The purpose of this lab was two part. Part one was to practice using dual frequency survey grade GPS to collect data in the field. The survey grade GPS was used to collect attributes on a community garden in a neighborhood in Eau Claire, WI. The soil pH, soil temperature, and soil moisture were measured at 28 dispersed points within the garden. Part two was to use the Survey GPS to gather GCP marks and use an unmanned aerial system (UAS) to collect imagery to use in visualizing the results from part one data collection.
Study Area
The study area for this lab was a community garden called the South Side Gardens. Figure 1 shows the location of the garden. The plots within the garden are 10' by 20' or 20' by 20'. The garden is enclosed with a 9 foot deer fence, which can be seen in Figure 2. Evenly spaced samples were taken down the rows of plots.
Figure 1. The study area of the South Side
community garden.
Figure 2. A picture taken at the South Side
Gardens of the garden plots.
Methods
Part 1:
Four key pieces of equipment were used to complete this lab:
- TDR Probe
- pH Probe
- Temperature Probe
- Topcon Survey Grade GPS
First, 28 orange flags were placed around the garden study area marking the locations that samples will be taken.
TDR Probe
A Time Domain Reflectometry (TDR) Probe was used to measure the volumetric water content of the soil as a percentage. The probe had two long metal prongs that stuck out of a purple box with a screen and two handles. The probe worked by sticking the two prongs into the soil and pressing the READ button on the purple box. The probe works by measuring the travel time of waves along the probe in the soil to give the moisture measurement. The screen rendered two numbers, the HiClay vWC% measured number of the top number on the screen was recorded after taking a few measurements around the sample point and averaging the values. Figure 3 shows the probe in use and Figure 4 shows what the screen on the device looks like after taking a measurement.
Figure 3. Classmate Kayla using the TDR probe by sticking the prongs into the ground of the sampling location.
Figure 4. The appearance of the TDR probe with the prongs sticking into the ground. The top number on the screen is the value that was recorded.
pH Probe
A pH probe was used to measure the pH level of a soil sample at each sample point in the garden. The probe was calibrated by using special solutions. The probe was always rinsed with distilled water before a measurement was taken. A sample of soil was taken in the cap of the probe and mixed with distilled water to form a solution. Next the tip of the probe was inserted into the solution resulting in a pH measurement of how acidic or basic the soil being sampled was. Figure 5 shows the pH probe being used to measure the pH of a soil sample.
Figure 5. Classmate Alex using the
pH probe to get a pH measurement
of how acidic or basic the soil
sample was.
Temperature Probe
Figure 6. Temperature probe is inserted into the ground to
get the soil temperature.
Topcon Survey Grade GPS
A Topcon Survey Grade GPS unit was used to gather the coordinate location of the sample point. The unit was able to get the coordinate location within centimeters of the exact location. The unit was placed directly over the flagged location where samples were taken. After the coordinate location of the sample point was recorded. All of the other attributes, soil moisture, pH, and temperature were manually entered in the electronic unit at each point as well.
The TDR soil moisture measurement, temperature, and pH measurements were all recorded on paper in a notebook as a hard copy and inputted into the Topcon survey grade GPS equipment for each location samples were taken. Hard copies should always be taken in case of a technological error or malfunction.
Following the lab the flags marking sample locations were collected. The data recorded in the Topcon Survey Grade GPS unit was downloaded and normalized for use in ArcMap.
Part 2:
In part two a Matrice 600 (M600) platform was used to collect aerial imagery of the study area. An image of the M600 can be seen in Figure 8.
Figure 11. Professor Hupy demonstrating how properly center the Topcon Survey Grade GPS unit over a ground control point.
Figure 12. The bubble on the Topcon Survey Grade GPS unit that needed to appear within the black circle to insure that the unit was level and accurate coordinate locations would be recorded.
After all GPS were in place with coordinate locations recorded, flight checks on the M600 were conducted. Software updates were required and a few other glitches needed to be resolved before the M600 could fly, like remembering to place the SD card in the apparatus. Once all of the proper adjustments were made the M600 flew a predetermined flight path. The M600 taking off for flight can be seen in Figure 13. In Figure 14 the max altitude the flight was flown at. The M600 can reach very high altitudes. A video of the M600 landing after its flight can be seen in Figure 15.
Results
The results from the unmanned aerial system (UAS) flight done by the M600 platform turned out rally well. Some of the imagery collected by the M600 can be seen in Figure 16. The garden that was the area of study can be seen just below the line of trees in the center of the imagery.
Once imported into ArcMap the soil data collection points were visible in their correct coordinate location recorded by the Topcon Survey Grade GPS unit. The locations of where the soil attribute data was collected within the community garden can be seen in Figure 17.
Figure 18, shows how the elevation changes through the sampled area in the community garden. Moving west to east through the garden the elevation increased. The highest elevations are located on the east side of the garden and the lowest elevations are located on the west side of the garden. One could expect that during a heavy rainfall the plots on the west side of the garden located in the lower elevations would receive much of the runoff water and become over saturated.
Figure 19, shows the distribution of soil pH through the sampled area of the community garden. A general observation is that the more acidic pH locations are on the outer edges of the sampled area with a higher concentration located on the west side of the garden. The more basic pH levels are located in the center of the study area in the center of the community garden.
Figure 21, shows the distribution of soil moisture content through the sampled area of the community garden. The soil moisture content was higher on the east side of the garden than the west side of the garden. This is unusual because the west side of the garden is at a lower elevation than the west, so any runoff water from any precipitation would be moving toward the west side. The soils on the east side of the garden must have more porosity and hold water more tightly than the soils on the west side of the garden.
Conclusions
A significant amount of data was collected in this lab. It is important to always have hard copies of the data in case an error with the electronic data occurs. The sector of geospatial techniques that works with using UAS platforms is a growing sector with many applications. Learning the basics behind this technology and the possibility of the applications is very valuable.
Sources
A method of measuring soil moisture by time-domain reflectometry. (n.d.). Retrieved May 01, 2017, from http://www.sciencedirect.com/science/article/pii/0022169486900971.
Eau Claire Community Gardens. (2016). retrieved May 01, 2017, from http://www.eauclairecommunuitygardens.com/southside/southside.htm.
Figure 7. The Topcon Survey Grade GPS unit used to record the
coordinates of the sample point and record all of the attribute
data of the samples taken at the location.
The TDR soil moisture measurement, temperature, and pH measurements were all recorded on paper in a notebook as a hard copy and inputted into the Topcon survey grade GPS equipment for each location samples were taken. Hard copies should always be taken in case of a technological error or malfunction.
Following the lab the flags marking sample locations were collected. The data recorded in the Topcon Survey Grade GPS unit was downloaded and normalized for use in ArcMap.
Part 2:
In part two a Matrice 600 (M600) platform was used to collect aerial imagery of the study area. An image of the M600 can be seen in Figure 8.
Figure 8. Matrice 600 platform used to collect aerial imagery of the garden study area.
Two other components were used to fly the M600. A RTK was used to give accuracy to the flight. The RTK can be seen in Figure 9. A controller was also needed to be able to control the M600 while in flight. An iPad was attached to the controller with a preset flight path that the M600 followed during its flight. The controller and iPad can be seen in Figure 10.
Figure 9. RTK used to improve the Figure 10. Controller and iPad used to
accuracy of the flight. control the M600 while in flight.
Before the M600 could be flown a total of nine ground control points (GCPs) needed to be laid out in the garden. At each location where a GCP was placed the Topcon Survey Grade GPS unit was used to record the exact coordinate location of the GCP. This was done by placing the Topcon Survey Grade GPS unit was placed directly over the center of the pink and black GCP. The unit being properly placed over a GCP can be seen in Figure 11. When placing the survey grade GPS unit it was important to make sure the center spoke was dead center over the GCP and the unit was level by making sure the bubble on the unit was placed center to a circle guaranteeing the unit was level. The bubble that needed to be perfectly positioned can be seen in Figure 12.
Figure 11. Professor Hupy demonstrating how properly center the Topcon Survey Grade GPS unit over a ground control point.
Figure 12. The bubble on the Topcon Survey Grade GPS unit that needed to appear within the black circle to insure that the unit was level and accurate coordinate locations would be recorded.
After all GPS were in place with coordinate locations recorded, flight checks on the M600 were conducted. Software updates were required and a few other glitches needed to be resolved before the M600 could fly, like remembering to place the SD card in the apparatus. Once all of the proper adjustments were made the M600 flew a predetermined flight path. The M600 taking off for flight can be seen in Figure 13. In Figure 14 the max altitude the flight was flown at. The M600 can reach very high altitudes. A video of the M600 landing after its flight can be seen in Figure 15.
Figure 13. The M600 taking off from the Figure 14. The M600 at the max
ground to fly its flight path. preset altitude for this flight path.
Figure 15.The M600 landing after completing its flight path.
The flight imagery was processed in Pix4D software following the M600 flight. Both the Pix4D extracted imagery and the data coordinate points and attribute data collected in part one were imported into ArcMap for data interpretation and map creation. The natural neighbor interpolation was performed on four attributes, elevation, soil pH, soil moisture, and soil temperature, for data interpretation.
Results
The results from the unmanned aerial system (UAS) flight done by the M600 platform turned out rally well. Some of the imagery collected by the M600 can be seen in Figure 16. The garden that was the area of study can be seen just below the line of trees in the center of the imagery.
Figure 16.
Once imported into ArcMap the soil data collection points were visible in their correct coordinate location recorded by the Topcon Survey Grade GPS unit. The locations of where the soil attribute data was collected within the community garden can be seen in Figure 17.
Figure 17. The points were soil attribute data was collected within the community garden.
Figure 18. Elevation of the community garden. Elevation increases west to east
across the garden plots.
Figure 19, shows the distribution of soil pH through the sampled area of the community garden. A general observation is that the more acidic pH locations are on the outer edges of the sampled area with a higher concentration located on the west side of the garden. The more basic pH levels are located in the center of the study area in the center of the community garden.
Figure 19. Soil pH in the community garden. Soil pH is generally more acidic on
the outer edges and the west side of the community garden, while
the center of the sampled area has a more basic pH.
Figure 20, shows the distribution of soil temperature through the sampled area of the community garden. The soil temperature was higher on the east side of the garden than the west side.
Figure 20. Soil temperature in the community garden. Soil temperature was lower
on the west side of the garden and higher on the east side of the garden.
Figure 21, shows the distribution of soil moisture content through the sampled area of the community garden. The soil moisture content was higher on the east side of the garden than the west side of the garden. This is unusual because the west side of the garden is at a lower elevation than the west, so any runoff water from any precipitation would be moving toward the west side. The soils on the east side of the garden must have more porosity and hold water more tightly than the soils on the west side of the garden.
Figure 21. Soil moisture content in the community garden. The soil moisture
was generally higher on the east side of the garden.
Overall the best place to have a garden plot in this community garden depends on what type of crop is being grown. If a crop requires more water it should be grown on the east side of the garden unless the crop is being grown during a rainy season which due to elevation and water runoff, the west die of the garden would be expected to have a higher moisture content. Plants generally speaking grow best in soils of pH between six and seven. A plot located more on the edges or more on the west side of the garden would provide the best pH levels. If the crop being grown requires warmer temperatures plots on the east side of the garden would provide warmer temperatures. Overall, the east side of the garden provides the most ideal locations for plant growth.
Conclusions
A significant amount of data was collected in this lab. It is important to always have hard copies of the data in case an error with the electronic data occurs. The sector of geospatial techniques that works with using UAS platforms is a growing sector with many applications. Learning the basics behind this technology and the possibility of the applications is very valuable.
Sources
A method of measuring soil moisture by time-domain reflectometry. (n.d.). Retrieved May 01, 2017, from http://www.sciencedirect.com/science/article/pii/0022169486900971.
Eau Claire Community Gardens. (2016). retrieved May 01, 2017, from http://www.eauclairecommunuitygardens.com/southside/southside.htm.
