Forest river surveys were carried out at upper streams of several rivers in the Lake Biwa watershed to understand the water quality characteristics of the rivers, and to find out their relationships with forest features such as geographical, geological and vegetational data. The results showed: (1) Forests have some purification functions for nitrogen and organic matter, but become sources for most of ionic species. (2) Main mineral species in forest rivers are Ca2+, Mg2+ and Na+, HCO3, CO32–, Cl, SO42– and SiO2. (3) Loading from forests was 0.4–7 kg/km2/d for TN and 0.01–0.3 kg/km2/d for TP. (4) River quality reflects the properties of each forest, and is unique to the place, especially in ionic species such as Ca2+ and Cl. (5) A cluster analysis successfully categorized ionic components into several groups.

This content is only available as a PDF.
You do not currently have access to this content.