MODPATH Pane

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MODPATH (Pollock, 1994, 2012) is a separate program that uses the output of MODFLOW to perform particle tracking. The pane for this program is on the MODFLOW Packages and Programs dialog box under Post processors.

The user specifies starting locations for one or more particles and MODPATH will track the movement of those particles due to advection. MODPATH does not take dispersion or retardation into account. Particles can be tracked either forward or backward. One use of MODPATH is to estimate the recharge area of a well.  To do this, the user can start particles in every cell and note which ones end up at the well or start a large number of particles at the well and track them backwards in time to their starting locations.

The user can specify a large number of options that affect how MODPATH operates. In version 5 of MODPATH, some of these are specified in the main MODPATH input files whereas others can be specified by the user either interactively or in a "response file." ModelMuse only supports the "response file" method. However, if desired, the input files generated by ModelMuse can be used in an interactive session with MODPATH. In version 6 of MODPATH, all the options are specified in input files.

Response file options | Simulation file options

hmtoggle_plus1Modpath version
hmtoggle_plus1Output mode (SimulationType)
hmtoggle_plus1Treatment of evapotranspiration (IEVTTP)
hmtoggle_plus1Treatment of recharge (IRCHTP)
hmtoggle_plus1Stop particles entering a particular zone (MODPATH version 5)
hmtoggle_plus1Use Zone Arrays (ZoneArrayOption) (MODPATH version 6)
hmtoggle_plus1Which endpoints should be recorded?
hmtoggle_plus1Zone in which to stop particle (StopZone)
hmtoggle_plus1Treatment of weak sinks (WeakSinkOption)
hmtoggle_plus1Weak sink fractional threshold
hmtoggle_plus1Reference time for simulation (ReferenceTime)
hmtoggle_plus1Tracking direction

Version 5 options

hmtoggle_plus1Compute budget in all cells
hmtoggle_plus1Summarize final status of particle
hmtoggle_plus1Allow unlimited budget file size
hmtoggle_plus1Stop computing paths after a specified [maximum|tracking] time
hmtoggle_plus1Compact format (Options)
hmtoggle_plus1Binary output file (Options)
hmtoggle_plus1Error tolerance
hmtoggle_plus1Release time (backwards tracking)
hmtoggle_plus1Maximum [tracking] time
hmtoggle_plus1Beginning time (BeginPeriod  BeginStep)
hmtoggle_plus1Ending time (EndPeriod  EndStep)
hmtoggle_plus1Maximum size of composite budget file (MAXSIZ)

Version 6 options

hmtoggle_plus1Treatment of weak sources (WeakSourceOption)
hmtoggle_plus1End of particle tracking (StopOption)
hmtoggle_plus1Maximum tracking time (StopTime)
hmtoggle_plus1Budget checking (BudgetOutputOption)
hmtoggle_plus1Particle to track (TraceID)
hmtoggle_plus1Use retardation (RetardationOption)
hmtoggle_plus1Advection observations( AdvectiveObservationsOption)
hmtoggle_plus1Treatment of ETS, UZF, MNW2, Reservoir, SFR, and Lake flows

Output times

hmtoggle_plus1Method of specifying times (TimePointOption)
hmtoggle_plus1Time interval for output (ReleaseTimeIncrement)
hmtoggle_plus1Maximum number of times allowed (TimePointCount)
hmtoggle_plus1Output times (TimePoints)