Abstract
Much of Japan's social infrastructure was built during the period of high economic growth in the mid-1950s to the early 1960s. This infrastructure continues to deteriorate with age, raising the question of how to respond to this problem in coming years. Water pipeline systems are a type of infrastructure vital to both industry and people in their everyday lives. The question of how to go about renewing and maintaining this infrastructure as the population declines involves many important issues. Water supply lines are particularly key facilities of water transmission systems, sending water from purification plants to distribution areas. The role of a water distribution network in securing water supply functions following a disaster is extremely important.
When considering the future of such a water pipeline infrastructure, not only economic cost but reducing the environmental impact must also enter into management thinking. This study therefore looks at the water distribution network from the two aspects of economic and environmental viability. The objective of the study is to determine from the standpoint of Life Cycle Assessment (LCA) both the extent of costs required for building and operating pipeline and pump facilities and also the amount of CO2 emissions that will result. Section 2 discusses the method of calculating the life-cycle cost (LCC) of a water distribution network and life-cycle CO2 emissions (LCCO2), and describes the service area that is the object of this research. Section 3 analyzes the impact on LCC and LCCO2 from differences in population density. Section 4 discusses the optimal approach to pipeline diameter downsizing assuming future population declines.
