Abstract
It is important to consider wide-area water supply and asset management in an integrated manner to realize sustainable water supply systems. However, there is no established planning method for long-term operation and renewal of wide-area water supply systems which is adapted to temporal change of constraints such as water source availability, future water demand and facility aging. In this study, mathematical optimization was applied to make a long-term planning scenario of operation and renewal of wide-area water supply systems. And then a novel planning method was developed which can make an optimal scenario with the smallest cost under the necessary facility renewal condition.
As a case study, the developed method was applied to make a plan for next 50 years in a virtual water supply system composed of 8 water utilities, imagining the eastern area of Gunma prefecture. Constraints including topography, locations of purification plants, layout of main pipes, and temporal changes of water resource availability and water demand were given to the planning method. In the case of networking and consolidation of water purification plants among water utilities in a wide area, the average cost throughout the entire planning period was reduced by 10.4% compared to individual utility-based planning without networking. In addition, expenses for facility aging measures were reduced by 8.9% in the case of wide-area water supply system when shortening the service life time of water purification plant from 90 years to 70 years. It was shown that more economic operation and renewal can be achieved by wide-area water supply systems with measures for facility aging compared to individual utility-based planning without networking.
