Preface

This book incorporates selected topics on theory, revision, and practical application models for water supply systems analysis.

A water supply system is an interconnected collection of sources, pipes, and hydraulic con‐ trol elements (e.g., pumps, valves, regulators, tanks) delivering consumers prescribed water quantities at desired pressures and water qualities. Such systems are often described as a graph, with the links representing the pipes, and the nodes defining connections between pipes, hydraulic control elements, consumers, and sources. The behavior of a water supply system is governed by: (1) the physical laws which describe the flow relationships in the pipes and the hydraulic control elements, (2) the consumer demands, and (3) the system's layout.

Management problems associated with water supply systems can be classified into: (1) lay‐ out (system connectivity/topology); (2) design (system sizing given a layout); and (3) opera‐ tion (system operation given a design).

On top of those, problems related to aggregation, maintenance, reliability, unsteady flow and security can be identified for gravity, and/or pumping, and/or storage branched/looped water distribution systems. Flow and head, or flow, head, and water quality can be consid‐ ered for one or multiple loading scenarios, taking into consideration inputs/outputs as de‐ terministic or stochastic variables. Fig. 1 is a schematic description of the above.

**Figure 1.** Schematics of water distribution systems related problems.

The typical high number of constraints and decision variables, the nonlinearity, and the non-smoothness of the head – flow – water quality governing equations are inherent to wa‐ ter supply systems planning and management problems.

**Chapter 1**

**Guidelines for Transient Analysis in**

Additional information is available at the end of the chapter

pressure transients in municipal water systems.

Ivo Pothof and Bryan Karney

http://dx.doi.org/10.5772/53944

**1. Introduction**

**Water Transmission and Distribution Systems**

Despite the addition of chlorine and potential flooding damage, drinking water is not gener‐ ally considered a hazardous commodity nor an overwhelming cost. Therefore, considerable water losses are tolerated by water companies throughout the world. However, more ex‐ treme variations in dry and wet periods induced by climate change will demand more sus‐ tainable water resource management. Transient phenomena ("transients") in water supply systems (WSS), including transmission and distribution systems, contribute to the occur‐ rence of leaks. Transients are caused by the normal variation in drinking water demand pat‐ terns that trigger pump operations and valve manipulations. Other transients are categorised as incidental or emergency operations. These include events like a pumping sta‐ tion power failure or an accidental pipe rupture by external forces. A number of excellent books on fluid transients have been written (Tullis 1989; Streeter and Wylie 1993; Thorley 2004), which focus on the physical phenomena, anti-surge devices and numerical modelling. However, there is still a need for practical guidance on the hydraulic analysis of municipal water systems in order to reduce or counteract the adverse effects of transient pressures. The need for guidelines on pressure transients is not only due to its positive effect on water loss‐ es, but also by the contribution to safe, cost-effective and energy-saving operation of water distribution systems. This chapter addresses the gap of practical guidance on the analysis of

All existing design guidelines for pipeline systems aim for a final design that reliably resists all "reasonably possible" combinations of loads. System strength (or resistance) must suffi‐ ciently exceed the effect of system loads. The strength and load evaluation may be based on the more traditional allowable stress approach or on the more novel reliability-based limit state design. Both approaches and all standards lack a methodology to account for dynamic

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© 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

An example of that is the least cost design problem of a water supply system defined as finding the water distribution system's component characteristics (e.g., pipe diameters, pump heads and maximum power, reservoir storage volumes, etc.), which minimize the system capital and operational costs, such that the system hydraulic laws are maintained (i.e., Kirchoff's Laws No. 1 and 2 for continuity of flow and energy, respectively), and con‐ straints on quantities and pressures at the consumer nodes are fulfilled.

Traditional methods for solving water distribution systems management problems used lin‐ ear /nonlinear optimization schemes which were limited in systems size, number of con‐ straints, and number of loading conditions. More recent methodologies are employing heu‐ ristic optimization techniques such as genetic algorithms or ant colony as stand alone or hy‐ brid data driven – heuristic schemes.

This book addresses part of the above topics and is comprised of seven chapters: (1) Guide‐ lines for transient analysis in water transmission and distribution systems – identifying ex‐ treme impact failure scenarios to be considered in transient analysis design following by guidelines for surge control devices selection, location, and operation; (2) Model based sus‐ tainable management of regional water supply systems – an integrated optimal control wa‐ ter resources systems modeling approach for linking surface, groundwater, and water distri‐ bution systems analysis in a single framework; (3) Infrastructure asset management of urban water systems – an overview of infrastructure asset management methodologies for urban water systems with examples from the water industry; (4) Energy efficiency in water supply systems: GA for pump schedule optimization and ANN for hybrid energy prediction – a hy‐ brid genetic algorithm model for optimal scheduling of pumping units in water supply sys‐ tems; (5) Water demand uncertainty: the scaling laws approach – formation of scaling laws through combining stochastic models for water demand with analytical equations for ex‐ pressing the dependency of the statistical moments of the demand signals on the sampling time resolution and on the number of consumers; (6) Error in water meter measuring due to shorter flow and consumption shorter than the time the meter was calibrated – a practical hydraulic study on testing measurement errors due to shorter consumption times than the time the meters were calibrated for; and (7) Methodology of technical audit of water trans‐ mission mains – practical indicators for water mains rehabilitation decision making.
