HEC-WAT has multiple types of plugins that provide a variety of useful features. There are two main types of plugins that are important to note and discuss that pertain to the computation of results in HEC-WAT:

  • Computable plugins
  • Hydrologic Event Generator plugins

Computable plugins can participate in the program sequence within an HEC-WAT simulation, meaning that they can be linked to other models, compute results, and may produce output variables. All plugins that participate in the program sequence in a WAT compute are considered computable plugins.

Hydrologic Event Generator plugins are a specific subset of computable plugins. They support the FRA Compute type in HEC-WAT by providing the list of hydrologic events in an FRA simulation. 

The following computable plugins are provided with the installation package for HEC-WAT: 

Hydrologic Sampler

The Hydrologic Sampler plugin can generate system-wide hydrologic events for a Flood Risk Analysis compute, or Monte Carlo simulation. The outputs produced by the Hydrologic Sampler plugin can take the form of flow hydrographs or rainfall hyetographs spanning the analysis period selected for the simulation. This is a Hydrologic Event Generator plugin.

Stochastic Data Importer

The Stochastic Data Importer plugin is used to import user defined hydrologic data generated externally to HEC-WAT intended to be computed as events in an FRA compute, including both flow hydrographs and rainfall hyetographs. The Stochastic Data Importer plugin is only available for use during a Flood Risk Analysis compute. This is a Hydrologic Event Generator plugin.

Time Window Modifier

The Time Window Modifier plugin allows the user to change the time window computed by the Hydrologic Event Generator plugin (Hydrologic Sampler or Stochastic Data Importer). The time windows can be lengthened or shortened, and the Time Window Modifier  is typically used to shorten time windows to reduce computational burden for more complex models like HEC-RAS. The Time Window Modifier plugin is only available for use during a Flood Risk Analysis compute.

Time Window Interval Generator

The Time Window Interval Generator plugin can be used in a deterministic compute to break a multi-year continuous simulation into segments that are 1 year in duration.  This is useful to support continuous simulation in some plugins higher in the program order, and annual sub-timewindows for other plugins lower in the program order. The Time Window Interval Generator plugin is only available for use during a deterministic compute.

Scripting 

The Scripting plugin allows the user to write a Jython script to perform customized actions during the compute sequence.

Fragility Curve Sampler

The Fragility Curve Sampler plugin supports random selection of both the probability and trigger elevation of failures at levee breach locations identified as part of an HEC-RAS model alternative. The Fragility Curve Sampler plugin is only available for use during a Flood Risk Analysis compute.

Performance Metrics 

The Performance Metrics plugin generates the following performance and economic results:

  • Assurance
  • Annual Exceedance Probability
  • Long-Term Exceedance Probability
  • Expected Annual Damage

The Performance Metrics plugin is only available for use during a Flood Risk Analysis compute.