EVS Chemistry File Creation in ArcView

LOAD A PROJECT:

The simplest way to start is to launch ArcView (version 3.1 or greater), at which point you will be prompted to create a new project by one of three choices. Choose the third choice (open an existing project), and browse to select CTECH\EVSforArcView\test_project_all.apr.

After this, you should see the following screen (note, View1 must be selected (active) to get the EVS pull down menu option.)

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CREATING A CHEMISTRY FILE:

The following section will show you how to build an EVS chemistry file (.csv) with ArcView.

To see the format for a CSV file click here: $image\shortcut.jpg$ Chemistry File Format

Now that the extension is loaded and the C Tech executable is properly specified, click on the EVS pull down menu to reveal:

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After selecting the file type (CSV):

Choose Select Tables to get the following:

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If the data you are using to create the CSV file is already completely contained in the shapefile (point theme) itself, and not in a related table, skip the step of linking fields below in blue...

Choose the following settings and hit OK (note, you must choose the Input Table before you can set the field to field links (relationships):

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Next: from the pull down menu choose "Create CSV File":

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At this point, you have two ways of specifying a chemistry file. You can load an existing file that will be used when you launch an application (in which case you could have skipped the "Select Tables" step), or you can specify the fields of your database to be used to create a chemistry file as below:

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In this example our Boring_ID is "Bore", the Surface Elevation is Top, Z Coords are Z and they represent true elevations (as opposed to depths below ground surface).

Note that in this example, only one field represents chemistry data, but the extension allows you to specify multiple fields for multiple chemicals or timesteps. Multiple selection is done with Shift Left Mouse Button (vs. the windows standard of CTRL).

There are two other very important fields in this window that should be carefully considered. They are the Pre Clip Min and Post Clip Min. These fields control the clipping parameters for pre and post processing in all of the EVS modules that use read chemistry (.csv) files. The affected modules are Krig_3D, Krig_Z, Krig_Fence, Map_Spheres, and Stat_CSV_GEO.

The three kriging modules use the Pre Clip Min values as the value to assign to non-detects or any value less than the clipping value. C Tech recommends that:

Pre Clip Min value should be set to a fraction of the detection limit for the selected analyte (chemicals or parameters).

When using "Log processing" the fraction should normally be one-tenth, but may be as high as one-half of the detection limit.

If all of the analytes for a site do not have the same detection limit it is best to krige them separately, using appropriate (fraction of detection limit) clipping values for each.

If all of the samples for any analyte do not have the same detection limit it is best to assign numeric values to your non-detects (fraction of detection limit) values for each non-detect value.

If you have already assigned numeric values to your non-detects be sure to set the Pre Clip Min value less than your lowest assigned value to prevent modifying your assigned values.

All five modules use the Post Clip Min values as the value to assign the final minimum values used in the output field (visualization). C Tech recommends that:

Post Clip Min value should be set to the actual (nominal) detection limit for the analyte. By doing this, you avoid having a model where any values are less than the detection limit. A lower value would not be defensible since your measurement techniques would be unable to verify the lower value.

If all of the analytes for a site do not have the same detection limit it is best to krige them separately, using appropriate detection limit clipping values for each. If you wish to have multiple analytes in the same field, they can be combined later using the combine_comp module. [This note only applies to the kriging modules.]

When you hit OK it will give you a file browser and allow you to name and specify the folder for your chemistry file: Accept or change the file name and location and hit OK.

Note: the default naming is evs#.csv where # will start at "1" and count up as you write new files to the same folder.

$image\csv_file.jpg$

If you are a licensed user, you can jump directly to Launch Applications or review the next topic which covers Loading Existing EVS Geology or Chemistry Files.