Learning Module: Field Methods when a GPS just won't do!

Introduction

GPS handhelds are great when they work. However, they need a clear view of a large area of the sky to get a "fix". Here at HSU, and in many areas around the world, this is hard to come by either because you are in a canyon, have a lot of tree cover, or you need higher resolution than a typical GPS allows. You could purchase and carry in a sub-meter GPS but there are times when you cannot afford one or one is simply not available. In these cases, we need to fall back on other methods to get high resolution data.

Learning Outcomes

By the end of this module, you should be able to:

• Establish a bench mark to make other measures from
• Use a compass and range finder to find horizontal distance and direction
• Correct directions for declination
• Compute eastings and northings from a benchmark, distances, and corrected directions
• Estimate uncertainty of coordinates from distance and direction measurements

Activities

Go to the Arcata city website and download the map for the Arcata Forest. Take a look at the map and ask your self:

• Who is the audience for the map?
• What is the map's projection and datum?
• What information does the map provide?
• How accurate is the information?
• How accurate does it have to be?
• Does it meet the needs of researchers or foresters working in the forest?

Try finding a location from a distance and direction:

• Given: 40.8735, -124.0782
• Direction: 30 degrees
• Distance: 1000 meters
• Where does this put you?

Hints: Use the web to convert direction in degrees to radians Use the web to convert DD to UTM Use a mapping app to find the location

Presentations

Field Methods 2

If needed: Spatial Reference Issues

Lab

Computing coordinates with a compass and range finder.

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