What is GIS?

by Caleb Mathias

Maps have been around for centuries: guiding expeditions out at sea, utilized for war tactics, marking political boundaries, and simply helping familiarize ourselves to new environments. GIS, an acronym for Geographic Information Systems, is a term that has become increasingly ubiquitous in recent years as the field of study grows in public prominence, but what does it mean exactly?

The roots of GIS are founded upon a rich history of cartography—the scientific art of map making. Cartographers in the United States were sent far and wide by the US Geological Survey in the nineteenth and twentieth centuries, armed with a plane table and telescopic alidade, to record the diverse beauty of this country in the form of topographic maps. Hiking mountains and traversing all imaginable terrain, the nuanced maps they produced are filled with details reflecting the regions we treasure and, in some instances, even serve as an archive of pre-metropolitan landscapes. The field of GIS can be thought of as a natural progression from the foundation these cartographers established, now incorporating knowledge from a wide swath of disciplines and bolstered by the rise of advanced computation.

I have been learning about and working with GIS for a couple years now, but my first encounters with the field inspired not intrigue but confusion. The insularity of language was an initial hurdle to my involvement and turned me away from actively pursuing its capabilities. Simply put, GIS consists of five components: the hardware used to compute data, the collected data itself, methods to help achieve desired outcomes, software for processing and visualizing information, and, most importantly, people. When I realized GIS was more a term to describe all the components that go into producing maps and data that help us understand the complexities of our world with the help of visual and spatial components, the importance of this field started to rear its head like a hydra of possibilities.

If you were to go online and pull up a news website right now, chances are you will see some information utilizing GIS technology, the most timely example being COVID-19 maps updated daily and obsessively to inform citizens which counties and states have the highest risk. Or perhaps you may come across an article about increased occurrence of algal blooms, a harmful effect of climate change. Satellite imagery can detect these algal blooms and help scientists make informed decisions on how to manage water resources being negatively impacted. Or perhaps you want to use GIS to turn a hike into a self-guided tour, revealing the landscape’s rich secrets hidden in plain sight.

Chocorua Lake Conservancy’s very own Rick Allmendinger, a structural geologist and Professor Emeritus at Cornell University, developed the Chocorua Map app to help make trails and details about the New Hampshire environment more accessible utilizing GIS technology. Now you can discover what bedrock lies beneath your hiking boots or the presence of bygone foundations in the Lake Basin. I spoke with Rick to hear his thoughts on this burgeoning field:

Caleb Mathias: How did you become involved with GIS?

Rick Allmendinger: Being a geologist means establishing the correct spatial relationships between geological features. A rock sample or measurement is meaningless without its spatial context.

Caleb Mathias: What compelled you to create the Chocorua Map app?

Rick Allmendinger: Frankly, I write all of my programs for my own use first and foremost and then, if they are useful, I’ll release them for free so the others can use them. I had been completely fascinated with the Chocorua LiDAR (Light Detection and Ranging, a way to generate detailed topographic maps using satellites and airborne sensors) data for some time because of the extraordinary detail it provided. When I used existing hiking apps, I found them frustrating because the built-in base maps are so crude compared to the LiDAR and of course none of them have built in DEMs (Digital Elevation Models) so you can measure things that you might actually want to know, like, how steep is this section of trail.

So, I wrote the Chocorua Map app so that I could hike the trails and see what the fascinating features on the LiDAR actually looked like in the field.

Caleb Mathias: What role do you see GIS playing in the future, at Lake Chocorua and/or around the world?

Rick Allmendinger: GIS is how we put the world into its proper spatial context. The most obvious example for most people are property boundaries. If we cannot establish those boundaries with certainty, then conflicts are bound to arise.

GIS will play a central role in the White Mountain Trail Collective project to address trail overuse on Chocorua. I would think, for example, that if one were rerouting trail sections, using the LiDAR dataset would be fundamental for locating the best alternative routings.

Caleb Mathias: Do you have any favorite aspects of the application?

Rick Allmendinger: As a geologist, I probably use the app in ways that are quite different than most people, for example to look at the ropey textured terrain on the lower parts of the Hammond trail (but above the obvious eskers), or how the mega glacial lineations seem to deviate around various topographic features.

I’d say for most people the thing that makes the app unique is the ability to plot topographic profiles of all of the trails on and around Chocorua. Thus the hiker can anticipate how steep their preferred trail will be and for how long (i.e., how hard it will be) and it is also good for trivia questions like: what is the steepest half mile of trail on Chocorua (answer: the upper part of the Brook Trail that is about 18° slope for about a half mile). A lot of people think that the Hammond Trail below Bald Mountain is pretty steep, but it is only 12°!

The other feature that few people know about is the ability to construct custom hikes which are made up of segments of individual trails. For example, last fall I did a hike that followed: Piper-Liberty-Hammond-Weetamoo-Piper, and with the custom hike I could tell just how far I had gone, how far to go, and where the steep parts of each trail are.

Ed. Would you like to learn more about the geology of the Chocorua Lake Basin? Rick Allmendinger will be leading two geology walks this summer, on June 24 and August 7.

About Caleb Mathias: “I recently moved to this area from Tennessee with an academic background in geology, now pursuing graduate school in environmental GIS. Upon moving to New Hampshire, Mount Chocorua and the Lake Basin were the first landmarks to capture my attention and help me connect to the state’s natural splendor.”

Banner image: LiDAR image of the Chocorua Lake Basin overlaid with geological descriptions. Image courtesy of Rick Allmendinger