Abstract
The distribution of aquatic macrophytes in TanChon basin, a stream of the Han River, were investigated in terms of environmental gradient from June 1989 to March 1990. In the basin, 12 species of aquatic macrophytes were listed and four communities of Potamogeton crispus community. $P. octandrus$ community, $Hydrilla verticillata$ community and $Vallisneria$ asiatica community were recongized by character species. $P. crispus, P. octandrus$ and $V. asiatica$ were found in rapids while $H. verticillata , Ceratophyllum demersum$ and $Trapa japonica$ were done in pools. The depth of sediment $TanCh\u{o}n$ was showed as a exponential function of water velocity, Bd=exp (-K Wv). The values of Biochemical Oxygen Demand(BOD), Chemical Oxygen Demand(COD) and Suspendid Solid(SS) were recorded as range of 3.2~121.0mg/1, 4.2~54.5mg/1 and 4.1~114.0mg/1, respectively. And the linear positive correlation between BOD(X) and COD(Y) were expressed as Y=3.904+0.4308 X with $R^2$=0.9808 and also the correlation between BOD value(X) and SS value(Y) were done as Y=5.333+0.9606X with $R^2$=0.9700. In two dimensional analysis of BOD and water velocity, their clusters were showed similar types matching to communities classified by character species. However, no aquatic macrophyes were found at the site with BOD$\geq$50mg/l or DO$\leq$0.2mg/l.