BRCH-J

01 May 2018

Version 2-0-0 of the Breach Erosion Model (BRCH) is available for release.  The Metric Option has been added to the model, and several bugs were fixed.  Some changes made to this version may result in noticeable changes when compared to the last NWS version (1999).  This is due to corrections made as stated below.  These noticeable changes in the model output are also found when comparing BRCH Version 1-0-0 (2010) to BRCH Version 2-0-0 since the results were the same between NWS BREACH and the previous version of BRCH (Version 1-0-0).  BRCH Version 2-0-0 has been extensively tested using over 50 datasets, and is more robust than any version of the BREACH since its development.

Version 2-0-0 of the BREACH GUI (BRCH-J) is also available.  The animation views in the output component of the BREACH GUI has been overhauled to better reflect the BREACH application’s representation of a breach failure.  In 2010, the BREACH GUI (BREACH-J) was released as developed at NWS.  Major changes were made to the GUI; however the results were not impacted except for the changes in the animation views as noted below.  Since it is not affiliated with NWS, the name of the latest version of the GUI (2-0-0) has been changed to BRCH-J to be consistent with the BRCH application.  BRCH-J was extensively tested using the BRCH datasets and is more robust than version developed at NWS.

BRCH-J is available for both Windows and Linux operating systems.

Changes to the BREACH Model (BRCH 2-0-0)

The following changes have been made to the FORTRAN code since the 2010 release version.

  • Surface Area vs. Elevation Table – There was a bug in the code when the table had eight values.  There was also a problem when the table had less than 8 values and the water level was below the minimum elevation.  The spillway flow was half of what it should be.  This bug was fixed by assigning a size (nhsa) to the table array, and the correct flow is computed.
  • Top Width vs. Elevation Table – The table values may not have been addressed properly because of a coding flaw when all eight values are used, and when fewer than eight values were read in but the water level was beyond the range of the table.  This bug was fixed by assigning a size (ncs), and the computed cross section properties are correct.
  • Maximum Breach Bottom Width – The maximum breach width is set to the crest length whenever a negative value is computed.
  • Computed Tailwater Elevation (TWD) – The tailwater elevation was not computed when the reservoir was in fill mode (KG = -1).  The code has been modified to allow the tailwater elevation to be computed if there is spillway flow.  Also the algorithm to compute the tailwater elevation under all conditions was enhanced.
  • Piping Failure Algorithm Changes – An error was found in the computation of the breach length (PPP) depth of breach (HP) after a piping breach collapse.  Although these changes result in more accurate computations of the parameter, there is little change in the peak outflow.  Also, the reservoir is allowed to fill if the water level is below the bottom of the breach. 
  • Time Step Limits – The minimum computation al time step (DTH) is set to 0.0001.  The maximum time step for reservoir filling (DTHFIL) is set to 0.5.  If the inflow hydrograph is steady-state, the DTHFIL=0.5.
  • Average Internal Friction Angle (AFRA) – This parameter prints out correctly.  It was erroneously printing out a value of zero.
  • Metric Option – The input/output may be displayed in metric units.  The input parameters are in metric units and converted to English units.  The computations are done in English units, but all output information, including debug information, is done in metric units.
  • gFortran90 Compiler – The code was modified to be gFortran90 compliant.  This includes initializing parameters, changing read/write statements and formatting.  These changes caused several data sets to run to completion which previous would not run.
  • Cosmetic Changes – Headings were added to the debug output.  The format fields and spacing were increased in the output table.

Changes to the BREACH GUI (BRCH-J 2-0-0)

The following changes were made to the BREACH GUI since the 2010 release version.

  • Metric Option – The input and output may be displayed in metric units.
  • Failure Regions – All failure regions (KG) are included in the animation.
  • Animation – The animation views in the output component of the BREACH GUI has been overhauled to better reflect the BREACH application’s representation of a breach failure.  The water surface is allowed to attenuate throughout the breach opening.  Backwater affects are also represented.  The previous version assumed a horizontal water surface throughout the breach opening.