• Korean Journal of Environmental Biology
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• v.19 no.2
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• pp.119-128
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• 2001

A biological assessment of water quality was carried out in the Pyungchang River water system, Gangwon-do, Korea from September 1999 through August 2000. The benthic macroinvertebrates collected seasonally from 15 field sites were identified mostly up to species level. Benthic macroinvertebrates composed of 109 species, 77 genera, 31 families, 10 orders, 4 classes in 4 phyla. Dominant species occurring in all the field sites were mostly ephemeropterans and trichopterans. On the basis of the values of species diversity and biological indices such as Trent Biotic Index (TBI) Modified Biological Monitoring Working Party Score System (BMWP) and Biotic Index (BI), the Pyungchang River Water system was generally regarded as showing oligosaprobic water quality.

• Journal of Korea Water Resources Association
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• v.34 no.1
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• pp.81-90
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• 2001

A dynamic flood frequency analysis model was proposed for the frequency analysis in ungaged catchment and applied to 6 subbasins in Pyungchang River basin. As the dynamic flood frequency model requires precipitation, rainfall loss system, and runoff analysis, we adopt the rectangular pulse model, the SCS formula, and the geomorphoclimatic IUH(GcIUH) for the application. Input data for the analysis was borrowed from the results of the statistical flood frequency analysis using L-moment method for the same catchment, and then the return period was estimated using the model. This result was also compared with the return period estimated from the statistical analysis. By comparing with the results from two cases, we found the dynamic flood frequency analysis gave higher estimates than those from statistical analysis for the whole subbasins. However, the dynamic flood frequency analysis model has a potential to be used for determining the design flood for small hydraulic structure in ungaged catchment because it uses only physical parameters for flood frequency analysis. And this model can be easily applicable to other watersheds as the scale effect is negligible.