Discovering Geographical Information Systems: Quantum GIS

I had gotten frustrated with creating site maps in AutoCad 12 LT, and yesterday’s field work was postponed because of rain. Additionally, Quantum GIS software is free. This turned out to be a great combination.

Not to bash AutoCAD 12 LT (for non-technical readers – AutoCAD LT is the “Lite” version of a common engineering drafting software program)- it’s been great for creating site maps for industrial clients who can send me their base plans already in AutoCAD format. I add some new layers for their hazardous waste locations and protocols, drop it into my company’s standard frame, and voila. However, I was going back to my company’s decade-old protocol for mapping monitoring wells in AutoCAD and found it cumbersome. In order to make an accurate map I had to take a screenshot of Google Earth, save it, attach it as an external reference file, adjust the raster DPI so it didn’t look like an 8-bit video game, and then set the layer properties so it wouldn’t accidentally be moved while I added feature points. With that done, I had to go back to Google Earth and transfer a scale – and good luck if I had zoomed the map to fit the site boundaries while in AutoCAD. Once the well locations and site outlines were traced, I would delete the base map. I figured that there had to be a simpler way to do this.

I got the decisive nudge towards exploring Quantum GIS from a geologist friend whose specialty is managing complicated Oracle/ESRI ArcGIS systems.   We were having our usual nerdy kind of conversation over dinner on Friday (planetary plausibility of Star Trek, using radar to map the subsurface of Mars, oil pipelines, etc) when I brought up my mapping conundrum. I had been using the free version of Google Earth Pro but it lacked some of the features I wanted, and he suggested QGIS as the next step up.

Quantum GIS (QGIS) can be downloaded here.

I will freely admit that even though I had done some basic cartography in ArcGIS a few years back, I had little idea what to do next. QGIS has a graphical interface comparable to AutoCAD LT, actually – helpful enough but not completely intuitive. Luckily, there’s an instruction video for pretty much everything on YouTube.

Klas Karlsson created a clear, concise, and useful walk-through of a basic project – you can find it here.

Next I wanted to find a general overview of what the software could do – which“A Gentle Introduction to GIS” by T. Sutton, O. Dassau, and M. Sutton of the Department of Land Affairs of South Africa does nicely. This free text serves as an introduction to geographical information systems in general, but focuses on QGIS. It does a good job of making the software less intimidating, answered my questions about the cartography projections I had to choose between,  and gave me a basic view of the analytical capabilities I can learn in the future.

So, to compare map outcomes (…drumroll…):

Estimated water table surface map made with AutoCAD 12 LT:

Versus a map of the same site made with QGIS (client data blurred out):

This landfill in West Tennessee hasn’t had any contamination in the years my employer has been sampling here – good for the planet and keeping my job simple!

For now I drafted the water surface elevation contours and flow direction by hand and then digitized them, as my company has done in the past. However, I know that somewhere in the jungle of optional plugins there’s a way to make QGIS create groundwater contours based on my data points. That’s going to take more than an afternoon’s study to master though, and I look forward to getting to that point!

UPDATE 6/1/2017: the “contour” plugin is really easy to use. Luckily my hand-drafted curves weren’t too terribly off from the calculated curves. The figure below shows the calculated curves in brown.

Advantages to AutoCAD LT:

• Ability to draw splines/curved lines, easily rotate shapes and text
• Faster rendering time between zoom frames
• Option for typed commands instead of click-and-select
• Format is widely used across engineering and environmental consulting fields

Advantages to Quantum GIS:

• Base maps are so easy to insert, delete, and switch out!
• Ease of entering attribute data, and ability to make any variable of that attribute data a visible tag on a feature location
• Can enter well locations based on the coordinates measured in the field
• Easy to measure distances
• Instant scale
• Instant and easily modified legend
• Spatial analysis, once I figure out how to use it
• FREE

After this intro I’m hooked on the possibilities of QGIS. I’m seriously tempted to digitize my hand-sketched field camp maps and start using it for my Phase I Environmental Site Assessment maps…

I definitely have enough left to learn to fill many a rainy day to come.

How do you use GIS in your work and research? I’d love to hear about it in the comments.

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