EPANET - Open Source Software

INTRODUCTION:

EPANET is a public domain, water distribution system modeling software package developed by Water Supply and Water Resources Division. It performs an extended period simulation of hydraulic and water quality behavior within pressurized pipe networks and is designed to be "a research tool that improves our understanding of the movement and fate of drinking water constituents within distribution system". EPANET first appeared in 1993.

EPANET is available both as a standalone program and as an open-source toolkit. Its computational engine is used by many software companies that develop the more powerful, proprietary package, often GIS-centric. Therefore it is arguably considered as the industry standard.

EPANET provides an integrated environment for editing network input data, running hydraulic and water quality simulations, and viewing the results in a variety of formats.

HEADLOSS IN PIPE SEGMENTS:

EPANET hydraulic engine computes headloss along the pipes by using one of the three formulas:

1. Hazen-Williams formula.
2. Darcy-Weisbach formula.
3. Chezy-Manning formula.

Since the pipe segment headloss equation is used within the network solver. the formula above is selected for the entire model.

HEADFLOW CURVES OF PUMPS:

Within EPANET, pumps are modeled using a head flow curve, which defines the relationship between head imparted to the system by the pump and flows conveyed by the pump. The model calculates the flow conveyed by the pump element for a given system head condition based on this curve. EPANET can also model a pump as constant power input, effectively adding a given amount of energy to the system downstream of the pump element.

NETWORK SOLVER:

The network hydraulic solver employed by the EPANET uses the "Gradient Method" first proposed by Todini and Pilati, which is a variant of the Newton-Raphson method.

WATER QUALITY SIMULATION:

EPANET includes the capability to model water age and predict fow of nonreactive and under simplified conditions, reactive materials. This capability is frequently used to predict chlorine residuals within water distribution systems.

COMPATIBILITY:

EPANET uses a binary file format, but also includes the capability for importing and exporting data file. The input file can include data describing network topology, water consumption, and control rules, and is supported by many free and commercial modeling packages.

• PIPE2000
• H2OMAP Water
• H2ONET
• InfoWater
• IWWS
• WaterCAD
• WaterGEMS
• HAMMER
• SewerCAD

Most of this application allows for multiple demand conditions, planning scenarios, and various methods of integrating with other data sources an agency many already have in place not supported in EPANET, such as GIS, support additional types of analyses not found in EPANET.