Keywords: entropic flow pattern, pipe failure, pipe resizing, double pipe network, system performance indicators.

The design of Water Distribution Systems (WDS) tries to achieve simultaneously different aims related to a desired good performance of the hydraulic system, namely what concerns flexibility in pipe failure situations to guarantee previously fixed values of pressure in all nodes of the system. To achieve that purpose the usual solution is the looped network system.

An important step concerning an objective grounding of the decision criteria was the definition of objective-functions to be optimized (either to be maximized or to be minimized). The usually used objective-functions are: minimization of the cost, maximization of the flexibility of the system and minimization of the pressures in the system, which lead to opposite decision criteria. In practice, the engineer must study, analyse and compare alternative solutions that will try to 'reconcile' these opposite objective-functions.

The present work aims to present a path history about WDS layout and diameter sizing criteria. A case study is presented and studied based on the traditional approaches (branched and looped network) and also on alternative methodologies (entropic flow pattern, diameter resizing and total or partial double piping) [1,2].

A case study is presented and covers the criteria to define the entropic flow pattern for pipe diameter sizing and the analysis of the performance level of the alternative network solutions to solve it.

The items quantified were the cost of the network, its correlation with the node pressures pattern and the performance level of the system in pipe failure scenario.

To compare results, objective non dimensional numerical indicators were defined (CR, ER and NPFI) and their values are exhaustively presented for each case studied, as well as the numerical procedure to obtain those results.

In a final stage, a 'decision matrix' summarizes all the obtained numerical indicators that can be helpful tools to make objectively grounded decisions on what concerns the 'final' layout to be chosen.

[1]

A. Templeman, "Entropy and Civil Engineering Optimization", NATO Advanced Studies Institute, Edinburgh, United Kingdom, 1989.

[2]

M. Malafaya-Baptista, "Double Pipe Looped Networks: A New Approach to Design and Maintenance", in B.H.V. Topping, (Editor), "Proceedings of the Eleventh International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 239, 2007. doi:10.4203/ccp.86.239

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