Abstract
Water and energy consumed by various urban activities are eventually released to the atmosphere and hydrosphere. Their impacts may not be negligible as the great amount of water and energy are dumped according to the growth of urban activities. To demonstrate the impact of urban growth on the water temperature released from wastewater treatment plants via a sewerage system, the decadal trend of the water temperature, as well as water amount and heat flux are revealed, and the factors affecting the trend are analyzed for the central Tokyo area. It is found that the effluent water temperature and the heat flux have been increasing over the past 36 years. Based on the model that quantifies the effluent water temperature, it is indicated that the increase of water temperature is attributed to the increase of supply-water temperature, the increase of the water used for bathing and the increase in the energy consumption for hot water supply due to the change of life style and the total energy demand increase.
