Field Activity 6: Conducting a Distance Azimuth Survey

Introduction

The point of Field Activity 5 is to create a field survey using azimuth angles and distance between oneself and the object being surveyed. This is extremely important when one has no other form of survey techniques available, such as a survey GPS. The field activity's main purpose is to collect a tree survey of Putnam Park in UW -Eau Claire. It is done without a survey GPS, and completed with just basic technologies. Data normalization is incredibly important when working with different groups of surveyors, so the process for creating fields in Field Activity is as follows: x, y, distance, azimuth, diameter at breast height (DBH), tree type, and the point number. This facilitates the correct data entry among different groups of people at different locations. The "X" field is longitude, the "Y" field is latitude, the azimuth is the angle to the tree being surveyed form the surveyor, distance is the distance in meters to the tree, DBH is diameter in cm, tree type identifies the type of tree, and the point number is the different locations a survey is collected.

Figure 1: Black box indicates study area of tree survey

The first point of study by the Geog. 336 class is important because it provides a base point for the rest of the study. The other two points should be collected, and reviewed to make sure that the latitude and longitude make sense spatially.

Methods

Materials

• Hand Held GPS locator
• Rangefinder
• Tree Diameter Tape
• Compass
• Field Notebook

Figure 2: Collecting the azimuth (right) and the distance (left).

The first step is to work as a class to collect the first set of ten trees at Point 1, where the class starts. The GPS point is collected and used to enter all of the data for the ten trees being collected. Someone then uses the compass to find the azimuth angle to a certain tree. Once that is completed, someone uses the rangefinder to shoot the distance to the tree being surveyed to collect the distance in meters (Figure 2). Another person then uses the diameter tape to collect the diameter at breast height, which is important because the tree could have abnormalities lower down, so breast height is a good normalization technique (Figure 3). Once this is done, the tree is identified and logged in the data notebook. The notebook is important because in an azimuth distance survey, there is a good chance that there will be no technology connection to satellites to log the data. The point number is also logged for each tree as 1. Once this is done, different groups go to two other points away from the base point to collect more data for ten trees at each point. 

Figure 3: Collecting the DBH.

The next step is to enter all of the data into an Excel spreadsheet in the appropriate fields. This is then imported into ArcMap by creating a geodatabase for the survey. Once this is done, right click on the GDB and select import Table(single). Select the table to import and enter in the appropriate fields. The next step is to use Bearing Distance to Line command in Data Management->Features. This is used to input the table into lines from each point. The feature class is then input into the Feature Vertices to Points command within the same folder of geoprocesses. This creates the points of each tree. Once these feature classes are added to a blank map, a base map is added.

Results/ Discussion

Figure 4: Final Survey Map 

The data is created to show the different trees that are surveyed (Figure 4). The points all show the correct distances and azimuths to each tree. There are, however, difficulties that happen in this survey. The points are collected beneath a ridge by the UW -Eau Claire campus, so all of the GPS points are off in the initial table. 

Figure 5: Initial map created from data.

The intial points are all off, so the identifier tool has to be used to collect the right lat and long of the actual points. The table is edited to reflect this create the final map (Figure 4). The hand written data works exceptionally well with the other technologies at hand. Although the data was wrong at first in the x and y field, this did not create too much of a problem for creating the final map. This method is effective if no other option is available.

Conclusion

This was a very effective distance azimuth survey. Although some of the data was wrong initially, identifying the correct lat and long is not a big issue. It is different from a survey that would be completed with a survey GPS, as all of the measurement is done by hand, including the distance and azimuth of each tree from each point. For simple surveys such as tree collection, the distance azimuth survey is effective.