Using Google Earth Layers to Understand Local Geomorphology
Using observations of the topography of their local county and prerequisite knowledge of geomorphology and geology, students develop hypotheses about surface water flow patterns and groundwater flooding patterns. Students must come into this exercise with some prerequisite skills/knowledge: glacial geomorphology of the Puget Lowland; using Google Earth; basic hydrology and hydrogeology. They use a case study of shallow groundwater flooding in Pierce County, Washington and imagery in Google Earth (via KMZ files) to develop their hypotheses. Hypotheses can be partially tested by viewing further imagery in Google Earth of actual surface hydrology.
Students finish by 1) reflecting on how local geomorphic features, and the hydrologic patterns caused by them, have impacted development in the area; 2) reflecting on how they have personally interacted with local geomorphic or hydrologic features; 3) developing strategies for collecting field data to establish actual hydrologic patterns and shallow ground water flooding patterns. Examples of strategies may include determining the pattern of basement flooding in residences, or distribution of problem public properties such as chronically flooded parks.
Through this exercise students develop a stronger sense of place with respect to how local geomorphology impacts their daily lives.
By drawing on their understanding of the recent geologic history of the Tacoma area, reading a case study, and working with different layers in Google Earth students will be able to:
1) describe the dominant role of glacial action in generating the local geomorphology and identify a few of the most common geomorphic features;
2) explain the influence of the geologic substrate on surface and groundwater flow;
3) distinguish between flooding caused by rising groundwater versus slow infiltration of surface water downward;
4) explain how topography effects surface and groundwater flow;
5) explain how the age of a stream effects its relationship with the landscape over which it flows;
6) cite examples of the effects of surface and groundwater flow on local development patterns, and how the urban landscape gets used by residents;
7) conceive of a field research plan to test ideas about how geologic features and materials control groundwater and surface water flooding.
Context for Use
This activity will work fine as a short stand-alone lab during a single class session. It would also work in an online class. Alternatively, it could be scaled up in various ways. Students could follow through with their field data collection strategies, making it a longer term project. There is some prerequisite knowledge needed, and that needs to be accounted for when scheduling the exercise.
The activity is probably best suited for an introductory earth science class or physical geography class. Maybe it could be expanded for an upper division hydrology class by including extra work like hydraulic conductivity studies of local soils and geologic materials.
The content of this exercise is very place-based, relevant to the Tacoma area specifically. Instructors wanting to adapt this exercise for their own areas would need to develop site-specific KMZ layers and site-specific questions.
Description and Teaching Materials
1) A complete written copy of the exercise is provided here. It includes a description of the necessary prerequisite knowledge, goals, and instructions. In addition, Also, I include a written copy with the answer key.
Geomorphologic controls on Tacoma area hydrology Complete exercise (Microsoft Word 2007 (.docx) 19kB Apr14 11)
KEY—Geomorphologic controls on Tacoma area hydrology KEY---Geomorphologic controls on Tacoma area hydrology (Microsoft Word 2007 (.docx) 21kB Jul27 11)
2) Shallow groundwater flooding case study
Ground-water Flooding in Glacial Terrain of Southern Puget Sound, USGS Fact Sheet Shallow Ground-water flooding (Acrobat (PDF) 953kB Jan28 11)
KMZ of Pierce County streams Pierce County streams KMZ (KMZ File 2.4MB Jan27 11)
KMZ of Pierce County water bodies Pierce County water bodies KMZ (KMZ File 985kB Jan27 11)
KMZ of Pierce County watershed boundaries Pierce County watershed boundaries KMZ (KMZ File 645kB Jan27 11)
Teaching Notes and Tips
The most important point is that students need to enter this exercise with the appropriate prerequisite skills and knowledge. They need to have been introduced to the glacial geomorphology of the Puget Lowland and the common geomorphic features and glacial sediments present here. They also need to be proficient, at an introductory level, with Google Earth. And they need to have an introductory level background in hydrology and groundwater, the kind one would receive in an introductory geology or physical geography class.
Students turn in for grading and comments:
1) answers to the questions in the exercise (see a full exercise description in "Teaching Materials section");
2) two annotated screen captures, showing predicted stream locations and watershed boundaries;
3) four KMZ Place mark files identifying features associated with meandering streams.
References and Resources
USGS Fact Sheet 111-00. September 2000. Groundwater Flooding in Glacial Terrain in Southern Puget Sound, Washington.
KMZ data converted from the following sources:
1) Digital Elevation Models (Gig Harbor, Steilacoom, North Tacoma, South Tacoma quadrangles), 1:24,000. 2000. US Geological Survey.
2) Surface Geology, 1:100,000. 2010. Washington State Department of Natural Resources, GIS Data Center. http://fortress.wa.gov/dnr/app1/dataweb/dmmatrix.html
3) Hydrography (by County), 1:24,000. 2010. Washington State Department of Natural Resources, GIS Data Center. http://fortress.wa.gov/dnr/app1/dataweb/dmmatrix.html
4) Watersheds, 1:100,000. 2000. Washington State, Pierce County GIS Department.
5) Hydro_Surface_Boundaries, 1:100,000. 2010. Washington State, Pierce County GIS Department.