Exercise 10: Using Survey Grade GPS and other Survey Equipment

Introduction

This exercise provided the opportunity to conduct a survey using a variety of survey equipment. Some of the equipment used included: survey-grade GPS receiver, TDR probe to measure moisture in the soil, soil thermometers, and soil pH monitors. The opportunity to see a drone fly by using a grid mission was part of the exercise to collect imagery of the study area.

Study Area
The study area is located within the City of Eau Claire (Figure 1). The study area is next to South Middle School. It is a garden that is next to a couple retention ponds.

Figure 1. Study Area located at 44°46'42.6"N 91°28'22.8"W.

Methods
By using different equipment, steps were taken to survey the garden that was located in the study area. Points that were surveyed were first identified by using an orange flag. The flags were placed around the garden in a grid formation. The different tools were then used to test the soil where the flags were placed. The pH and temperature of the soil were first tested using the soil thermometer and soil pH monitors (Figure 2).

Figure 2. An example of one of the tools used to survey, pH monitor. 

Next the Time-Domain Reflectometry (TDR) probe was used to measure the moisture in the ground (Figure 3). Various points were taken around the flag and then averaged to get the average soil moisture content around the point.

Figure 3. Example of the TDR probe used to test the soil moisture.

The survey-grade GPS station is located directly on top of the designated point (Figure 4). It marks the location of the point in an accurate manner by averaging the 30 locations that were taken. The data collected for the pH, soil temperature, and soil moisture can be added to the receiver to keep the data all together with the specific location. In case of error, the data was still all collected manually in a notebook.

Figure 4. Survey-grade GPS station in the process of gathering and inputting location data and other attributes.

To capture the aerial image, the DJI M600 unmanned aerial platform was flown over the study area (Figure 5). The imagery that was used was collected from the DJI Phantom 3 Advanced and the images were processed in Pix4D Mapper. Ground control points were used to connect the overlapping images together. This creates a high resolution image of wehre the points were collected with the GPS receiver.

Figure 5. Aerial View of the Garden at 70 meters using the DJI Phantom 3 Advanced.

Results

Figure 6. Map of the variation in soil moisture. 

The soil moisture varies throughout the garden, with the middle areas of the garden consisting of a higher moisture content (Figure 6). The moisture content was also higher because it had just previously rained before the survey was done.

Figure 7. pH level of the soil based on acidity. 

 The acidity of the soil was higher in the lower right area of the garden (Figure 7). This created a great change across the plain of the community garden. Certain factors of that one plot could cause a change in the pH, such as the techniques used to garden.

Figure 8. Soil temperature measured in Degrees Celsius.

The temperature of the soil in the community garden was for the most part consistent. The temperatures on the right side (lower right specifically) shows variation in having lower temperatures (Figure 8).


Conclusion
After having the opportunity to use various survey equipment, there is many effective ways to collect data. By having many different surveying techniques, it makes it more beneficial in data collection to fully understand nature of the study area. By using multiple attributes, many different conclusion can be made about the study area.