Field Activity 1: Creation of a Digital Elevation Surface

Introduction

Geospatial Field Methods is a course taught at University of Wisconsin Eau-Claire by Joe Hupy.  This course is designed to help students become familiar with using geographic field techniques outside of the classroom as a 'hands on' learning style.  A key goal of the course is to have students critically think about concepts and use our skills to fix problems or answer questions.  This first assignment was a field activity that had the class, split into groups, create digital elevation surfaces.  then to measure these box by creating our own grid system that contained a X, Y, and Z measurements.  These surfaces were created outside in sand boxes, we designed the changes in elevation with snow by digging and building up the snow.

Methods

The first task of the project was to build the structure so our group could take measurements.  The plan was to flatten the top of the surface and dig down from there.  This was down to set up our grid system and to make the measurements much easier.  We then proceeded to dig down using our hands and shovels trying to include a ridge, hill, depression, valley, and plain.  After the digging was completed the grid system was set up, measuring the side of the sand box every three inches and marking it with a pin.  Then ropes were pinned down tightly and stretching across the sand box, making rows and columns. You can see this grid system, using ropes and pins in the picture below.

The snow was sprayed with water
so the snow would freeze
creating accurate measurements. 

Image of our grid system.  It took a long time setting up
each rope along with the temperature being zero degrees. 

The next step was to take measurements, the long side of the sand box was given Y coordinates and the short side was given X coordinates.  Also with this measurement calling for elevation to be displayed, a Z coordinate must used to read the height of the surface.  The measurements were taken in centimeters and were done in an ordered fashion, X1, Y1, and Z would equal the height of the surface.  Our group used a measuring stick to take measurements and the stick was placed in the upper right corner of each square to take consistent measurements.  The measurements were immediately placed into an excel spread sheet as one of my group members had his lab top outside to type in the numbers.

My group taking measurements, one reading off the
height of the surface, and the other typing it into his
lab top 

This is a portion of our groups excel
spreadsheet.  Containing X, Y, Z, and
the number of points. 

A total of 420 measurement points were taken, giving our team a very accurate reading of the elevation surfaces.  It was decided by our team that we will take close measurements of each area of the sand box because the terrain was very different.  

Discussion/Conclusion

Creating our digital elation surface was very fun and challenging.  It made the group and I critically think about the best way to shape our sandbox and take measurements.  Making the measurements all below zero was a great idea to make the process go along much smoother.  I would predict the results that come in the next week will be the most accurate of all the groups compared to their real life structure.  Our grid system using the strings to carefully measure each X, Y, and Z coordinate was very accurate and zero guessing was need when taking the measurements.  Creating the images on ArcGIS should look very similar to the original structure created.