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Calibration targets

Calibration targets, under Output Specification → Calibration Targets, are the observations a solved model is compared with. Targets may be heads, head differences between two locations, velocities, well discharges, or discharges of internal line boundaries.

Head specified targets

  • Label is a text label that helps you keep track of head calibration targets.
  • Level is the model level of the target.
  • X,Y is the coordinates of the target. Type the coordinates, or click the map pin Map pin in the cell and then click the map. The map pin is shown when the cell is empty. Clicking the point on the map changes it to a black square, which you can drag.
  • Observed Head is the target head.
  • Time is the time of the observation for a transient model. This time is measured from time = 0 at the start of the simulation. In a steady model, this parameter is ignored. In a transient model, you may input head targets at the same location but at different times. Head difference targets may be used to calibrate to temporal variations in head (for example, rate of drawdown) during a transient simulation, in addition to spatial head differences.

Head difference targets

This compares model-calculated head differences with target head differences. The difference is computed between two head targets in Head specified targets. This may be used to calibrate to temporal variations in head at one location during a transient simulation (for example, rate of drawdown), or to spatial head differences (for example, head gradients). The labels are chosen from the head calibration targets.

  • Label 1 is the first head calibration target.
  • Label 2 is the second head calibration target.

Velocity specified targets

  • Label is a text label that helps you keep track of velocity calibration targets.
  • Level is the model level of the target.
  • X,Y is the coordinates of the target. Type the coordinates, or click the map pin Map pin in the cell and then click the map. The map pin is shown when the cell is empty.
  • Observed Horizontal Velocity is the target magnitude of the horizontal component of the average linear velocity.
  • Observed Horizontal Direction is the target direction of the horizontal component of the average linear velocity. This is measured in degrees from the x axis, positive in the counter-clockwise direction.
  • Observed Vertical Velocity is the target vertical component of the average linear velocity. Positive is upward, negative is downward.
  • Time is the time of the observation for a transient model. This time is measured from time = 0 at the start of the simulation. In a steady model, this parameter is ignored.

This is useful for calibrating a model to a known discharge direction indicated by an observed chemical plume. You can specify the direction of the observed horizontal velocity parallel to the observed plume and compare this with the modeled horizontal velocity direction. If you also know the magnitude of velocity in the plume, you can compare modeled and observed horizontal and vertical velocity components.

Discharge specified well targets

Here you select one or more head-specified wells and compare their simulated total discharge with a target or observed total discharge. This could be used to calibrate to an observed total discharge from a group of flowing artesian wells, for example.

  • Label is the label given to this well or group of wells.
  • Wells Selected is the list of head-specified wells. Choose the well or wells to calibrate to.
  • Observed Discharge is the observed or target discharge of this well or group of wells.
  • Time is the time in a transient simulation. It is not used in a steady simulation.

Discharge specified line targets

Here you select one or more internal discharging line boundaries (head-specified internal, or river) and compare their simulated total discharge with a target or observed total discharge. This could be used to calibrate to an observed discharge at a stream gauge, or discharge from a pit dewatering system, for example.

  • Label is the label given to this line boundary or group of line boundaries.
  • Line Boundaries Selected is the list of internal head-specified line boundaries and river line boundaries. Choose the line or lines to calibrate to.
  • Observed Discharge is the observed or target discharge of this line boundary or group of line boundaries.
  • Time is the time in a transient simulation. It is not used in a steady simulation.