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Customer Spotlight: Willem Havermans Uses Voxler & Surfer To Visualize Groundwater Contamination

Golden Software customers possess a broad assortment of backgrounds, from earth science and engineering to education and politics. This vast background results in a variety of uses for Golden Software’s products. Each customer uses our software in their own unique way, and we are pleased to share these stories. This blog features Willem Havermans, a senior engineering consultant for MWH Global, who uses a combination of Voxler and Surfer's mapping software to visualize groundwater contamination levels and generate conceptual remediation models for their areas of interest.

Willem Havermans has been a faithful user of Golden Software applications dating back to early 2000. He has purchased multiple versions of Surfer's mapping software. He also uses Voxler's 3D data visualization capabilities on a daily basis and has held a Strater license for the past few versions. Havermans, working with MWH Global, uses a combination of Voxler and Surfer to perform 3D data processing of surface and subsurface soil contamination and surface creation. He uses Goolden Software's mapping software to create a strong basis for generating conceptual models of groundwater contamination and in planning of remedial designs.

Why does Havermans take a 3D approach to modeling groundwater contamination, as opposed a traditional top-down, slice-modeling approach? Havermans feels that with the traditional modeling approach, relationships between a series of 2D slices are typically difficult to interpret, can introduce human-caused error, and quite often volumetric calculations of containments levels are estimated. Making use of models that employ 3D interpolation of adjacent down-hole data samples offers the possibility of displaying the presence of contamination in a 3D view. For this purpose, Havermans' 3D interpolations are made using Voxler.

Voxler Groundwater Contamination
A top-down view of a groundwater contamination model that was generated by Willem Havermans
in Voxler. The different groundwater contamination levels in the city of The Hague, Netherlands
are rendered by using multiple Isosurface modules and a WellRender module.

Havermans used Voxler and Surfer to develop a 3D model of groundwater contamination in the city of The Hague, Netherlands. The model was based on an array of monitoring well data; where concentration levels of contaminants were developed for the area of interest through 3D interpretations that were calculated using Voxler’s Gridder. Once the groundwater contamination data was gridded, Isosurfaces for the different contamination thresholds were generated for the area. Voxler is used to calculate the size of the soil volume for each of the contaminant threshold levels, allowing the stakeholders to get a good assessment of the volume of soil that requires mediation work. The pathways and direction of the contamination plumes are easily visualized spatially because Voxler supports various types of GIS raster and vector data.

Voxler Groundwater Contamination - Cross Section
A perspective cross sectional view of the contamination thresholds, generated in Voxler, that are
rendered by various Isosurface modules that have been clipped to pinpoint the most contaminated
locations. This model aids the remediation team in figuring out where to focus their remediation efforts.

Havermans is particularly fond of Voxler because once a model is set-up; it can be easily updated within a few mouse clicks when new data becomes available from the monitoring wells. Contamination threshold Contours and Isosurfaces and be regenerated by updating the gridder. This allows Havermans to manage the groundwater contaminations over time, where he can see differences in concentrations and recalculate soil contaminations. He indicates that managing groundwater contamination data over time is extremely beneficial in directing ongoing remediation efforts. Havermans also exports the gridded contamination data from Voxler so that is can be easily combined with groundwater modeling software like MODFLOW to predict contamination behavior and remediation progress over time.

Third Image
A front view of the various contamination threshold Isosurfaces
in conjunction with a series of monitoring wells.

 

Download the PDF version of this article.

 

Comments 1

Guest - groundwater modeling on Tuesday, 22 November 2016 23:44

Great project on key global issue. The key risk for sustainability is recharge rate vs extraction rate. Many aquifers are ancient and not being replenished and as such it is simply groundwater mining where the true cost of the water is not paid by the entity extracting.

Great project on key global issue. The key risk for sustainability is recharge rate vs extraction rate. Many aquifers are ancient and not being replenished and as such it is simply groundwater mining where the true cost of the water is not paid by the entity extracting.
Guest
Tuesday, 17 January 2017

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05 January 2016
Surfer

There many methods for displaying contour lines in visualization and GIS software programs. In most cases, representing terrain data with standard contours or hillshading techniques are sufficient. In other cases, you may want a more artistic technique to help emphasize specific features in the data or to make the map more pleasing to the eye. One of these techniques is using the Tanaka method for creating illuminated contours. I recently read an article about how to create illuminated contours in ArcGIS and couldn’t resist trying to replicate the results in Surfer's mapping software.

The Tanaka method applies a northwest light source to a contour map. The contour lines then change in color and width based on their relationship to the light source. Contour lines facing the light source are drawn in white while those in the shadow are drawn in black. The contour lines facing the light source (or facing away from it) are thicker, and the contour lines in the orthogonal direction are thinner. A more detailed explanation of the method can be found online at: http://www.mbmg.mtech.edu/pdf/gis_illum.pdf

While Surfer's mapping data software cannot change the width of the contour lines and create a contour map as in the true Tanaka method, you can alter the colors based on the light source and create a very similar effect.

Tanaka style illuminated contours vs standard hillshading and contoursThe same map is displayed using various techniques. A map with a Tanaka-style effect is shown at the top, a map showing standard hillshading is shown in the lower left, and a map showing standard filled color contours is displayed in the lower right. All maps are created in Surfer 13.

To create a map with a Tanaka-style effect in Surfer, you start with a grid file. If you do not have a grid file (a.k.a., a raster), you can either:

  1. Download it from an online source, such as the USGS. In this example, we will use an example file, NEDGrid_CO.grd.
  2. Generate one in a different software package.
  3. Use the Grid | Data command in Surfer to create a grid file from a set of XYZ data points.

 

In addition, the grid file should have a relatively high resolution. I find that a grid file with around 2000 grid nodes minimum works well. If you do not have sufficiently high grid resolution, then the “contour lines” do not look as defined in the resulting map. If you have a grid file, but it is a low-resolution grid file, then you can increase the resolution by following the steps below. Click here to download the grid NEDGrid_CO.grd which we will use in this example.

  1. Click Grid | Spline Smooth.
  2. Select the low-resolution grid file, such as NEDGrid_CO.grd, and click Open.
  3. In the Spline Smooth dialog, under Number Nodes to Insert, increase the number so that the Final Grid Size shows around 2000 nodes in X and Y.  For this grid, I will change the Between Rows and Between Cols values both to 1 so the final grid will be 2459 x 2461.
  4. Click the Change Filename button to the right of Output Grid File to change the file name and/or location of the modified grid file.
  5. Click OK.

 

Once you have a high resolution grid, you can follow the steps below to create the Tanaka-style contour map:

  1. Click Grid | Math.
  2. In the Grid Math dialog, click the Add Grids button, select the high resolution grid file and click Open.
  3. Enter the following function to quantize the Z elevations: floor(A/100) * 100. In this function, 100 will be the “contour interval” in the resulting map. You can replace 100 in this function with any value you wish.
  4. Click the Change Filename button to the right of Output Grid File to change the file name and/or location of the modified grid file.
  5. Click OK.
  6. Click Map | New | Image Map, select the grid file created above and click Open.
  7. To fine tune the map, select the Image layer in the Property Manager, and in the Object Manager:
    1. Change the Colors to any colormap you wish. For example, click the button showing the Terrain colors and select Rainbow6.
    2. Make sure Interpolate pixels is checked.
    3. Enable hill shading should also be checked.
    4. Set the Horizontal light angle to 135°. This will place the light source in the northwest. For Surfer’s calculations, the 0° is directly to the right (“east” on a compass) and rotates counter-clockwise. So 315° on a compass azimuth (northwest) is actually 135° for Surfer.
    5. The Vertical light angle can changed to another value, such as 30. Increase this value if you wish to brighten the display, or decrease it to darken the display.
    6. Decrease the Z scale factor by about half the default value. You may need to experiment to find just the right value you want for your data.
    7. Increase the Ambient light intensity to 0.4. Again, you may want to try different values to find the right value for your data. If you use a larger vertical light angle (e.g. 35°), then you might want to try a slightly smaller ambient light intensity, such as 0.30.

Illuminated contours using Tanaka method

Create stunning illuminated “contours” in Surfer with the modified grid file using an image map with hillshading.

Although the map created in Surfer is not an illuminated contour map using the true Tanaka method (as the contour lines do not change thickness depending on their orientation to the light source), it is still a very beautiful alternative to displaying contours with standard hillshading.

References:

  1. http://www.mbmg.mtech.edu/pdf/gis_illum.pdf
  2. http://wiki.gis.com/wiki/index.php/Tanaka_contours
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30 December 2015
Surfer

Golden Software customers possess a broad assortment of backgrounds from earth sciences and engineering to education and politics. This vast background results in a variety of uses for Golden Software’s products. Each customer uses the software in a unique way, and we are pleased to share these stories. This blog features Dr. John Hall of the Geological Survey of Israel and his use of Surfer.

Dr. Hall is a marine geophysicist and doctoral graduate from Columbia University’s Lamont-Doherty Geological (now Earth) Observatory. Upon the completion of his doctorate, he worked for the Geological Survey of Israel until his retirement at the end of 2005. His research includes global tectonics, offshore geophysical surveys, and compilations of detailed gridded topography for Israel and neighboring areas. Although Dr. Hall is retired, he continues to utilize Golden Software’s own contouring, gridding, and 3D surface mapping program, Surfer.

“I have used Surfer since the time that it worked on piddling little grids with maybe 100 by 100 nodes and a thousand data points,” recalls Dr. Hall. His first copy of Surfer was a DOS version which ran on IBM’s Personal Computer Advanced-Technology (PC-AT). During this time, Dr. Hall used an innovative technique on the first PC-AT to generate grids. This technique generated the 25 meter grid of Israel by coloring in the areas between 10 meter contours on the 1:50,000 topographical sheets as he was not permitted to digitize the contours.

Surfer Grid Map - Israel
This image is the result of 12,000 hours of heads-up digitizing
on PC-ATs between 1987 and 1992 as viewed in Surfer.

Surfer has come a long way since the DOS version and is now used by Dr. Hall to create Digital Terrain Models (DTMs) of the Mediterranean Sea, the Black Sea, the Red Sea and the Caspian Sea. To create these DTMs, hundreds of thousands of digitized soundings are compiled and then gridded using Surfer’s kriging method. As is the case with most digitized soundings, errors, also known as artifacts, are prevalent; therefore Surfer is used to separate the artifacts from the DTMs for analysis. Combining the tools provided by Surfer and other mapping programs, Dr. Hall can generate impressive models.

Surfer Digital Terrain Model - Kriging Method
In 2010, Dr. Hall spent 44 days on the icebreaker, Healy, mapping
50,000 sq. km up to the North Pole to investigate new bathymetric features.
 

Dr. Hall’s recent projects are quite fascinating. Just last week, Dr. Hall kriged 46,000 digitized soundings and 10 meter contours for the Gulf of Suez to generate 50 meter UTM grids. The grids will be used by a professor at the University of California, Santa Cruz to create seiche animations to potentially illustrate how the Israelites crossed the Red Sea ~3,300 years ago. Additionally, Dr. Hall contributed to the General Bathymetric Chart of the Oceans (GEBCO) Cook Book for making grids of the world’s oceans and his chapter detailed his use of Surfer and the other software packages. He states Surfer “is the program of choice for interpolation of grids.”

We are pleased Dr. Hall has integrated Surfer into his workflow, and it is exciting to see his application of Surfer’s tools.

For additional information, visit the below links:

If you would like to be featured in a future Customer Spotlight, contact us.

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