Abstract
Water demand depends on various factors such as global climate change, population decline, household composition change, increasing awareness about efficient water use and improvement on water-saving appliances. Even though it is important to evaluate the influence of each factor, there is a little research on that of household composition change on the future water demand. In this paper, we evaluate the impact of population decline and the change of household composition on the water demand in Matsuyama City, Ehime, Japan and water held by an upstream dam in a drought period. We also compare the influence with the impact of the global climate change. We use the 188 samples of domestic water use that was collected by meter reading every 2 months and distribute that into daily use by a temporal disaggregation method. While the population decline decreases total domestic water demand of the city by 7.0 %, the change of the household composition increases the total demand by 2.2 % because the number of people per household decreases. The minimum volume of water held by the dam decreases by 3.0 % to 5.61 x106m3 by the less water inflow due to the climate change, although that is covered by the population decline and the change of the household composition.
