Abstract
The pollution evaluation of the rivers and streams in Aso caldera area was done by principal component analysis and multiple regression analysis out of the methods of multivariate analysis based on the results of field survey on the flow rate, water-quality and bottom fauna of the rivers in December of 1984, April, August and November of 1985.
The first principal components Z1 (7S, 16I) and Z1 (7S, 9I) were selected as to show the water-quality characteristics of Aso large volcanic basins.
The products of the difference of the first pricipal component scores and the ratio of the flow rates show some measures of the total amount and the sources of water pollution substances such as iron.
The mutiple regression analysis between bottom fauna and water-quality parameters show that fluoride is the most effective substance for the bottom fauna, and also the correlation between the first principal component Z1 (10S, 9I) and diversity index of fauna community DI (N) is shown as DI (N) =1.888e-0.192Z1
Then it was found that the pollution evaluation of the river environment in Aso caldera area could be done through the methods above and the living of bottom fauna in the rivers are interfered according to progress of the water pollution due to volcanic area characteristics.
