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Version 2 Build Update

The Current Release is:

MIDUSS Version 2
2.25 Rev 468

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To find out your current version while running MIDUSS, click the Help / About menu item.

MIDUSS has been under development since the mid-1980s and we are continually making improvements. 

The first MIDUSS was used on DOS systems and progressed to version 4.72.1. 

MIDUSS was completely rewritten for the Windows operating system and on Sept. 4, 1998 MIDUSS 98 was released. 

On Feb. 8, 2004 we released our current MIDUSS Version 2.

There have been 27 updates since the release.  These are documented below.

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Known issues we are
working on correcting
for the next update.


2.25Rev468 March 6, 2009
  • A error has been corrected in the POND command. In defining a pipe as an outflow control the special case of a pipe that is hydraulically steep the discharge was wrong for diameters less than 1.0ft or 1.0m. This has now been corrected.
  • In the Pond Design the routine to compute outflow from one or more outflow pipes gave exaggerated flow values when used with a pipe that was hydraulically steep (i.e. Yo<Ycr). This was caused by the assumption of outlet control when in fact inlet control occurs with critical flow at entry. The routine has
    been revised to correctly compute outflow values under inlet control when the physical slope exceeds the critical slope. It should be noted that the critical slope varies slightly with the stage of the flow. Users are advised that supercritical flow in the outflow pipe of a pond may result in a hydraulic jump with
    unpredictable results.
  • In the Pond Design option an error occurred when using CSPA sections as Superpipes. This has been corrected.
  • With the “Show/Output File” command MIDUSS previously checked the size of the file to decide whether to use NotePad or WordPad. With more recent versions of NotePad this is no longer necessary and has been abandoned.
  • After using the Pond command to design a normal detention pond, a subsequent use for rooftop storage was initialized showing the old starting water level. This has now been corrected.
2.25Rev465 Feb 5, 2008
  • In the Pond Design command a number of minor changes have been made to improve accuracy by increasing the number of significant figures defining H, Q and V data imported from the Input file when running in Automatic mode. Users will see data in formats adjusted to suit the magnitude of the value.
  • Code in the IDF Curve Fit tool has been modified to trap an error when the Storm number is not defined.
  • In the Catchment command the computed runoff coefficient for the Impervious fraction of an area with less than 100% impervious surface was slightly different from that in a catchment that is 100% impervious. This has been corrected. Only the Impervious Runoff coefficient in the [Show Details] display is changed; the Runoff calculations are not affected.
  • Two minor changes have been made to the Trench design command. The maximum infiltration areas on the sides and base of the trench are reported in the output file. Also, the Outflow controls menu item has been modified to show the type and number of the weir, orifice and outflow pipes are displayed to assist users who wish to delete a previously defined control.
  • In the Trench design command the routing process was sometimes numerically unstable particularly with inflow hydrographs that are very ‘peaky’, such as runoff resulting from a Chicago design storm. The routing time step has been reduced to reduce this problem.
  • In the modification Rev462 the computed time of the true peak in the warning message was too large by one time-step. This has been corrected.
2.25Rev462 June 15, 2007
  • With Revision 451 use of a comma or a period as the decimal separator is possible. However, with this change a single decimal separator caused an error since this is not a legal string. All data entry text boxes have been modified to trap a single decimal and convert it to ‘0.’ Thus allowing easy entry of values less than 1.
  • The IDF Curve Fit tool has been modified to allow a file of results to be created with comma separated variables to allow import of the results to a spreadsheet such as Microsoft Excell. Users of this feature are invited to submit suggestions to improve the format such as adding logarithmic values.
  • In the Pond Design feature the routing time step must often be a sub-multiple of the user defined time step to ensure numerical stability. In such cases it sometimes happens that the maximum outflow at a routing time interval is slightly greater than the peak flow at a regular time-step. In Revision 458 (March 3, ’07) the higher value was reported in both the Peak Flows summary table and the Output file resulting in some confusion. This has been corrected and the user is informed by a short message on the Pond window
2.25Rev458 March 12, 2007
  • In the Pond Design further modifications have been made to the Split Outflows menu item to enable the menu item when more than 2 Outflow Controls have been defined and also to correctly remove outflow devices (eg replace 2 orifices with 1 orifice and 1 weir).
  • In the Pond Design feature two small corrections have been made. In the tabular display of the Outflow hydrograph, changing the number of decimal places caused the wrong flow values to be displayed. Also when plotting a graph of discharge Q as a function of volume V pressing the primary mouse button to display the numeric values in the window title showed the wrong discharge. Both of these errors have been corrected.
  • In the Pond Routing procedure the routing time step is set to a small sub-multiple of the user-defined time step to ensure numerical stability in the vicinity of a very nonlinear stage discharge function. In extreme cases this resulted in an overestimate of the outflow volume. In such cases a warning is now displayed and a correction to the stored volume is made.
  • In the Pond and Trench design commands a minor change has been made to correct an error which caused the displayed Hydrograph Volume value to be rounded up to the next multiple of 10.
  • In the Culvert and Pond design routines, calculation of the stage discharge curve has been modified slightly to make the curve more consistent for the two cases of designing a culvert and using a culvert as an outflow control from a pond.
  • Code has been modified in all routines using a grid to automatically detect and correct errors caused by user entry of an illegal string – e.g. numbers with two decimal separators (period and/or comma).
  • In the IDF CurveFit tool an error has been corrected when running in Automatic mode. This error was the result of the change described in Revision 451. In addition, code has been modified so that results obtained in Automatic mode are now identical (or very nearly so) to those obtained in Manual mode. This was caused by rounding error in computed values of either depth or intensity of rainfall.
  • A update has been completed in which the decimal separator can be both a comma and a period. This was done for the benefit of users who defined the Locale as French or any other language employing a comma separator. However, for added convenience code has been modified to allow either Key (i.e. ‘.’ or ‘,’) to be used and the symbol is converted if necessary into that used by the User locale.
  • In the Design/Pond command the Outflow Control menu items have been modified to indicate which outflow types are currently in use and also the number of such devices. This is a cosmetic addition for the convenience of users.
    Also in the Pond command an error has been corrected to reduce the number of outflow devices each time an outflow control is deleted.. This affected use of the Pond command <Split Outflows> which separates the total outflow hydrograph into separate components. The <Split Outflow> has been slightly modified to allow the outflow to be split when 2 or more of the same type of outflow control are defined (e.g. if only 2 orifices are used).
  • In the Hydrology/Catchment/ command a few changes have been made to correct errors when using the Green Ampt infiltration option. The runoff coefficient values displayed when the [Runoff Details] button is pressed are now correct, and the entered value of Soil Moisture Deficit entered under the /Pervious\ tab is no longer defaulted to zero after the runoff is calculated.
  • In the Trench command an error in the display of the total storage volume has been corrected. This does not affect the volumes used or the results obtained.
2.20Rev414 October 27, 2006
  • In the Pond Design command the use of Pipes with a positive slope as an outflow control gave different results in Automatic mode compared to Manual mode (e.g. using menus). This has been corrected. Also in the Pond Design command the routine to compute the outflow from a Pipe with a negative (adverse) slope has been improved.
  • The Client Network program MIDUSSNet.exe has been improved to trap and correct errors when a client user selects MIDUSSNet.exe instead of MIDUSS.exe when navigating to the Server. This update is of interest only to MIDUSS Network administrators.
  • In the Hydrograph/Edit Inflow/ command, elements of very long hydrographs (e.g. with more than 13330 values) could not be edited. This has now been corrected.
2.20Rev413 August 9, 2006
  • In the Trench command the modification noted on March 23, 2006, Revision 406 was found to introduce errors in the calculation of the maximum storage. The code prior to that date has been restored.
  • The Pond command has been corrected to avoid an error in the computed lag time which occurred when a constant base-flow was added to the Inflow hydrograph
  • Users of Windows XP or Windows 2000 may use a MIDUSS data folder name that is very long (e.g. C:\Documents and Settings\User Name\My Documents\MIDUSSdata\My Latest Job\...) and may encounter run time errors if the path name contains more than 130 characters. This has been modified to allow very long names although with a poorly formatted header in the output file.
  • Due to the popularity of USB ‘Memory sticks’ users have encountered a “Path not found” error when the last-used Output folder is removed prior to the next session. This error is now trapped and the default output folder is set to either \MIDUSS\ or \MIDUSSNet\.
  • In the Status form code was modified to handle unexpected conditions in the Registry.
2.20Rev408 April 13, 2006
  • When using the File/Load/… menu command to load a storm hyetograph or a flow hydrograph, the table displayed when the [View] command button is pressed did not show the time of a cell when the mouse pointer hovers over the cell. This has been corrected.
  • A number of files have been added including four message box icons and two storm files describing the Ontario regional storm Hazel for durations of 12 and 48 hours.
2.20Rev407 March 31, 2006
  • In the Trench command code has been modified to improve the calculation of required volume and the accuracy of the flood routing algorithm.
  • In the Culvert design command the plotting routine has been modified to ensure that the minimum line thickness is 1 pixel.
  • This revision allows Client users of the Network version to automatically copy typical files of Reg-U-Flo Vortex Valves from the server.
  • Through a cooperative agreement with Hydro International this major upgrade includes addition of Reg-U-Flo Vortex Valves as outflow controls for detention ponds. This includes a new Tools/Make Vortex Valve feature that allows users to design a customized Reg-U-Flo Vortex Valve for any desired throat diameter or flush discharge. See Lessons 24, 25 for more details.
  • In the Pond design closing the form with the [Accept] command button did not clear all the data associated with the Horizontal Orifice outflow control (when the ‘Keep all design data’ checkbox was unchecked). This has been corrected.
  • Under certain conditions MIDUSS failed to open properly due to a name change in the LogFile. This has been corrected.
2.07Rev387 September 23, 2005
  • In the Cascade design the initial conditions were previously computed for the first element of the Inflow hydrograph. This has been corrected to represent a starting condition of zero flow.
2.07Rev386 August 11, 2005
  • In the Pond command if more than 4 items of the same type (e.g. Orifice, Superpipe etc.) were defined the grid displayed a vertical scroll bar to access all items. This has been improved to allow the form to be extended downward by dragging the lower edge to show an expanded grid.
  • In the <Pond/SuperPipe> command, code previously caused the manhole area to be multiplied by the number of barrels. When more than one barrel was used this caused the volume above the barrel obvert to be too large. This error has been corrected. The error did not affect results except when the barrels were surcharged.
2.07Rev384 July 19, 2005
  • When using the <File/Save/Hyetograph> command in Automatic mode with an output file created with Version 1 (Miduss98) inconsistent code caused the following command to be skipped. This error has been corrected.
  • When using the Pond command with a circular Superpipe (i.e. a pipe) a cosmetic error caused the Pipe ‘width’ in the output file to not correctly reflect user editing of the diameter. Calculations of volume were not affected. The error has been corrected.
  • When running in Automatic mode, use of the Hydrology/Lag and Route command caused the previous Catchment form to be re-displayed. This has been corrected.
  • Code in the Pond command has been modified to allow easier recovery if use of the [Route] button causes a “Range Too Small” warning to be displayed.
  • When using a Culvert as the outflow control for a detention Pond the vector of discharges Q in the H-Q-V grid of the pond form changed because interpolation was done using a stage-discharge curve based on the peak outflow rather than the peak inflow. This has been changed to produce a consistent column of Q values. The change also causes the stage-discharge curve in the <Design/Culvert> command to be unchanged between the [Design] stage and the [Route] operation.
2.07Rev382 June 23, 2005
  • When using the Chicago option in the Storms command, MIDUSS positions the interval of peak intensity between times defined by (R.Duration – R.dT) and (R.Duration + (1-R).dT). This means that the peak intensity is sensitive to the fraction R. A check box has been added that causes the fraction R to be adjusted automatically to produce a maximum intensity equal to A/(dT + B)^C.
  • When using the <Outflow Control/Culvert> menu option in the Pond command code has been modified to ensure that the [Route] button is enabled if volumes are entered manually in the H-Q-V grid. Also, some units have been corrected when running in Imperial (U.S. Customary) units.
  • In the POND command multiple items (up to 10) can be defined for geometric and outflow comtrols. Previously, only 4 rows were displayed and other rows could be accessed using a vertical scroll bar. This has been improved to cause both the form and the grid to expand or contract automatically to show all items.
  • In the POND command underground storage can be defined by using the ‘Geometry/Superpipe’ menu item and selecting the required cross section. An error has been corrected that caused the ‘Box’ cross-section to act as an open-topped rectangular cross-section.
2.07Rev379 March 28, 2005
  • When MIDUSS is run for the first time it tries to create a folder \MIDUSSdata\ in which the user may store output data. The code has been modified to allow this to be done when the Logon User Name contains Double Byte characters (DBCS) such as in South-East Asia languages.
  • In the Pond command if the range of depth, storage or discharge was insufficient to route the inflow hydrograph and the user changes the design and tries [Route] a second time, an ‘Invalid Row’ error occurred if the “Extend WL Range” was not checked. This error has been corrected.
  • This release fixes (via a new Setup.exe) a recently introduced bug which prevented the user from selecting a custom destination folder for the MIDUSS program files.
2.07Rev375 March 2, 2005
  • When MIDUSS is being installed for the first time, a recently introduced error in the MIDUSS Status form caused the expiry date of available maintenance to be incorrect. The error appears to have been introduced since Revision 367. It has now been corrected
2.07Rev374 February 23, 2005
  • In the Pond command the user can choose to define a starting water level that is lower than the minimum invert level in the defined Outflow controls. However, if the total inflow hydrograph has a volume less than the storage volume corresponding to the minimum invert level the peak outflow is zero but the maximum water level and storage were often incorrectly interpolated. This has been corrected by interpolating in terms of volume rather than outflow.
  • In the Storm command the Mass Rainfall Distribution option can use an *.MRD file that resides on storage device (e.g. hard disk) on a networked computer or server. If the resulting output file is used to run in Automatic mode on a computer that does not have access to the device a fatal error occurred. This error is now trapped thus giving the user the opportunity to Browse for the required file.
  • Cosmetic changes made to Status form to avoid confusion between Serial numbers of different types.
  • In the help About form dates 2004 updated to 2005.
  • The <Hydrograph/Copy Inflow to Outflow> command has been enhanced to prevent the command from being used if the Inflow hydrograph has been already used for another purpose.
  • When using the Layout feature, certain versions of the Windows operating system change the name of a hydrograph file to lowercase. This resulted in the link between the Diversion icon and an imported Diversion hydrograph to be lost. This has been corrected.
  • Running in Automatic mode with a changed storm descriptor, saving a hydrograph file with the new extension failed if the original file name in the input database contained neither an extension nor a terminating period. This has now been corrected.
  • In the Tools/IDF CurveFit command code has been corrected to display the correct units when running in Imperial/Customary US Units mode. Also, a non-fatal display of an error message has been made more explanatory. Both changes do not alter the computed results.
  • A non-fatal error in the Layout procedure has been corrected. The error occurred in the unlikely case that the Hydrograph/Add Runoff command was used twice or more in succession.
  • Code has been added to implement a hardware security device for those distributors of MIDUSS who require this capability.
2.07Rev366 January 26, 2005
  • A number of improvements have been made to the Culvert command:
    • When a channel is defined before using the Culvert command the channel geometry parameters for both trapezoidal and complex channel cross-sections is imported even if other commands (e.g. Catchment) have been used between the Channel and Culvert commands.
    • In Automatic mode the full descriptions of the contraction coefficient Cc and energy loss coefficient Ke are displayed in the drop-down boxes.
    • When the Culvert command is invoked as an Outflow control in the Pond command the resultant stage-discharge data can be removed by use of the [Cancel] command button on the Culvert window.
2.07Rev365 January 14, 2005
  • Messages displayed from the opening Status window have been modified to assist first time users.
  • The IDF Curve Fit tool has been improved to (i) to work with the Save Session and Load Session commands, (ii) to copy the return interval (ARI) to the storm description when the IDF coefficients are copied to the Storm command, (iii) to automatically display the data for the last referenced storm when the IDF tool is invoked for a second (or greater) time or after a Load Session command and (iv) avoid ‘log zero’ errors in the IDF graphing tool.
2.07Rev364 January 10, 2005
  • The IDF tool has been corrected to ensure that multiple storms (2 to 5) are retained for use during the current MIDUSS design session.
  • The File/Save Session command has been modified to avoid a run-time error if Layout plotting is enabled but zero objects have been plotted on the Layout when the session is saved.
  • In the Culvert command code has been added to re-calculate the weir flow and maximum water level when the [Route] command is used on a culvert that is sufficiently surcharged to overtop the embankment. The display of results both on the form and in the output file has been improved.
2.07Rev360 December 29, 2004
  • The Tools menu has been extended by the addition of the Swinburne method for the approximate determination of the Site Storage that should be provided to compensate for the urbanization of a sub-catchment within an undeveloped watershed. The method is available only to Malaysian users as it is one of the methods recommended in the Urban Stormwater Management Manual for Malaysia (Dept. of Irrigation & Drainage Malaysia, 2001). A description can be found at the following web site:
    Currently this tool can be used only with Metric (S.I.) units.
  • In the Show/Layout command if the user changed the plotting quadrant from North to South or vice versa (e.g. from SE to NE or NW or from NE to SE or SW) and then defined a new tributary with the Hydrograph/Start New Tributary command the first object was plotted out with the visible quadrant. This error has been corrected.
  • Following the combination of the Culvert outflow control in the Pond design (Revision 354 December 8) an error in the Culvert [Route] command was identified and has been corrected.
2.06Rev355 December 14, 2004
  • In the ‘Tools/Time of Concentration’ menu item two additional empirical methods have been added for the estimation of wave travel time on the overland flow segment of a drainage path. These are for the Airport (or FAA) method and the Bransby-Williams method as recommended by the Ontario Ministry of Transportation (MTO). The equations for the Kinematic and Friend methods have been modified slightly to show the coefficient values explicitly for Imperial and Metric (SI) units.
  • The Pond command has been enhanced by the addition of a Culvert control to the list of other Outflow Controls (e.g. Weir, Orifice, Horizontal Orifice and Pipe). This option causes the Culvert form to be displayed with initial data based on the minimum and maximum water levels defined for the Pond. One or more barrels can be specified in any of the five cross-section shapes (pipe, box, elliptical pipe & pipe arch). Pressing the [Design] button on the Culvert form causes the stage discharge data (Q=f(H)) to be exported to the Pond form reflecting changes from Inlet control to Outlet control etc.
    Additional controls can be defined as required and the inflow hydrograph routed through the facility. An accepted design can be processed in Automatic mode as usual.
    A new Tutorial lesson on the use of the new control has also been prepared will be available on the web-site and with the program.
  • When running the Pipe command in Automatic mode a condition of surcharge caused two warning messages to be displayed twice – annoying but not fatal. This has been corrected.
  • In the Culvert command the code to compute the conjugate depth in a closed conduit (pipe, box, elliptical pipe & pipe arch) was modified to remove the possibility of cycling when the depth downstream of the hydraulic jump is greater than the depth of the conduit.
2.05Rev349 November 9, 2004
  • In the Catchment command the information displayed by the [Show Details] command button has been expanded to show the volumetric Runoff coefficient C for the pervious and impervious fractions as well as an area weighted average C for the total area. If changes are made to Catchment parameters while these details are displayed, relevant data is updated when the [Display] button on the Catchment Tab is pressed.
  • The Layout command has been updated to handle situations in which 2 or more sources of runoff (i.e. catchments or runoff hydrograph files) are clustered around a single node.
  • If a Catchment command is cancelled the previous runoff hydrograph is restored and the menu item Hydrograph/Add Runoff is enabled.
2.05Rev347 November 2, 2004
  • The Tools/IDF Curve Fit command has been improved to prevent the focus from shifting to the Symbol Size spin button when data is entered in the 3rd row of the Time-Depth-Intensity table.
  • When using the Files/Save Session command the user is warned that MIDUSS will Exit after the session file is saved. However, the Area Totals message gave the user an option to Cancel the exit. This has been corrected.
  • In the Trench command if no outflow controls are used a false warning message reported that the lowest invert level of an outflow device was above the top of the trench stone. This has been corrected.
  • In the Pond command, if the maximum water level was too low to route the current inflow hydrograph, MIDUSS attempted to extend the range to accommodate the peak inflow. A new checkbox labeled “Extend WL Range” has been added to the pond form to allow the user to turn this feature off or on. The initial default is ‘Off’ but the user’s preference is stored in the Registry option.
  • The Culvert command has been improved to show the slope values on the cross-section plot and provide a clearer warning message if the roadway Weir slope is steeper than or equal to the bank slope.
  • A number of changes have been made to the Culvert command and the associated plotting routines.
    • Calculation of weir flow has been refined to reflect different entry conditions.
    • Calculation of hydraulic jump conjugate depth in elliptical barrels has been improved.
    • An error in estimating upstream water level when the barrel is steep (Yo < Ycr) and the tail water depth is above the depth conjugate to the normal depth has been corrected.
    • Plotting of the gradually varied flow in the barrel is now based on the coordinates of the surface profiles in the barrel.
    • The profile plot now includes an option to display the hydraulic grade line in addition to the water
      surface profile and the normal and critical depths.
    • A [Tip] help button has been added describing how to use the various Dynamic Control data entry boxes. This greatly improves ability to observe sensitivity of the design to certain important variables.
2.04Rev336 Aug 12, 2004
  • The Storm command has been modified to allow Mass Rainfall Distribution (*.MRD) files to be stored in any folder instead of limiting this to the application folder.
  • An error has been corrected if the user chooses not to browse for an *.MRD file when the file name in the input database is not found.
  • In the Malaysian version, use of the ‘Storms (Malaysia)’ command in automatic mode now causes the ‘IDF(Malaysia)’ window to be regenerated and displayed. Data includes the 2year, 24 h rainfall depth required for storms of duration less that 30 minutes.
  • In the Malaysian version the ‘Storms (Malaysia)’ command now allows definition of very frequent storm events with ARI values of 1, 3, 6 months and 1 year.
  • In the Trench command the algorithm to estimate the required trench volume for a specified target outflow peak has been improved – particularly for very small target flows. The plot time for the hydrograph display is now set to a more reasonable value.
  • In the Pond command surcharging of the outflow control is handled in a more robust manner. This allows extrapolation of the H-Q-V data for cases in which only user-defined data is provided (i.e. no outflow control tools are used).
  • In the Rooftop storage option of the Pond command it is possible to re-define the available storage area instead of accepting the default of 75% of the building footprint. In Automatic mode a change of this type was not properly recorded in the output file. This has now been corrected.
  • In the Trench command an error occurred when attempting to estimate the required storage when the peak inflow was very small (< 0.01). This has been corrected. Also in the Trench command the plotting duration has been set to display the graphical results on a more convenient time base.
  • When running in Automatic mode use of the Tools/Comment comment command in Manual mode caused the text box to show extraneous text. This has been corrected.
  • When using the Hydrology/IUH Hydrograph command the tabular display of total volume sometimes showed the wrong units (e.g. cub.ft instead of acre-ft). This has been corrected.
  • When using the Show/Graph command to plot a hydrograph with a peak flow less than 1.0 the scale range was increased to the nearest single significant figure. This has been changed to set the maximum scale reading to 2 significant figures.
  • In the Storm command use of *.MRD files (Mass Rainfall Distribution) previously required that all *.MRD files were stored in the \MIDUSS\ folder. This has been changed to allow *.MRD files in any folder to be used and the full path to such files is written to the output file to allow access in Automatic mode.
  • In the Pond command the outflow controls may include a pipe with positive or negative slope. If pipes of large diameter and very flat positive slope were used an error occurred in some situations. This has been corrected.
  • In the Pipe command a false warning appeared if the discharge is very much smaller than the capacity of the smallest default pipe size used by MIDUSS. This has been corrected.
  • In Automatic mode it was sometimes necessary to click twice on the [Accept] command button in the Pipe and Channel commands. This has been corrected.
  • An error in the display of object coordinates in the Layout feature has been corrected. Previously, the displayed length of a channel object was shown incorrectly following a drag-and-drop operation.
2.01Rev329 May 17, 2004
  • When running in automatic mode, the Diversion command displays the correct description of the diverted file.
  • The list of default pipe diameters in the Pipe command has been increased and modified to match industry standards (metric and US customary units).
  • In the Layout drawing a Pond, Culvert or cascade icon was linked to the diverted node rather than to the transmitted hydrograph node. This was only a cosmetic error and has been corrected.
  • When the Layout drawing contains many new tributaries the initial icon (e.g. catchment or hydrograph) was sometimes located too low/high on the drawing requiring the user to increase the height of the drawing. This has been modified to simplify drawing of complex drainage networks.
  • When a new Catchment is added after a Confluence a warning message was incorrectly displayed. This has been corrected.
  • The ‘File/Repeat from Start’ command has been corrected to handle situations in which junction files (e.g. HYD….JNC) are created prior to the ‘Repeat from Start’. The Layout drawing now correctly handles networks containing ‘trailing’ tributaries (i.e. branches not yet connected to junction nodes).
  • If the Catchment command was used 2 or more times with a different storm depth, and the SCS option was used, the computed runoff coefficient was not re-computed to reflect the change in the total depth of precipitation. This has been corrected so that for a user defined Curve number CN any change of storm depth causes a change in the runoff coefficient.
2.01Rev321 April 14, 2004
  • Code The TRENCH design was modified to reduce the routing time-step in cases in which the lowest outflow invert is above the highest point in the trench.  In such cases both dV/dH and dQ/dH are zero which may give rise to numerically unstable conditions.
  • In automatic mode the display of available junction files during combine and confluence operations became corrupted.  This has been corrected.
2.01Rev319 April 6, 2004
  • Code was added to retain the Path to applications Notepad, Wordpad and Calc if this was edited by the user. Previously, the default for the Windows version was used. This was required in cases in which the Windows folder was changed to WinNT or vice-versa or when Windows 2000/XP was installed over Windows 9x.
  • The Hydrograph/Combine feature was modified to work correctly after use of the File/Repeat from Start command.
  • Code was added to the File/Load Session command to detect any junction files that may be required to continue the session but which are not in the current folder. Other changes were made to create auxiliary files (e.g. Design.log, Qpeaks.txt) in the same folder in which the binary file was located.
  • Several minor changes were made to improve the accuracy of the Layout feature.
  • A number of cosmetic changes were made to the Design Trench command forms.
  • A small fraction of users running MIDUSS under Windows 2000 & XP reported a problem in using the Automatic commands. This was discovered to be certain automatic updates to the operating system. As a result it proved necessary to completely rebuild MIDUSS with a more recent version of Visual Basic. The executable is significantly larger but execution is improved and the database problems have been removed.
  • The Design Cascade command was corrected to allow it to be used both before and after use of the Load Session command.
  • The Design Culvert command was modified to improve the accuracy of flow profile calculation when running under Outlet control.
  • Code was corrected in the Design Trench command that had caused the number of stages to be changed when running in Automatic mode.
2.00Rev207 Feb. 19, 2004
  • In the ‘Hydrology ‘ menu the item to re-set the area totals to zero has been corrected to display the new value in the menu text.
  • Code has been corrected in the ‘Files/Load/Hydrograph/Test Hyd.’ to properly display in the Peak flows summary table. With the addition of this item the menu item ‘Hydrograph/Move Outflow to Test’ is no longer necessary and has been deleted.
  • Code was corrected to handle the ‘Hydrograph/Undo’ command following use of the ‘Combine’ or ‘Confluence’ commands.
  • Code was corrected for the case in which the ‘Hydrograph/Start New Tributary’ command is followed immediately with the ‘Hydrograph/Undo’ command to avoid corruption of the Layout window.
  • In the Trench Design, an error in revising the Orifice parameters has been corrected.  A false error when editing the trench cross-section data (Ground elevation & Invert) has been removed.
  • The Design menu has been modified to show the last designed conduit (Pipe or Channel) against the Route command, and the Route command is now disabled after any of the other Design commands (e.g. Cascade, Culvert, Diversion, Pond and Trench)
  • In the Channel command the scale factors defining the drawing area (used to describe complex cross-sections) have been adjusted.
  • In the Trench command the program attempted to replot the trench profile whenever the ground elevation or trench invert was altered. This caused an error if the value of (Ground elev. – trench invert) was temporarily less than zero. This has been corrected.
  • The Help/About form includes Windows Server 2003 as a supported operating system
  • The Design/Culvert command has been corrected for the case that the user presses [Accept] without having used the [Route] button even when an inflow hydrograph is present. The output file for the Culvert command includes the Level-Discharge-Volume data only if the [Route] button has been pressed. Automatic processing of the Culvert command has been modified to suit.
  • For Windows 2000, XP and Server 2003 a first use of MIDUSS attempts to create a folder \MIDUSSData\ under the \My Documents\ folder for the current user. Code has been added to trap a condition in which the Windows default directory structure has been altered by accident or design.
  • The Roughness Height tool was updated to copy the computed Manning ‘n’ to the Culvert command as well as the Pipe or Channel commands.
  • Some cosmetic corrections made to the Design/Route command window.
  • In the Design/Trench command the plot duration is set to a reasonable value if inflow is defined either by a Catchment or IUH (Instantaneous Unit Hydrograph) command. Also, the Layout window now correctly plots a trench the inflow for which is defined by either an IUH command or by importing a hydrograph file.
  • If a Pipe or Channel design is followed immediately with another design option without using Design/Route or Hydrograph/Next Link the error is detected and a message gives the user a choice to either abandon the current Design option or delete the previous Pipe or Channel design


2.00Rev200 Feb. 8, 2004
New release of MIDUSS Version 2


Known Issues we are working on correcting

  • Layout:
    After designing a pond and then mistakenly used the Add Runoff command MIDUSS does not properly trap this error and this confuses the layout processing.  Work around: Do not use this command after routing a pond or if it exists in an output file, manually delete this command or SKIP over it during an automatic run.
  • Pond:
    If you have designed a pond and there is a MIDUSS message "Not enough storage and/or discharge ....try using pond again with a maximum water level of xx".  MIDUSS does not allow you to recover from this engineering design without cancelling the pond design.  Work around: Cancel the pond design and try an improved design until the MIDUSS warning is no longer displayed.

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v2.25 Rev468
March 6, 2009
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