaulis, Cyperus nipponicus, Scirpus fluviatilis. Considering the social and cultural values, soils at Amsa meadow, Hwapo marsh and Osan stream have worth to use for wetland restoration.

• Journal of the Korean Society of Hazard Mitigation
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• v.4 no.1 s.12
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• pp.51-56
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• 2004

In this study, the variation of water quality in Osan stream was investigated through continuous monitoring, and mass balance and metabolism occurred into water body were estimated to set up effective management plan for water quality of small urban stream. From the results of continuos investigation of water quality in Osan stream, the things written as follows must be previously done to improve water quality of main stream. Firstly, it need that effective management plan for tributaries must be set up to improve the water quality in main stream. Secondly, the counter plan for re-eruption of pollutants from sediment in main-stream is required to prevent inner pollution. In this study, we showed that small urban stream can be managed effectively by simple investigation to prevent deterioration of water quality. Therefore continuous monitoring for water quality in stream is important to improve water quality, furthermore matter cycle and mass balance happening in the stream environment must be correctly estimated to make up healthy stream environment.

• Proceedings of the Korea Water Resources Association Conference
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• 2003.05b
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• pp.871-874
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• 2003

• Journal of Korea Water Resources Association
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• v.43 no.5
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• pp.421-431
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• 2010

The hydromorphological structure assessment of the urban streams of Anyang stream, Yangjae stream, Osan stream, Jangsu stream, and Hakui stream 5 years the after close to nature stream restoration work was performed using LAWA (Laenderarbeitsgemeinschaft Wasser) for the investigation of the ecology of streams in urban areas. Based on the results, the effectiveness of stream restoration in urban areas was least in spite that existing various types of stream improvements were applied. Significantly, the grade of the longitudinal, the waterfront, and the use of land nearby waterfront was poorly evaluated. It would be estimated that this trend was due to the discontinuity of the longitudinal, the lack of diversity in waterfront, the installation of facilities nearby waterfront, and was due to the use of hard materials as like stones, blocks, frames, and mats in waterfront. The further studies on the implementation of structural diversity in waterfront should be performed for the improvement of the ecology of urban streams.

• Korean Journal of Ecology and Environment
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• v.36 no.2 s.103
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• pp.172-180
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• 2003

For a biological assessment of Pyeongtaek Reservoir and its major influent streams, an algal growth potential test (AGPT) was conducted with the blue-green algae Microcystis aeruginosa in March, June, September and December, 2000. The range and average value of AGPT were from 0 to 463 mg dw/l and 90 mg dw/l, respectively. For the influent streams in particular, the average of AGPT was the in the Hwangguchi Stream (343 mg dw/l). It decreased to 158, 66, 29, 21, and 21 mg dw/l in the Sojong Stream, Songhwan Stream, Osan Stream, Chinwi Stream, and Ansong Stream, respectively. The AGPT values in the reservoir ranged from 0 to 138 mg dw/1(mean 54 mg dw/1) with a tendency to increase in the upstream, which was close to the influent streams. In general, the AGPT values decreased further in the downstream. Immediately after the abrupt increase in influent discharge in summer, the AGPT value in the downstream almost doubled due to the proliferation of blue-green algae. The water quality of Pyeongtaek Reservoir and its influent streams further deteriorated during the drought period. Similarly, the AGPT value was the highest during this period. The AGPT values showed the closest correlation with the content of P (r = 0.999, p<0,001). Thus, it could be concluded that the content of P is highly effective in the growth of algae. In the Pyeongtaek Reservoir Watershed, the AGPT values varied in space and time. It was also closely related to the nutrient content of influent streams. The AGPT values revealed that the water quality state was hypertrophic (> 20 mg dw/1). Thus, control of the aquatic environment is essential. AGPT is very useful in evaluating the fertility and pollution state of the water as well as determining the nutrients that limit the growth of algae.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.729-733
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• 2012

오산천 어류상 분석을 통하여 생물종의 다양성 및 존속성 확보를 위한 서식처별 어류군집의 특성을 밝히고 자연 하안 및 서식처 조성 시 적합한 어류상에 대한 기초자료를 제공하고자 하였다. 본 연구에서는 오산천 일원의 3개 지점을 대상으로 각 서식처별 어류상을 조사하였다. 조사 결과 대한민국 고유종 2종을 포함하여 전체 9종 144개체가 채집되었다. 오산천 조사 지점 모두 수질이 좋지 않았으며 어류상은 빈약하였다. 기흥저수지 유입부에서는 상대적으로 다른 지점보다 많은 종수와 개체수가 채집되어 오산천 복원 시 수질개선과 함께 오산천 상류로 서식지 확장을 통한 복원이 가능할 것으로 사료된다. 복원 대상종은 대한민국 고유종인 왜매치, 치리 및 얼록동사리와 하상의 상태를 개선할 수 있을 경우에는 참마자와 모래무지를 포함할 수 있을 것으로 사료된다.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.6
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• pp.53-63
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• 2012

The objectives of this study were to develop a linked watershed-waterbody modeling system and to assess the impacts of indirect wastewater reuse on irrigation water quality. The Osan stream watershed within Gyeonggi-do of South Korea was selected for this study. The linked modeling system was composed of the SWAT (Soil and water assessment tool) and QUALKO2 models. The SWAT model was calibrated and validated using the stream discharge and water quality data from 2010 to 2011. Runoff and non-point source pollutants from each subbasin and stream discharge from 1980 to 2009 were simulated by the SWAT model and applied to the QUALKO2 model. The QUALKO2 model was calibrated and validated under the conditions of low water and normal discharges, respectively. Finally, The 10-day irrigation water quality from April to September was simulated. The statistical measures of coefficient of determination ($R^2$), reliability index (RI), and efficiency index (EI) were used to evaluate the system performance. The $R^2$, RI and EI values ranged from 0.5 to 1.0, 1.03 to 1.92, and -35.03 to 0.95, respectively. The 10-day irrigation water quality showed the concentrations of BOD and coliform exceeded the water quality guidelines for wastewater reuse. The linked modeling system can be a useful tool to estimate non-point source pollutant loads in watershed and to control the water quality of effluent from a wastewater treatment plant and irrigation water in the downstream waterbody.

• Ecology and Resilient Infrastructure
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• v.6 no.4
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• pp.208-216
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• 2019

This study investigated design factors and removal efficiencies of a sheet flow channel as natural type water improvement techniques in the stream. The channel was designed considering the design factors, then constructed and monitored in the test bed of the Osan stream's floodplain. Water lever, velocity, discharge, T-P, T-N, and NO₃-N were monitored and the removal efficiencies and design formula were suggested. Overall efficiencies of T-P, T-N, and NO₃-N range 10 - 20%, and they show consistent relations with residence times. Minimum velocity requirement is also suggested from the relation of algae conditions and velocities. Relation formula of residence time and removal efficiency will be applicable in the design and operation process of a sheet flow channel.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.4
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• pp.77-91
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• 2011

This study tries to find a streambed scouring and sedimentation characteristics through the Rosgen(1994)'s stream classification system while experiencing several flood events. The Jinwee and Osan streams, the tributaries of Anseongcheon were selected. The streams showed type C or type E. By the classification results, two Type C tributaries one Type C stream and one Type E tributary were selected. For the four selected stream reaches, the analysis of streambed change was implemented by using numerical model CCHE2D (Center for Computational Hydroscience and Engineering). To prepare the inlet boundary conditions of each stream, the WMS (Watershed Modeling System) HEC-1 was used and the streamflows of 50, 80, and 100-year return period were generated and the outlet boundary was set to an open boundary condition. The simulation results showed that when the flood pulse periodically the streambed changes also appears regularly. The results can be used to acquire the basic data for stream restoration.