Exercise 2: Visualizing contamination in an aquifer

Complexity: Beginner Data Requirement: Installed with software Data Path: See Copying the tutorial data Goal: Use ArcScene to assess the impact of a groundwater contaminate in an aquifer

Imagine that you work for a water district. The district is aware of some areas where volatile organic compounds (VOCs) have leaked over the years. Scientists from your department have mapped some plumes of VOCs in the aquifer, and you want to create a 3D scene to help officials and the public visualize the extent of the problem.

Some of the data has already been assembled in the Groundwater ArcScene document. You will modify the scene to better communicate the problem.

VOC data was supplied courtesy of the San Gabriel Basin Water Quality Authority.

Opening the Groundwater scene document

This scene document contains a TIN that shows the shape of the contaminant plume, a raster that shows the concentration of the contaminant, and two shapefiles that show the locations of parcels and wells. You will drape the concentration raster over the plume TIN, extrude the building features and change their color, and extrude the well features so that the wells most endangered by the contamination may be more easily recognized.

Steps:

1. Start ArcScene by clicking Start > All Programs > ArcGIS > ArcScene 10.

2. On the ArcScene - Getting Started dialog box, click Existing Scenes --> Browse for more.
The Open dialog box appears.
3. Navigate to the Exercise2 folder.
4. Click the Groundwater ArcScene document and click Open.

The Groundwater scene opens. You can see that four layers are already added to the table of contents.

Showing the volume and intensity of contamination

You’ll drape the raster of VOC concentration over the TIN of the contaminant plume surface to show the volume and intensity of contamination in the aquifer.

Steps:

1. Right-click congrd in the table of contents and click Properties.

2. Click the Base Heights tab.
3. Click Floating on a custom surface and make sure the plume TIN is selected as the elevation surface to provide height values.

Now you will change the symbology of the raster to show the intensity of the contamination.
4. Click the Symbology tab.
5. Click the Color Ramp drop-down arrow and click a red color ramp for the raster.

6. Click OK.
7. Uncheck plume in the table of contents.

Now it is possible to see the shape of the plume and its intensity in 3D.

Showing the relationship of the plume to wells

You can see that some of the wells are within the area of the plume. However, it is difficult to see which wells are most seriously affected because the contamination is more widespread but less concentrated at greater depths.

You will extrude the well features based on their depth attribute in order to see which wells intersect the plume.

Steps:

1. Right-click wells and click Properties.

2. Click the Extrusion tab.
3. Check to enable Extrude features in layer and click the Calculate Extrusion Expression button.

You will display the well points as vertical lines equal to the depth of the well. This information is stored in the WELL_DPTH field.
4. Click WELL_DPTH.
5. Click OK.

6. Click the drop-down arrow to apply the extrusion expression by adding it to each feature’s base height. The well depths are expressed as negative values, so they will be extruded downward.

7. Click OK.

You can see the places where the wells intersect, or are close to, the plume. Now you will modify the scene to show the priority of various facilities that have been targeted for cleanup.

Showing the facilities with a high cleanup priority

Analysts in your department have ranked the facilities according to the urgency of a cleanup at each location. You’ll extrude the facilities into 3D columns and color code them to emphasize those with a higher priority for cleanup.

Steps:

1. Right-click facility and click Properties.

2. Click the Extrusion tab.
3. Check Extrude features in layer and click the Calculate Extrusion Expression button.

4. Click PRIORITY1.
5. Type *100.
6. Click OK.

The expression you created appears in the Extrusion value or expression box.

7. Click the Symbology tab.
8. Click Quantities.
9. Click the Value drop-down list and click PRIORITY1.

10. Click OK to close the Layer Properties dialog box and apply the extrusion and symbology settings.
The facilities are now extruded in proportion to their priority score. The scene now shows the shape and intensity of the contamination, the wells in relationship to the plume, and the facilities that need to be cleaned up in order to prevent further pollution of the groundwater.
Now you’ll save your changes to the scene.
11. Click the Save button.