Field Methods: Navigation with GPS

Navigation with a GPS device using a UTM Coordinate System

Introduction and Study Area

This exercise builds off of the previous exercise involving navigating using a map and compass. I did not take place in the act of navigating through the study area, the Priory, because I actually taught the class the orienteering methods necessary to complete the short navigation course. The orienteering exercise was a brief introduction to the methods necessary to navigate using more primitive methods, such as a map and compass, versus the now normal methods of using GPS devices such as a Garmin eTrex, Trimble Juno3 series handheld unit, or a variety of other handheld GPS units available on the market, today.

This more recent exercise builds off of the orienteering exercise, however it allows us to utilize the handheld GPS systems that are generously available to us for use through the University of Wisconsin-Eau Claire Department of Geography and Anthropology. My group, consisting of Nicholas Bartelt, Les Warren, and myself, used a Trimble Juno 3 series to complete the exercise. The objective of this exercise was to develop a course for the next section of Geography 336: Field Methods for the fall semester of 2015. As our initial orienteering exercise took place on the UW-Eau Claire property known as the Priory, this exercise did too. We were to conduct a five point course for the incoming GEOG336 students to navigate.

As stated before, this exercise took place at the Priory, a 120 acre property owned by the University of Wisconsin-Eau Claire. The Priory is within Eau Claire County, in the town of Washington, approximately three miles south of the University of Wisconsin-Eau Claire campus. The north edge of the Priory is bounded by the eastbound lane of Interstate 94, while the south edge is bounded by Priory Road (Figure 1). This area is referred to as being in bedrock uplands, so relief is very great at the Priory. Fluvial processes and anthropogenic tendencies have created a number of very steep, deep, and long gullies that transect the property. A resistant bedrock ridge interpreted as Late Cambrian Mt. Simon Formation bedrock exists, upon which the main building of the Priory has been built upon.

Figure 1. Map showing the location and layout of the Priory.

Methods

The completion of this exercise was carried out without issue. We started by plotting points on a previously developed navigation map of the Priory that utilized a Universal Transverse Mercator (UTM) coordinate grid (Figure 2).

Figure 2. Map developed for the orienteering exercise that was utilized for the GPS navigation exercise. The map was developed by Les Warren. 

As stated before, the GPS unit used for this exercise was the Trimble Juno 3 series handheld unit. The Juno 3 has been used for numerous exercises prior to this and we have become very familiar with how to properly record field data with it (Figure 3).

Figure 3. This image shows the Trimble Juno 3 Series. This unit was used to record the locations of the points we picked to serve as one of the new courses for the next Field Methods class.

In the field, large trees were selected at the locations that we had determined we wanted points at. The trees were marked with pink survey tape and numbered based on the group number and what number the point was in the track (ex. 2-1, 2-2, 2-3, 2-4, 2-5).

Results
Five trees were selected and the course was spread out over a sizable terrain. Figure 4 shows a table with the XY coordinates for the points listed. Figures 5-9 show the trees with the survey tape on them that were chosen in the field. Two maps were produced to show the elevation difference and the slope of the course we laid out (Figure 10-11).

Figure 4. Table that shows each point, what the point was placed on, and the XYZ coordinates for each point. XY are in reference to UTM coordinates and Z is listed in meters above mean sea level.

Figure 5. Point 2-1.

Figure 6. Point 2-2.

Figure 7. Point 2-3.

Figure 8. Point 2-4.

Figure 9. Point 2-5.

Figure 10. Data showing elevation at the Priory. This course experiences a difference of elevation of 42.1 meters. 

Figure 11. Slope steepness by percent at the Priory. This course we chose traverses some steep slopes and through one large gully.

Discussion and Conclusion

There are a few potential sources of issue for the students who will be running this course in the fall. One issue, which I observed when watching the two years worth of students conduct the orienteering exercise, was that there seems to be an aversion to going down into gullies. In order to properly conduct an accurate exercise, using proper methods of orienteering, one must try to maintain straight lines and count their paces. If the students are skirting around the edges of the gullies then their results will hardly be accurate. Another issue I noticed was groups not using their numbers to the best of their abilities. If a group had two or three people then proper resource allocation needs to be practiced. One person should act as a runner, one as an anchor, and one as the navigator. This will ensure that if mistakes are made then the groups can return and reevaluate. Most groups never seemed to get over this. Misuse of resources and an aversion to gullies seem to be the largest downfalls groups encounter. If they are able to overcome these issues then they complete this exercise with relative ease.

This was an easier exercise that allowed us to use our experiences and devise a course for future GEOG 336: Field Methods students. This exercise did not require an immense amount of critical thinking, though it did help to reinforce some of the skills we had learned before, like how to read maps and the land around us and how to properly utilize and extract data from the Juno 3 units.