Getting Started with GCLAS

Starting the program on a PC-Windows machine

Installation of GCLAS on a PC-Windows machine will add "USGS" to the list of programs that you run from the Start menu. To start GCLAS

• Go to the Start menu and select Programs.
• Drag down to USGS; the choice of GCLAS should pop up to the right.
• Drag over to GCLAS; when the next menu pops up to the right, drag over to GCLAS.

A DOS window will open briefly as GCLAS starts up. The GCLAS interface will appear shortly after that. You will probably want to maximize the GCLAS window to fit the whole monitor screen for the best view of all the GCLAS parts. Once you import some data, you can begin to see how GCLAS really looks and works.

Note: If the interface has a coarse or fuzzy look to it, check the screen resolution (also called "desktop area" or "screen area") to ensure that it is set to at least 1024 by 768 pixels. GCLAS requires a resolution of at least 1024 by 768 pixels for its display. (See installation instructions and/or your system administrator if there is a problem.)

Starting the program on a UNIX machine

With a standard installation of GCLAS on a UNIX machine, you should be able to start the program by typing the command gclas.

Importing data for analysis

Data can be imported into GCLAS from any local or networked file system. For purposes of getting started, however, a practice data set comes as part of the GCLAS installation. To import practice data:

1. From the File menu, select Import (or use the keyboard shortcut shift-i). This will open a file browser window.
   
   

2. Navigate to the data subdirectory of the GCLAS installation. In most PC-Windows installations, this will be on a local hard drive (probably C:\) in Program Files\USGS\gclas\data. With a standard UNIX installation, the practice data set can be found in the directory /usr/opt/wrdapp/gclas.

3. After you have located the data subdirectory, select the card file big.darby.sed.98 (a sediment-concentration file) and left click on the Import button to load the file into GCLAS.

4. Repeat the above process and select and load a streamflow unit-values file (big.darby.bcard.u.98; the concentration file and streamflow unit-values file must be from the same water year). Note: it is also possible to load daily values of streamflow in the daily-values card-image format.

5. Locate the folder and file display tree in the left-hand panel at the top GCLAS window. Expand the tree by double left clicking on the folder icon that has a station number as its label or by single left clicking on the toggle icon to the left of the folder. You will see nodes (file names) for any sediment and streamflow data that have been loaded.
   
   

6. Now left click on the file folder icon associated with the concentration file. The name of the concentration node should be highlighted.
   
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7. Click the right mouse button and choose the option to create a GCLAS year.
   
   

8. A window will appear, and the dialog box at the bottom of this window tells you how to proceed. Follow the instructions in the lower portion of the window to create the GCLAS year.
   
   

9. Creating the GCLAS year involves several steps, including (a) choosing a water year, concentration parameter, and load units, (b) optionally choosing a daily streamflow dataset, and (c) choosing a unit streamflow data set and parameter. After you've identified all necessary data sets and parameters, left click the Finish button (on the last menu) and GCLAS will display the data. (This could take a few seconds depending on the speed of your computer.)

You are now ready to explore more features of GCLAS!