Impacts of Skeletonization on Distribution System Hydraulic Transient Models

Skeletonization is the process of representing a water distribution network model by only selected pipes. Applications include merging series pipes and consolidating parallel pipes into a single hydraulically equivalent pipe with the same carrying capacity, removing pipes less than a specified diameter, and trimming dead end mains. This paper addresses the effects of network model skeletonization on surge analysis and includes a discussion of the factors that should impact skeletonization decisions. Case studies are presented to illustrate the sensitivity of transient pressure extremes for various levels of skeletonization. It is shown that skeletonization can introduce significant errors in estimating pressure extremes and can overlook water column separation and subsequent collapse at vulnerable locations in the distribution system. This can lead to poor design and operation as well as inadequate protection of water distribution systems and added maintenance costs.