Welcome to the RAS Solution › Forums › HEC-RAS Help › Computation error Minimum error exceeds allowable tolerance

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  • April 8, 2017 at 11:10 am #6412
    Anonymous
    Guest

    HI, could anyone help me with this problem?

    I run unsteady flow simulation and the program show the computation message
    Performing Unsteady Flow Simulation HEC-RAS 5.0.3 September 2016

    **** ERROR: Solution Solver Failed ****

    Minimum error exceeds allowable tolerance at 11FEB2014 01:00:00

    kali surabaya 1 7.3000*

    **** The Model Has One Or More Error(s) ****

    Unsteady Flow Simulation Terminated

    Writing Results to DSS
    Finished Writing Results to DSS

    Reading Data for Post Process
    Simulation went unstable at: 11Feb2014 01:01:00

    Running Post Processor HEC-RAS 5.0.3 September 2016

    Finished Post Processing

    Stored maps were not written because the simulation did not complete.

    Computations Summary

    Computation Task Time(hh:mm:ss)
    Completing Geometry <1
    Preprocessing Geometry(64) <1
    Unsteady Flow Computations(64) <1
    Writing to DSS(64) <1
    Post-Processing(64) <1
    Complete Process 1

    ****
    What should I do ?

    November 28, 2017 at 5:47 pm #10485
    Anonymous
    Guest

    Hi,
    Did you find any solution for this problem. I am getting the similar kind of errors. Thanks

    December 1, 2017 at 2:05 am #10486
    cameron
    Participant

    The model stopped because the minimum error tolerance was exceeded. This could be caused by a number of things, incorrect time step, need for additional cross-sections, more ineffective flow areas.

    December 21, 2017 at 5:58 pm #10487
    Anonymous
    Guest

    thanks, model is running now but still it is showing warnings and errors related to WSEL? how to fix them or we can ignore it?

    December 21, 2017 at 8:00 pm #10488
    Anonymous
    Guest

    HEC-RAS writes errors and warnings in 1) the computation messages shown in the unsteady flow analysis window, and 2) under the cross-section results.

    When running an unsteady flow analysis, the WSEL errors shown under the compute messages don’t necessarily need to be addressed. The general guidance I have heard is that WSEL errors in the 0.1 to 0.3 range, or lower, are usually okay. However, that pertains only to the WSEL errors. Other errors and warnings may be written after the unsteady computations have been completed, but before the post processing begins. These are highlighted in red and should be addressed.

    Warnings in the cross-section results don’t always need to be addressed, but the errors should be.

    December 21, 2017 at 10:29 pm #10489
    Anonymous
    Guest

    Thanks for the answer. I still have following errors, it would be nice if you could explain/guide how to resolve them.

    Performing Unsteady Flow Simulation HEC-RAS 5.0.3 September 2016

    Maximum iterations of 20 RS WSEL ERROR

    27MAY2006 00:00:00 Upper Main Reach 1 415500.0 249.05 0.027

    ***** Warning! Extrapolated above Cross Section Table at: *****

    Upper Main Reach 1 from R.S. 464900.0 to 462600.0
    Upper Main Reach 1 from R.S. 462300.0 to 462125.7
    Upper Main Reach 1 R.S. 461536.1
    Upper Main Reach 1 from R.S. 460924.6 to 457298.1
    Upper Main Reach 1 from R.S. 456896.6 to 454362.4
    Upper Main Reach 1 from R.S. 453618.5 to 452561.9
    Upper Main Reach 1 from R.S. 451953.4 to 449385.0
    Upper Main Reach 1 from R.S. 447410.4 to 446212.0
    Upper Main Reach 1 from R.S. 445626.5 to 445443.3
    Upper Main Reach 1 from R.S. 445031.9 to 442255.0
    Upper Main Reach 1 from R.S. 441681.5 to 440492.1
    Upper Main Reach 1 R.S. 439917.8
    Upper Main Reach 1 from R.S. 437907.4 to 437673.5
    Upper Main Reach 1 R.S. 436905.4
    Upper Main Reach 1 from R.S. 435119.1 to 434909.1
    Upper Main Reach 1 from R.S. 434099.6 to 433709.1
    Upper Main Reach 1 R.S. 433364.2
    Upper Main Reach 1 R.S. 432535.3
    Upper Main Reach 1 from R.S. 415869.3 to 415828.3
    Upper Main Reach 1 R.S. 410250.9
    Upper Main Reach 1 from R.S. 407949.4 to 407754.0
    Upper Main Reach 1 from R.S. 407200.6 to 407156.4
    Upper Main Reach 1 R.S. 406200.0
    Upper Main Reach 1 R.S. 406082.0
    Upper Main Reach 1 R.S. 404631.2
    Upper Main Reach 1 from R.S. 395179.0 to 395144.0
    Upper Main Reach 1 R.S. 395076.9

    The maximum xsec wsel error was 0.088
    Upper Main Reach 1 415500.0 at 27MAY2006 00:00:00

    **** The Model Has One Or More Warning(s) ****

    Thanks 🙂

    December 21, 2017 at 11:05 pm #10490
    Anonymous
    Guest

    The extrapolation warnings mean that the maximum WSEs were calculated to be greater than the maximum elevation applied to the hydraulic property table that corresponds to each cross-section listed under the warning.

    This can be corrected by manually increasing the maximum elevations in the HTab Parameter table editor in the geometry file.

    December 25, 2017 at 6:47 pm #10491
    Anonymous
    Guest

    Hi, i tried with different values in Htab parameters ( i simply increase the ‘increment’ tab value, is this the right way?) along with it there are still some warnings in the cross-sections. Few of them are listed below. Can you please explain which if them i need to address and how?

    Location: River: Upper Main Reach: Reach 1 RS: 463300.0 Profile: Max WS
    Warning: The cross-section end points had to be extended vertically for the computed water surface.
    Location: River: Upper Main Reach: Reach 1 RS: 463200.0 Profile: Max WS
    Warning: The cross-section end points had to be extended vertically for the computed water surface.
    Location: River: Upper Main Reach: Reach 1 RS: 463100.0 Profile: Max WS
    Warning: The cross-section end points had to be extended vertically for the computed water surface.
    Location: River: Upper Main Reach: Reach 1 RS: 463000.0 Profile: Max WS
    Warning: The cross-section end points had to be extended vertically for the computed water surface.
    Warning: The conveyance ratio (upstream conveyance divided by downstream conveyance) is less than 0.7
    or greater than 1.4. This may indicate the need for additional cross sections.
    Location: River: Upper Main Reach: Reach 1 RS: 462900.0 Profile: Max WS
    Warning: The cross-section end points had to be extended vertically for the computed water surface.
    Warning: The conveyance ratio (upstream conveyance divided by downstream conveyance) is less than 0.7
    or greater than 1.4. This may indicate the need for additional cross sections.
    Location: River: Upper Main Reach: Reach 1 RS: 462800.0 Profile: Max WS
    Warning: The cross-section end points had to be extended vertically for the computed water surface.
    Warning: The energy loss was greater than 1.0 ft (0.3 m). between the current and previous cross section.
    This may indicate the need for additional cross sections.
    Location: River: Upper Main Reach: Reach 1 RS: 462700.0 Profile: Max WS
    Warning: The cross-section end points had to be extended vertically for the computed water surface.
    Warning: The energy loss was greater than 1.0 ft (0.3 m). between the current and previous cross section.
    This may indicate the need for additional cross sections.
    Location: River: Upper Main Reach: Reach 1 RS: 462600.0 Profile: Max WS
    Warning: The cross-section end points had to be extended vertically for the computed water surface.
    Warning: The conveyance ratio (upstream conveyance divided by downstream conveyance) is less than 0.7
    or greater than 1.4. This may indicate the need for additional cross sections.
    Location: River: Upper Main Reach: Reach 1 RS: 462500.0 Profile: Max WS
    Warning: The cross-section end points had to be extended vertically for the computed water surface.
    Location: River: Upper Main Reach: Reach 1 RS: 462400.0 Profile: Max WS
    Warning: The cross-section end points had to be extended vertically for the computed water surface.
    Location: River: Upper Main Reach: Reach 1 RS: 462300.0 Profile: Max WS
    Warning: The cross-section end points had to be extended vertically for the computed water surface.
    Warning: The velocity head has changed by more than 0.5 ft (0.15 m). This may indicate the need for
    additional cross sections.
    Warning: The conveyance ratio (upstream conveyance divided by downstream conveyance) is less than 0.7
    or greater than 1.4. This may indicate the need for additional cross sections.
    Location: River: Upper Main Reach: Reach 1 RS: 462125.7 Profile: Max WS
    Warning: The cross-section end points had to be extended vertically for the computed water surface.
    Warning: The velocity head has changed by more than 0.5 ft (0.15 m). This may indicate the need for
    additional cross sections.
    Warning: The energy loss was greater than 1.0 ft (0.3 m). between the current and previous cross section.
    This may indicate the need for additional cross sections.

    Thanks again for your suggestions.

    May 9, 2018 at 5:55 am #10492
    Anonymous
    Guest

    Hello Mohsin, i’m Dhiya from Indonesia. I have problem that same with you, have you solved that problem? Because i was change htab parameters, but still error like that. Thanks for your attention.

    February 16, 2019 at 12:39 am #10493
    CJones
    Participant

    Sooooo what did you do to get it running?

    April 13, 2019 at 2:30 pm #10496
    Anonymous
    Guest

    In Computational setting keep the Computational interval as minimum as possible to remove all the errors

    June 20, 2019 at 8:10 pm #10494
    sajna94
    Participant

    Ineffective flow area means??

    September 19, 2019 at 10:20 am #10495
    Anonymous
    Guest

    Hy I am facing the same issue but every time I ran the simulation.The error highlighted differemt crossection each time

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