Abstract
In Japan, expansion and accumulation of human activities have a great effect on water chemistry of rivers. Because changes in water quality persist for a longer time than those in the quantity of water, there is concern that qualitative deterioratation of water resources will be encountered in the immediate future. However, extensive studies on dynamic states of water chemistry of river are not emphasized so much, and therefore an examination of the quantitative relationship between water chemistry of river and characteristics of drainage basin such as geology, landform, landuse, and so on, is not sufficient. In this research, dynamic states of water chemistry of the Tone River system, which supplies the largest urban area in Japan with water resources, are demonstrated and compared with its characteristics of drainage basin. Longitudinal variations in chemical composition of the main stream of the Tone River system are strongly affected by the confluences of the tributaries which have highly developed basins. Comparison with characteristics of drainage basin suggests that seasonal variations in water chemistry are caused by discharge controls at water facilities.
