EPANET

EPANET performs long-term simulation of hydraulic behavior and water quality in water distribution system pipe networks

A network consists of pipes, nodes (junctions of pipes), pumps, valves, tanks or storage reservoirs.

EPANET tracks the flow of water in each pipe, the pressure at each node, the height of water in each tank, and the concentration of a species chemistry throughout the network during a simulation period composed of several time steps. In addition to chemical species, water age and source tracking can also be simulated.

SOLIDOS provides an integrated environment for editing network input data, running hydraulic and water quality simulations and viewing the results in a variety of formats using the EPANET engine. These include color-coded network maps, data tables, time series graphs, and contour plots.

EPANET was developed by the Water Infrastructure Division of the US Environmental Protection Agency's Center for Environmental Solutions and Emergency Response. (formerly Water Supply and Water Resources Division of the National Risk Management Research Laboratory)

In the EPANET node, you can:

• Properties - Edit EPANET properties, listed below
• Calculate - calculate the EPANET network, see the command EPANETCALC, for more information
• Import - imports an EPANET INP file and draws the network in Model Space, see command EPANETIMPORT, for more information
• Export - exports an EPANET INP file, see the command EPANETEXPORT, for more information

The EPANET node, concentrates the settings that are normally seen in Options of the official EPANET program:

• Object
  • Auto Calculate - Recalculates the network on any changes made to components
  • It's Calculated - Informs if the network is calculated
• Hydraulics - The hydraulic options determine how the hydraulic behavior of the pipe network should be analyzed
  • Accuracy - Convergence criterion used to signal that a solution has been found for the non-linear equations that govern the hydraulics of the network
  • CHECKFREQ - Sets the number of solution attempts that pass during hydraulic balancing before the status of pumps, check valves, flow control valves, and pipes connected to the tanks are reset again. updated
  • DAMPLIMIT - This is the precision value at which solution damping and status checks on PRVs and PSVs should start
  • Maximum Loss Error - Another convergence criterion that requires that the head loss calculated by the head loss formula compared to the difference in nodal heads on each link is less than the value specified
  • Statistics - Type of statistical processing used to summarize the results of an extended period simulation
  • Emitter exponent - Power to which the pressure is raised when calculating the flow through an emitter device
  • Head Loss Formula - Formula used to calculate head loss as a function of the flow rate in a pipe:
    • Hazen-Williams
    • Darcy-Weisbach
    • Chezy-Manning
  • Specific Gravity - Ratio between the density of the fluid being modeled and that of water at 4ºC
  • MAXCHECK - This is the number of solution tests after which periodic status checks on pumps, check valves, flow control valves and pipes connected to tanks are stopped
  • Maximum Load Change - A third convergence criterion requires that the greatest absolute change in flux between the current and previous solutions be less than the specified value
  • Demand Multiplier - Multiplier applied to all baseline demands to make total system consumption vary up or down by a fixed amount
  • Demand Pattern - DefaultPattern
  • Status Report - Amount of status information to report after the simulation is done
  • If Unbalanced - Action to be taken if a hydraulic solution is not found within the maximum number of attempts: STOP to stop the simulation at this point or CONTINUE to use another 10 tests, with no link status changes allowed, in an attempt to achieve convergence
  • Maximum Trials - Maximum number of trials used to solve the non-linear equations that govern the hydraulics of the network at a given point in time
  • Relative Viscosity - Kinematic viscosity of the fluid being modeled in relation to the viscosity of water at 20 ºC
• Demand Model
  • Demand Modeling - EPANET hydraulic analysis allows two different ways to model water demands (i.e. consumption) at network junction nodes:
    • Demand Analysis (DDA) - requires that the demands at each point in time are fixed values that must be delivered regardless of the nodal pressures and connection flows produced by a hydraulic solution.
      This has been the classic approach used to model demands, but it can result in situations where the required demands are satisfied on us with negative pressures - a physical impossibility.
    • Pressure Analysis (PDA) - allows the actual demand delivered to a node to depend on the pressure of the node.
      Below some minimum pressure the demand is zero, above some service pressure the total required demand is supplied and between the demand varies as a function of the pressure power law. Using PDA is a way to avoid positive demands on us with negative pressures.
  • Pressure Exponent - The power to which the pressure is raised when calculating the demand delivered to a node under a pressure driven analysis
  • Minimum Pressure - The pressure below which no demand can be supplied under a pressure driven analysis
  • Pressure Required - The pressure required to provide the full demand of a node under a pressure driven analysis Note: The required pressure must be greater than the minimum pressure, otherwise the calculation will show the error 208
• Energy - Provides default values used to calculate pumping energy and cost when no specific energy parameter is assigned to a given pump
  • Pump Efficiency - Default pump efficiency
  • Price Pattern - Time pattern used to describe the variation in energy price throughout the day
  • Energy Price - The average or nominal price of energy in currency units per kw-hour. Only used to calculate cost of energy usage
  • Demand Charge - Additional energy cost per maximum kilowatt usage
• Import - controls parameters related to importing EPANET networks from INP files into Civil 3D
  To import the INP files, see: EPANETIMPORT
  • Links - INP information conversion table for transverse sections more links to be imported
  • Nodes - Table converting INP information to cross sections of nodes to be imported
  • Network - Network where nodes and links will be imported
• Intervals - Time options define values for the various time steps used in an extended period simulation
  • Total Duration - Total duration of a simulation. Use 0 to run a single period (snapshot) hydraulic analysis
  • Start Time - Time the simulation starts
  • Pattern Start Time - Times in all time patterns when the simulation starts
  • Report Start Time - Simulation hours when computed results start to be reported
  • Quality Time Interval - Time interval between forwarding the water quality constituent. The normal default is 5 minutes
  • Report Time Interval - Time interval between times when calculated results are reported. Normal default is 1 hour
  • Pattern Time Interval - Time range used with all time patterns a>. Normal default is 1 hour
  • Hydraulic Time Interval - Time interval between recomputation of the hydraulic system. Normal default is 1 hour
• Quality - Quality Options select the type of water quality analysis to Conduit and control how the calculations are performed
  • Chemical Name - Actual name of the chemical being modeled
    For example: Chlorine
  • Mass Unit - Unit of measurement of the modeled chemical
    Applies to the modeled chemical
  • Relative Diffusivity - Molecular diffusivity of the chemical being modeled relative to chlorine at 20°C
  • Quality Parameter - Type of water quality parameter being modeled
    It might be:
    • None - No quality analysis is performed
    • Chemical - Chemical destination and transport
    • Time - Analysis of the age of the water (measured in hours)
    • Tracked Node - Source tracking analysis (measured in percentage terms)
      For this option, also inform the tracked node name
  • Quality Tolerance - Smallest change in quality that will cause a new water parcel to be created in a pipe
    Quality Tolerance determines when the quality of one water parcel is essentially the same as another parcel. For chemical analysis, this may be the detection limit of the procedure used to measure the chemical, adjusted for an appropriate safety factor. Using too large a value for this tolerance can affect simulation accuracy. Using too small a value will affect computational efficiency. A typical setting might be 0.01 for chemicals measured in mg/L as well as water age and source tracking
  • Tracked Node - Name of the node whose flow is being traced
    Applies to source tracking only
• Reactions - The reaction options select the type of water quality reactions that are included in the analysis
  • Order of Reaction in Flow - Power to which the concentration is raised when calculating a mass flow reaction rate
  • Wall Reaction Order - Power to which the concentration is raised when calculating a pipe wall reaction rate
  • Flow Reaction Coef - Standard mass reaction rate (Kb) assigned to all pipes. This global coefficient can be overridden by editing this property for specific Pipes
  • Wall Reaction Coefficient - Wall reaction rate (Kw) assigned to all pipes. Can be overridden by editing this property for specific Pipes
  • Threshold Concentration - Maximum concentration to which a substance can grow or minimum value to which it can decompose. The rates of mass action will be proportional to the difference between the current concentration and this value
  • Coef of Dependence on Roughness - Factor that correlates the reaction coefficient of the wall with the roughness of the pipe

Note: To edit the above parameters, use the command EPANETSETTINGS