ABSTRACT
The research presented in this chapter compares implications of increased investment and operational costs for the reliability of networks with direct pumping and those combined with balancing storage. Economic aspects have been taken into consideration by applying the Present Worth method. Using this approach, the reliability of two simple network layouts has been analysed manipulated through five different topographical patterns, three altitude ranges and four economic scenarios. Each of the 120 scenarios was further tested on 20 additional designs comprising gradual increase of pipe capacity combined with reduction in pumping capacity, while targeting the similar minimum pressure. The network reliability has been assessed with the resilience indices introduced in Chapter 5, namely the NBI and In. To process efficiently total 2520 scenarios, the network diagnostics tool (NDT) used in the analyses in Chapters 6 and 7 has been upgraded with cost calculations. The results show that cheapest design scenarios are not necessarily the least reliable ones. Furthermore, better reliability for the same level of investment is achieved if done into additional pipe capacity rather than into pump capacity/operation. Moreover, both strategies confirm that the point after which the further investment is useless indeed depends on the choice of economic parameters.
