1. Hydraulic Modeling of Water Distribution Systems
Grady Hillhouse
M. Eng. Water Resources Engineering
Texas A&M University

2. Introduction A large percentage of EWB projects involve water.
Many of these project include a transmission or distribution component.
A basic understanding of pressure conduit hydraulics is essential when designing water infrastructure.
In situations where solving pipe networks is too complex, modeling becomes necessary.

3. Outline Introduction to pressure conduit hydraulics
Introduction to EPA NET
Basics of Modeling
Only an introduction
If you have questions, ask!

4. Pressure Conduit Hydraulics
Summed up in two equations:
constant

5. Head Loss
Darcy-Weisbach head loss equation

6. Head Loss (cont.)

7. Pipe Networks
Demand

8. Solving Pipe Networks
Continuity at nodes

9. Solving Pipe Networks
Fixed grade node paths

10. Solving Pipe Networks
Loop Equations

11. Hydraulic Grade Line
Total energy less velocity head

12. EPANET Public domain (free!) Relatively simple
Uses the gradient method to solve pipe networks for flows and pressures.

13. Components in Models
Node – junction between other model elements. Can have external demands.
Pipe – convey water between nodes.
Reservoir – infinite source of water with a constant or periodically changing water surface elevation.
Tank – stores water . Water surface is at atmospheric pressure.
Pumps – impart energy to water
Valves – various methods of controlling flow or pressure

14. Skeletonization
Depending on the complexity of the system you’re modeling, in may benefit you to simplify the model.

15. What you provide the model
Layout and parameters of infrastructure
Demands
Initial conditions

16. What the model provides for you
Flow rates in pipes and tanks
Pressures at nodes

17. Examples

18. Final Notes A model is only as good as the input data you provide.
Reference the user’s manual!
Never ask the model to do something you don’t understand.
Always verify results by checking with hand calculations.
Questions?