Priory Navigation Exercise

For this assignment, the class headed over to The Priory in Eau Claire, Wisconsin and prepared to navigate the wooded area to find the location of a total of five trees. Once there, students were split into groups of three and given the UTM coordinates of the five tree locations. Additionally, each group was provided a can of spray paint and ribbon to mark their trees once found, and a tracker so that Professor Hupy would be able to review the group's course later on, and confirm that the trees in which they selected were marked correctly. Using a previously made map and handheld GPS device, the students began their descent into the forest, and began locating and making their designated trees. Figure 1 below shows a student marking a located tree with ribbon.

Figure 1: Marking a tree with ribbon

The terrain in the wooded area had extreme ranges in elevation at different various points. In some instances, it was more beneficial to walk around the ridges rather than attempting to cut through them, especially with the ground being wet and slippery from rain, which continued throughout the navigation excursion. The combined cloud and tree coverage made the GPS units lag quite a bit when travelling from site to site. Also, GPS units from the phone app synced to the tracking device and the handheld GPS device often did not match up. For these reasons, it was often difficult to pin-point the exact location of the tree in question. Professor Hupy advised that a 10 meter buffer from the exact point location would suffice for the purposes of the exercise.

The excursion forced students to get lost and rely on their mapping and location skills to return back to the original meeting point. Overall, the exercise was a stimulating challenge that allowed students to do some hiking and exploring in the backyards of Eau Claire.

Community Garden Sampling and Drone Work

Introduction:

This assignment aimed to collect surveyed data of a community garden located in Eau Claire, Wisconsin while simultaneously introducing students to a variety of new data collection tools. Tools utilized for collecting data included a survey grade GPS, thermometer, pH reader, and a TDR Probe for measuring volumetric water content within soils. Later, an additional drone survey of the landscape would contribute to the overall collected data. 

 Methods:

For the purposes of this lab, the class met at the garden location on April 26th and collaborated as a single, large scale group to collect the various types of data necessary within the community garden. Sub-groups of students within the class were created so that each group was responsible for a single data collection tool. Groups were encouraged to switch tools with other groups throughout so that each sub-team could become familiar with all of the data collection methods being utilized. 

The first data collection tool utilized in the community garden survey was a Dual Frequency Survey Grade GPS shown in Figure 1 below for assessing the very specific locations where data was being collected. Each of the points were marked by orange flags. The device surveyed a total of 30 data location points for the first 10 data points collected, but was shortened to 10 data points per stop after survey point 10 to speed up the collection process.

Figure 1: Using the Dual Frequency Survey Grade GPS Unit

Figure 2: pH Measuring Tool

The next tool was a pH probe that worked to measure the acidity levels found within the soil points surveyed.  A sample of soil from each of the data points was scooped into a container and diluted with water so that the probe could be inserted into the container to measure the pH levels found in the soils in that area. Figure 2 provides an image of the tool while Figures 3 and 4 show a peer collecting the necessary data. 

Figure 3: Reading Soil Content pH levels

Figure 4: Diluting the Soil with Water

Figure 5: TDR Probe Measuring Water Content in Soils

The third tool used for data collection was the Time-Domain Reflectometry (TDR) Probe, which sent out electrical pulses into the soil structure to measure each collection point's volumetric water content as a percentage. A picture of this tool is provided in Figure 5. 

The last group used a standard thermometer to measure the temperature of the soil at each of the marked survey points. Given the common use of the tool, a photo is not provided. 

A combination of the resulting data collected was entered in to the survey grade GPS at each of the surveyed points, storing the field data into its attribute table. Once all points were collected with measurements using each of these tools, the data is ready to be viewed and manipulated in ArcGIS. Since the project was a class collaboration, Professor Hupy offered to combine the data into a single spreadsheet for use by the rest of the class. 

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Figure 6: Ground Control Point

On day two of the project, students prepared the area for a flyover mission using a M600 UAS drone. Student's laid out the route of the drones mission by setting up ground control points (GCP) and collecting their x,y location data for input into the drone's course. A sample ground control point is pictured in Figure 6, and the collection of its specific location data using same survey grade GPS unit as was used in part one of the lab can be seen collecting its location point in Figure 7 below.

Figure 7: Survey Grade GPS marking the location of the GCP

With the GCP's laid out and mapped, the drone was ready for its flyover mission, taking pictures and collecting data of the surveyed area. Figures 8 and 9 show pictures of the M600 UAS drone used in flight, price tagged at $13,000. Once the flyover run is complete, to location points collected at each of the GCPs will be used when imported into ArcGIS to tie down the photos taken by the drone into a cohesive mosaic of the surveyed area.

Figure 8: M600 Drone 

Figure 9: Professor Hupy seen Troubleshooting

Finally, using the outputs of the data collected by the tools detailed in part one of the assignment in combination with the resulting final mosaic of the landscape surveyed in part two, a variety of maps can be made to symbolize the significance in the collected data.

Results:

The first of a total of five maps generated from the collected data was a locator map of the Community Garden Project within Eau Claire (Figure 10). Points where the data was collected within the garden are marked in yellow, paired with a base map at the bottom most layer, overlaid by the resulting mosaic generated in the flyover run to provide an updated image of what the site looked like at the time of data collection. While there may be a few feet in error to account for between the mosaic and the underlain base map, the two files appear to align fairly well.

Figure 10: Locator map of the community garden project location

Next, a series of four interpolation maps could be generated to showcase the distribution of the data collected at the various point locations. The first data symbolized was the elevation of the sites location, as shown in the map in Figure 11. The elevation of the sight was relatively flat, ranging only by about 1 meter in elevation between any two given points. The patterns in elevation tended to decrease slightly to the East, which could suggest that the watershed patterns would end up trailing to the East as well.

Figure 11: Site Elevation Interpolation Map

The next set of collected data accounted for the ground temperature of the analyzed soils. The map in Figure 12 shows cooler temperatures recorded at the western side of the garden and slightly warmer temperatures on the eastern half. Temperatures ranged between 11.6 and 13.1 degrees Celcius, fluxuating only by 1.5 degrees overall.

Figure 12: Interpolation map of ground temperatures at site location

Next, moisture content data was interpolated for analysis, resulting in the map in Figure 13. As predicted by the elevation map, the percentage of water content is lower to the northwest, and higher to the southeast, most likely following the areas larger scale drainage basin. Moisture content in the soil tended to have the widest values range of all the explored variables, ranging up to a 13% difference between collected point data!

Figure 13: Map of soils moisture content in site area.

Finally, the last map in Figure 14 accounted for the pH Levels read by the probes in the soil content. In this map, water appears more acidic in the northwest, and more basic in the southeast. This could have implications on plant growth in these areas, as optimal pH levels for plant growth average at a pH level of 6.5. The higher levels accounted for in the southeast portion of the garden could threaten the plants attempting to grow in this area.

Figure 14: pH Levels of Soil Content in Site Location

Conclusion:

This project worked to introduce students to a variety of new tools that can be used for data collection while out in the field. Upon conclusion of this project, students gained experience working with the following field data collection tools: survey grade GPS, thermometer, pH reader, and a TDR Probe. It exposed students to the benefits of drone use in the field and how data can later be compiled to reflect various details in a given area.