A forecast run is a predefined sequence of model alternatives executed in a specific order during a forecast. Like model alternatives, forecast runs are not bound to a specific time window, allowing them to be reused for different forecast periods. To create a forecast run, you assign one model alternative to each necessary software application. You are not required to assign a model alternative to every position in the program order. During execution, the alternatives run in the sequence defined by the program order. Before creating a forecast run, you must first define model alternatives.

Forecast Run Editor

To access the Forecast Run Editor, go to the Setup tab, open the Models menu, and select Forecast Runs.

Forecast Run Keys

HEC-RTS automatically generates a unique key for each forecast run. This key is a string of one-character codes, each representing a selected model alternative. The order of characters corresponds to the established program order. The table shows example forecast runs and the associated keys.

Forecast Run Name

Key

No future precipitation

NNNNN

QPF

QNNNN

Two times QPF

SWRBE


In the Two times QPF example, the key SWRBE represents five selected model alternatives, each assigned a unique character, in the order of the program sequence.

Examples

There are many scenarios where you may need to create multiple forecast runs within your HEC-RTS watershed. Below are some common examples.

Rain vs No Rain Comparisons

You might want to compare watershed response and operational decisions with and without forecasted precipitation:

No Rain Scenario (observed conditions only)

  1. HEC-MetVue - no QPF
  2. HEC-HMS - normal conditions
  3. HEC-ResSim - normal operations

With Rain Scenario (forecasted conditions)

  1. HEC-MetVue - with QPF
  2. HEC-HMS - normal conditions
  3. HEC-ResSim - normal operations

Snowmelt Modeling

In regions where snowmelt significantly affects runoff, a forecast run tailored to snowmelt is necessary:

  1. HEC-MetVue - includes precipitation and temperature grids
  2. HEC-HMS - snowmelt alternative
  3. HEC-ResSim - normal operations

Different Precipitation Forecast Sources

You may want to evaluate how different QPF sources impact watershed response:

Scenario A - QPF from source A

  1. HEC-MetVue - QPF from source A
  2. HEC-HMS - normal conditions
  3. HEC-ResSim - normal operations

Scenario B - QPF from source B

  1. HEC-MetVue - QPF from source B
  2. HEC-HMS - normal conditions
  3. HEC-ResSim - normal operations

Estimating Flood Damage Reduction

If you are interested in assessing flood damages prevented by a reservoir or levee project during a storm:

  1. HEC-MetVue - observed precipitation
  2. HEC-HMS - normal conditions
  3. HEC-ResSim - normal operations
  4. HEC-RAS - with project features
  5. HEC-RAS - without project features

Additional Resources

Refer to this guide for step-by-step instructions on creating, editing, and deleting forecast runs in your HEC-RTS watershed.