Program Updates - Version 6.1

Following is a list of program changes and enhancements relative to Version 5.4 (December, 1998), as described in the User's Manual (Walker, 1999):

• The program has been translated from MSDOS Fortran to a Microsoft Windows application and recoded in Visual Basic 6.0.  It is been tested on the Windows 2000 & XP operating systems running Excel 2000 or 2002.  It may not run on computers with other Windows and/or Excel versions.
• Microsoft Excel is used to generate output tables & graphs.  Excel must be installed in the user's computer in order to run Version 6.x.
• The user interface (menu structure, input screens, output formats, help system ) has been changed to take advantage of Windows features.
• Program output can be directed to an Excel workbook, a text window, or Notepad (a text editor normally supplied with the Windows operating system).
• The input file format has been changed from binary to ASCII.  Version 6.x input files have a 'BTB' extension (e.g., KEYSTONE.BTB).  The 'Case Translate' procedure converts Version 5.x input files ('BIN' extension) into Version 6.x input files. 
• In Version 6.x, internal loads are attached directly to segments and edited along with other segment properties.  In Version 5.x, internal nutrient loads were specified using a tributary with a Type Code = 5.   The tributary coding system has been adjusted to reflect this change.  These changes are automatically applied when a Version 5.x input file is translated  to Version 6.x.
• Both global & segment calibration factors are applied to model predictions according to the calibration options settings. 
• If a tributary is specified as a non-point input (Type Code = 2), flows & concentrations are always estimated based upon user-specified export coefficients and drainage areas in each land use.  Direct inputs of flow or concentration are ignored. Therefore, drainage areas in each land use must be specified (Edit Tributaries), along with corresponding export coefficients ( Edit Export Coefficients) for tributaries classified as non-point inputs.  In Version 5.x, export coefficients were used in Type=2 tributaries only if land use areas were specified (otherwise, direct input flows & concentrations were used).  Inputs filestranslated from Version 5.x are adjusted to account for this change (The type code is changed from 2 to 1 if flows are directly specified but drainage areas are not specified for a given tributary).
• Values for mixed layer depth and non-algal turbidity must be entered directly by the user for each segment if Chlorophyll-a Models 1 or 2 are used. 
• Input values can be edited on individual screens ( Global Variables , Segments, Tributaries, Model Coefficients , etc.) or on an Excel worksheet .
• A new procedure ( Run Load Response ) evaluates the response of water quality in any segment to changes in phosphorus loads from any tributary.
• Edit procedures to add, insert, or delete segments or tributaries are provided.
• The numbering schemes previously used to identify segments, tributaries, type codes, & transport channels are now more or less transparent to the user.  These inputs are now specified by name, rather than number, on edit screens.
• Error analyses and ranking are performed for all output variables (vs. a subset in Version 5.x).
• Additional models have been added for phosphorus, chlorophyll-a, & transparency to support lake applications, including Canfield/Bachman (1981) P retention models for natural lakes & Carlson (1977) chlorophyll-a & secchi models.
• The maximum number of segments has been increased from 39 to 50.
• Additional sample cases have been added.
• The Help file   has been translated to HTML-help format with a table of contents and hyperlinks to related topics.
• The Help file has been augmented to include a discussion of the underlying theory, typical application sequence , a list of the equations associated with each model option, and detailed descriptions of output variables .
• Aside from items discussed above, the model structure and equations are identical to those contained in Version 5.x, as documented and discussed in the User's Manual ( Walker, 1999 ).