US Army Corps of Engineers
Hydrologic Engineering Center

Skip Navigation LinksHome > software > hec-ressim > whats new


Version 3.1 of the Reservoir System Simulation (HEC-ResSim) software is now available. This version supersedes Version 3.0, which was released in April 2007 to the general public, and all previous versions. Several new features, as well as enhancements to existing features, have been added to the software since that time. Version 3.1 of HEC-ResSim includes the following new features and enhancements (each item includes a reference to the HEC-ResSim User's Manual for detailed information):

New Features

  1. Variable Lag & K Routing Method (Section
  2.   The Lag & K method is a hydrologic storage routing method that is based on a graphical routing technique   that is extensively used by the National Weather Service (NWS) in their forecast modeling tools.

  3. Variable Power Plant Capacity (Section 10.17.2)
  4.   The installed power capacity at a power plant can be entered as a constant MW value (along with an   overload Factor), or as a variable power capacity that is a function of: Reservoir Elevation, Reservoir   Storage, Release, or Operating Head.

  5. Flexible Zone Definition (Section 11.3.3)
  6.   A reservoir operating zone can be defined as a function of: Date, Date & Time, Model Variable, External   Variable, or State Variable.

  7. Flow Contingency for Downstream Operation (Section 11.5.4)
  8.   For downstream operations, a flow contingency percentage can be applied to the cumulative local flows at   the downstream location. This contingency value can be entered as either a constant or as a function of   the downstream location's cumulative local flows.

  9. Advanced Options for Downstream Operation (Section 11.5.4)
  10.   For downstream operations, two adjustments can be made that impact the reservoir release decision   process: (1) how routing attenuation is considered; and, (2) how rate-of-change rule constraints are   handled. These adjustments can be applied globally (to all downstream rules at all reservoirs) or can be   applied differently to individual rules.

  11. Induced Surcharge ESRD Curves (Section
  12.   Emergency Spillway Release Diagram (ESRD) curves can be entered as an "Elevation versus Minimum   Release per Inflow" relationship or as an "Elevation versus Minimum Release per Rate of Rise" relationship.

  13. Induced Surcharge Failing Pool Release Option to Maintain Peak Gate Openings (Section
  14.   This option calls for the falling pool release (the drawdown releases controlled by the induced surcharge   rule) to reflect the "current" capacity of the outlets at the "gate opening" they had when the peak release   was reached.

  15. Projected Elevation Operation (Section 11.12)
  16.   With this feature on, HEC-ResSim will compute the elevation the pool will reach after the user-specified   number of hours assuming that the current release is held over that period. A sub-option of this feature, if   selected, causes the active operating zone to be selected based on the projected pool elevation rather   than the current elevation.

  17. Alternative Editor - Run Controls (Time Step & Flow Computation Method) (Section 13.4)
  18.   From the Run Control Tab of the Alternative Editor, the user will need to select a Compute Time Step
      (ranging from 5 minutes to 1 day) and choose a Flow Computation Method (i.e., Program Determined,   Period Average, Instantaneous) to indicate the appropriate method to be used in the computations.

  19. Alternative Editor - Time Series (Plot & Tabulate DSS data; Inflow Multipliers) (Section 13.8)
  20.   From the Time-Series Tab of the Alternative Editor, the user can review the data values in a DSS record in   graphical or tabular form. The user can also use Inflow Multipliers to increase and/or decrease the   incremental local flows. These multipliers can be used globally or by location.

  21. Alternative Editor - Hotstart Capability (Section 13.10)
  22.   From the Hotstart Tab of the Alternative Editor, you can Create and Load Hotstart Files. Basically, this   feature can be used in place of the Lookback period data to establish the initial system state (i.e., use a   previously simulated watershed state to another alternative or simulation).

  23. Simulation Run Manager (Section 14.1.1)
  24.   This option provides the user with the capability to select and compute multiple alternatives in a simulation.   The user can also select and view the compute logs for each alternative.

  25. Storage (or Elevation) Overrides (Section 14.6.3)
  26.   Forces the reservoir storage (or elevation) to be values specified by the user. Specifying these override   values can disrupt mass balance computations; therefore, you must use caution when using this   override option.

Other Enhancements & Improvements

  1. Capability to turn on/off the Grid Lines in the Map Display region (Section 2.2.1)
  2. Network Connectivity Tool (Section 8.1.3)
  3. Import Network (Section 8.2.3)
  4. Simulation List (a list of the current simulations and alternatives available, along with their last compute times) (Section 14.1.1)
  5. New Compute options to "Save GC Releases to DSS" and "Consider ROC rules during Downstream operation logic" (Section 14.4.2)

 We strongly recommend that before using HEC-ResSim 3.1:

           Make backup copies of existing watersheds (and consider having
            separate modeling locations for Versions 3.0 and v3.1 watersheds)

As you use HEC-ResSim Version 3.1:

1) check the data in all elements of your model, being especially vigilant in reviewing your operations rules

2) verify the operation of your current models with HEC-ResSim Version 3.1, and

3) once satisfied with the results produced by the new version for each of your current models, make another set of backup copies. This second backup copy is suggested because when you open a watershed in HEC-ResSim Version 3.1, the format of key model files is changed, potentially making the watershed unable to be opened with older versions of HEC-ResSim.