The Rising/Falling Condition rule modifier can be used to restrict the applicability of a rule (i.e., to turn the rule on or off as a function of the specified condition). The condition is evaluated every timestep. If the condition evaluates to TRUE, then ResSim includes the rule in the rule stack, evaluates it, and applies it within the release decision logic. However, if the condition evaluates to FALSE, ResSim ignores the rule (does not include the rule in the rule stack, does not evaluate the rule, and does not apply the rule in the release decision logic).

The Rising/Falling Condition rule modifier allows you to select one of eight conditions with which you can restrict the applicability of the rule. These conditions include:

  1. rising pool elevation
  2. rising or constant pool elevation
  3. falling pool elevation
  4. falling or constant pool elevation
  5. rising inflow
  6. rising or constant inflow
  7. falling inflow
  8. falling or constant inflow.

To apply a rising/falling condition to a rule:

  • Click the Rising/Falling Condition Edit button.

  • The Rising/Falling Condition dialog will open ("Figure: Rising/Falling Condition"). A Rising/Falling Condition is defined by the following attributes. You must select or enter a value for each attribute:

    Figure: Rising/Falling Condition


    • Condition—choose from:
      • Rising
      • Rising or Constant
      • Falling or COnstant
      • Falling
    • Parameter—choose from:
      • Pool Elevation
      • Inflow
    • Averaging Period—this is a range of time define in hours back from the current timestep. The period is used, along with Tolerance, to determine if the Condition is met. Think of the averaging period as time span over which the slope of the Parameter is computed.
    • Tolerance—The tolerance is used for the determination of the "constant" portion of the condition. If the difference in the Parameter over the Averaging Period is less than the Tolerance, the condition is considered constant — neither rising nor falling.
  • Click OK to save your settings and close the Rising/Falling Conditions dialog.

A check mark will appear in the Rising/Falling Conditions checkbox:

When you have finished entering data for your rule, be sure to click Apply before moving on to the next rule.

An example of a completed Release Function rule is shown in "Figure: Example of Completed Release Function Rule".

Figure: Example of Completed Release Function Rule