Human geomorphology and an introduction to GIS

Laura Triplett
Gustavus Adolphus College
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This page first made public: May 2, 2008


In this lab activity, students use a few basic GIS manuevers to quantify the hydrologic impact of building the Hoover Dam on the Colorado River. The main strength of the activity is that students learn how to take data that is freely available online to quantitatively answer an interesting geomorphic question.

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I use this in an upper-level geomorphology course that is required for all geology and environmental studies majors.

Skills and concepts that students must have mastered

They should know some basic fluvial concepts in order to appreciate the magnitude of changes in hydrology and sediment transport introduced by this one dam on the Colorado.

How the activity is situated in the course

It is a stand-alone lab exercise that I use about mid-semester.


Content/concepts goals for this activity

1) Calculating water lost due to evapotranspiration and calculating sediment trapped in reservoir
2) Learning basic tools of GIS

Higher order thinking skills goals for this activity

1) Comparing magnitude of human impacts to natural events
2) Evaluating strengths and weaknesses of GIS tools

Other skills goals for this activity

Description of the activity/assignment

This lab gives students a bare-bones introduction to one GIS software package, ArcMap. I hope that students will get comfortable with how GIS programs layer data, and that they will begin to appreciate the power of GIS for solving a wide variety of problems. Students access freely available shape files, and make a map of Lake Mead, the largest human-made reservoir in the United States. (It formed behind the Hoover Dam when that was constructed on the Colorado River in the 1930s.) Then, they compare the mass of water lost to evaporation from the surface of Lake Mead to the evaporation that was occurring from the surface of the pre-dam river. Finally, they make a map of some other location affected by human activities. This activity could easily be expanded to have students calculate the amount of sediment that has been trapped behind Lake Mead, because sediment depths are also available online.
Designed for a geomorphology course
Uses online and/or real-time data

Determining whether students have met the goals

At the end of the lab I ask students to make a map of another place that is impacted by human activity and that has DEM data. I find that they enjoy 'surfing' around looking for data in their favorite vacation spots, and by repeating the map-making steps they are more likely to understand the process. The last question of the exercise asks them to analyze the work that they've done by deciding whether they could repeat the tasks by hand (without GIS).

More information about assessment tools and techniques.

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Supporting references/URLs

Lake Mead shape files are here:
Or, you can find them by searching for the USGS Open File Report 03-320.
I have attached 4 shape files, but did not attach the base map shape file (NED_21978736) because that is freely available at and was too large (~38MB).