Session3: Environmental Hydraulics
Title: SEASONAL COMPARISON OF PREDOMINANT FACTORS IN RIVER TEMPERATURE FORMATION IN AN URBAN RIVER
Junichi Nishimata, Hitoshi Miyamoto
In this paper, predominant factors of river temperature formation in each season were analyzed by using the field observation and heat budget analysis in the middle and lower parts of an urban river. The urban river analyzed was the first-class river, Tama River, flowing through the Tokyo metropolitan area. Treated water with a constant temperature flowed into the Tama River from several water reclamation centers located along with Tama River. Observational data analyses indicated that the influence of convective heat flux from the treated water discharge greatly affected the formation of river temperatures in the middle reach of Tama River in all seasons. On the other hand, in the lower reach, the river temperature flowed downstream with a nearly constant temperature. The heat budget analysis also showed that, in summer and autumn, the river temperature in the middle reach was more influenced by the treated water than that in the downstream reach. Other predominant factors in river temperature formation in each season were further discussed and compared by using the heat budget analysis.