APPLICATION OF A TECHNICAL PERFORMANCE ASSESSMENT TOOL TO SUPPORT WATER DISTRIBUTION SYSTEMS REHABILITATION

Nowadays water network design is more and more equivalent to network rehabilitation. Design of completely new systems is less and less frequent, whist there is an increasing need for reinforcement, replacement or renovation of existing infrastructures. Multiple design optimization techniques methodologies have been developed, but sometimes these are either too simplistic to be relevant in practical terms, or not easy to apply without the support from the experts who developed them, not only due to the complexity of the background theory, but also for the programming skills and computing capacity required. Engineers can use a number of software packages to assist them in applying some optimization tools. However, algorithm transparency and confidence on the results are key requirements for most designers, and with these packages they frequently feel insufficient awareness and control of the whole process. An added factor for the lack of willingness to use the existing optimization tools is the complexity of the real life problems: the viewpoints that need to be taken into account are frequently conflicting, difficult to express mathematically, and very different in nature. As a reaction to the referred difficulties, designers end up adopting very subjective criteria, based on their own experience and professional knowledge. The current availability of geographic information systems and water distribution simulation models suggest that an intermediate type of approach is appealing. This approach is based on the use of easy to understand and use tools that allow for the assessment and understanding of the systems behavior for the relevant viewpoints to be taken into account. This paper presents how technical performance assessment of water distribution systems can contribute to fill in the current gap between research and practice, specially if adequately integrated into a more comprehensive rehabilitation decision support tool, as presented in Alegre et al. (2006). The same case study, Brandoa distribution system, is used to illustrate how the methodology can be applied.