Page 270 - Fair, Geyer, and Okun's Water and wastewater engineering : water supply and wastewater removal

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Chapter 7

Water Distribution Systems:

Modeling and Computer

Applications

7.1 WATERGEMS SOFTWARE
This chapter deals primarily with the topic of pressure piping as it relates to water distribu-
tion systems. If designed correctly, the network of interconnected pipes, storage tanks,
pumps, and regulating valves provides adequate pressure, adequate supply, and good water
quality throughout the system. If incorrectly designed, some areas may have low pressures,
poor fire protection, and even present health risks.
WaterGEMS (Haestad Methods Water Solutions by Bentley) is used in this chap-
ter as a tool to illustrate the application of various available software programs that
can help civil and environmental engineers design and analyze water distribution sys-
tems. It is also used by water utility managers as a tool to aid in the efficient operation
of distribution systems. This software can be used as a stand-alone program, integrated
with AutoCAD, or linked to a geographical information system (GIS) via the GEMS
component.
WaterGEMS is used primarily for the modeling and analysis of water distribution
systems. Although the emphasis is on water distribution systems, the methodology is ap-
plicable to any fluid system with the following characteristics: (a) steady or slowly chang-
ing turbulent flow; incompressible, Newtonian, single-phase fluids; and (c) full, closed
conduits (pressure system). Examples of systems with these characteristics include
potable water systems, sewage force mains, fire protection systems, well pumps, and raw
water pumping.
WaterGEMS can analyze complex distribution systems under a variety of condi-
tions. For a typical WaterGEMS project, you may be interested in determining system
pressures and flow rates under average loading, peak loading, or fire flow conditions.
Extended-period analysis tools also allow you to model the system’s response to varying
supply and demand schedules over a period of time; you can even track chlorine residu-
als or determine the source of the water at any point in the distribution system. In sum-
mary, you can use WaterGEMS for:

1. Pipe sizing
2. Pump sizing
3. Master planning
4. Construction and operation costs

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