Abstract
In order to clarify the effects of forest vegetation on the characteristics of river water quality and on the management of water resources, we investigated clean sources upstream for water supply in Japan and analyzed hydrological, geographical and water quality data of first class rivers in contrastive wet 1993 and dry 1994. Significant co-relation between broadleaf forest area and the concentration of COD and TOC was found and vice versa with coniferous forest area. The positive co-relation between broadleaf forest area and the mean runoff ratio was obtained and vice versa with coniferous forest area. Comparing the relation between the low runoff or the maximum runoff ratio in wet year of 1993 and broadleaf or coniferous forest area also, then we concluded that the broad leaf forest could play a better role for water resource management than coniferous forest.
